Machining Level I Past Paper PDF, August 2022

Machining Level I Based On March 2022, Curriculum Version 1 Module Title: -Test and Identify Properties OfMetals Module Code: - IND MAC1 M 02 0322 Nominal Duration: 29 Hour Prepared By: Ministry Of Labour and Skill...

Machining Level I Based On March 2022, Curriculum Version 1 Module Title: -Test and Identify Properties OfMetals Module Code: - IND MAC1 M 02 0322 Nominal Duration: 29 Hour Prepared By: Ministry Of Labour and Skill August, 2022 Addis Ababa, Ethiopia Table Of Content Introduction to the Module ____________________________________________________ 4 Unit one: Classify common ferrous and non-ferrous metals _______________________ 6 1.1. Classification of Ferrous, Non-Ferrous and Alloys Metals ___________________ 7 1.1.1. Introduction to Metals: _____________________________________________ 7 1.1.2. Ferrous metals ____________________________________________________ 7 1.1.3. Non-ferrous metals _______________________________________________ 10 1.1.4. Alloys _________________________________________________________ 15 1.2. Properties of metal and metal alloys ____________________________________ 21 1.3. Metal Identification Methods _________________________________________ 29 self Check Unit ________________________________________________________ 32 Unit Two: Test Basic Applications and Methods for Manufacturing ______________ 34 2.1. Introduction _______________________________________________________ 35 2.1.1. Selecting Cutting Tools forthe Machinability___________________________ 35 2.1.2. Metallurgy of Machining __________________________________________ 35 2.1.4. Grains and Strains Boundaries ______________________________________ 39 2.2. Testing For Manufacturing ___________________________________________ 40 2.3. Manufacturing methods of processing engineering materials ________________ 41 2.4. ExperiencingMethodsofManufacturing _________________________________ 44 Self-Check –Unit- II ______________________________________________________ 45 Unit Three: Perform Basic Common Metal Tests ______________________________ 47 3.1. Introduction _______________________________________________________ 48 3.1.1. Tensile test _____________________________________________________ 48 3.1.2. Compression Test ________________________________________________ 51 3.1.3. Hardness test ____________________________________________________ 51 3.1.4. Impact test ______________________________________________________ 55 3.1.5. Creep Test ______________________________________________________ 56 3.1.6. Torsion Test ____________________________________________________ 57 3.1.7. Bending Test:- ___________________________________________________ 57 3.1.8. Shear Test:- _____________________________________________________ 57 3.1.9. Spark Test ______________________________________________________ 58 3.2. Nondestructive Testing Methods ______________________________________ 59 3.2.1. Magnetic Particle Testing __________________________________________ 60 3.2.2. Liquid penetrates _________________________________________________ 60 3.2.3. Eddy - Current Testing ____________________________________________ 61 3.2.4. Ultrasonic Testing ________________________________________________ 61 3.2.5. X-ray methods of Radiography ______________________________________ 62 3.3. Record and report test results of materials _______________________________ 62 Self-Check –Unit- III _____________________________________________________ 64  Operation Sheet 1 ________________________________________________________ 65 Operation Sheet 2 ________________________________________________________ 65 Page 1 of 93 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright Lab Test 1 ______________________________________________________________ 67 Lab test-2 ______________________________________________________________ 68 Unit Four: Define common heat treatment outcomes and applications _____________ 69 4.1. Introduction _______________________________________________________ 70 4.2. Steps of Heat Treatment ___________________________________________ 72 4.3. Classification of Heat Treatment Processes ______________________________ 73 4.3.1. Annealing ______________________________________________________ 74 4.3.2. Normalizing ____________________________________________________ 75 4.3.3. Hardening ______________________________________________________ 75 4.3.4. Tempering ______________________________________________________ 76 4.3.5. Case (Surface) Hardening __________________________________________ 76 4.4. Quenching Media __________________________________________________ 80 4.5. Heat Treatment of Non-Ferrous Metals? ________________________________ 80 Self-Check –Unit- IV _____________________________________________________ 82 Operation sheet:-1 (heat treatment process) ____________________________________ 84 (Lap)Test-1 _____________________________________________________________ 87 Page 2 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright Acknowledgment Ministry of Labor and Skills wish to extend thanks and appreciation to the many representatives of TVET instructors and respective industry experts who donated their time and expertise to the development of this Teaching, Training and Learning Materials (TTLM). Acronym AIST-American Iron and Steel Institute Au-Gold Ag-Silver C-Carbon Cr-Chromium Cu-Copper DT-Destructive Testing F-Force Fe-Iron Hv-Vickers Hardness Mg-Magnesium Maps-Mega Pascal Mn-Manganese Page 4 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright NDT-Non-Destructive Testing Ni-Nickel P-Phosphorus Pb-Lead Pt-Platinum OHS-Occupational Health and Safety S-Sulfur SAE-Society of Automotive Engineering Si-Silicon Introduction to the Module In machining filed; the Testing and Identifying Properties of Metals project helps to know the classification common ferrous and non-ferrous metals; to management of OHS in the workplace; to Test basic applications and methods for manufacturing; to perform basic common metal tests ;to define common heat treatment outcomes and applications; Assess quality of test and complete documentation. This module is designed to meet the industry requirement under the machining occupational standard, particularly for the unit of competency: Testing and Identifying Properties of Metals. This module covers the units: ferrous , non-ferrous and alloy metals Test methods for manufacturing Page 5 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright  metal tests heat treatment Learning Objective of the Module Classify ferrous and non-ferrous metals To know applications and methods for manufacturing of metal property Perform Test a metal property and type Define common heat treatment outcomes and applications Module Instruction For effective use this modules trainees are expected to follow the following module instruction: 1. Read the information written in each unit 2. Accomplish the Self-checks at the end of each unit 3. Perform Operation Sheets which were provided at the end of units 4. Do the “LAP test” giver at the end of each unit and 5. Read the identified reference book for Examples and exercise Unit one: Classify common ferrous and non-ferrous metals This unit is developed to provide you the necessary information regarding the following content coverage and topics: Classification of metals metal properties This unit will also assist you to attain the learning outcomes stated in the cover page. Specifically, upon completion of this learning guide, you will be able to: Identify types of metal and their application. Identify property of metal. Page 6 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright 1.1. Classification of Ferrous, Non-Ferrous and Alloys Metals 1.1.1. Introduction to Metals: Because of the widespread use and necessity for metals in agriculture, building, automotive, airplane and different usage it is important for the worker to have a basic understanding of metals and metallurgy when fabricating and making repairs on metals. Steelworkers need to know the two basic types of metal and be able to provide initial identification. While they primarily work with the ferrous metals of iron and steel, they also need to be able to identify and become familiar with the nonferrous metals coming into more use each day. Metal-Metal is an element. There are over 118 known elements, and about 75 percent of them are classified as metals. Alloy is a mixture of two or more metals or of metals and one or more non-metals The elements added to a metal to form an alloy may be either metal or non-metal. In most cases alloys have more desirable properties and are less expensive than pure metals. Classification of metal These metals can be broken down into four groups and classified as follows: Ferrous Metals Non-ferrous metals Ferrous Alloys Non-ferrous Alloys Page 7 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright 1.1.2. Ferrous metals Metals whose chief ingredient is iron. Pig iron, cast iron, wrought iron, and steel are examples of ferrous metals. Pig iron or cured iron. It is iron ore changed to pig iron by a blast furnace. Cast iron:-It is a product of pig iron and contains a considerable amount of carbon and some impurities. It is brittle and granular in structure. It is formed by pouring into special castings. The basic principal raw material for all ferrous metals is pig iron which is obtained by melting iron ore, coke and limestone, in the blast furnace. I. Pig Iron Pig iron was originated in the early days by reduction or iron ores in blast furnace and when the total output of the blast furnace was sand cast into pigs which is a mass of iron roughly resembling a reclining pig. It is produced in a blast furnace and is the first product in the process of converting iron ore into useful ferrous metal. The iron ore becomes pig iron when the impurities are burnt out in a blast furnace. The charge in the blast furnace for manufacturing pig iron is (a) Ore - Consisting of iron oxide or carbonate associated with earth impurities. (b) Coke - A fuel (c) Limestone - A flux In addition to iron, pig iron contains various other constituents in varying form of impurity such carbon, silicon, sulphur, manganese and phosphorus etc. It has the following approximate composition which is as given as under. Carbon — 4 to 4.5% Phosphorus — 0.1 to 2.0% Silicon — 0.4 to 2.0% Sulphur — 0.4 to 1.0% Manganese — 0.2 to 1.5 % Iron — Remaining % Pig iron is the raw material for all iron and steel products. It is of great importance in the foundry and in steel making process. Page 8 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright  Carbon exists in iron in free form (graphite) and/or in combined form (cementite and pearlite). Pig iron is classified on the basis of contents of free and combined carbon as follows. These classifications are also termed as grades. i. Grey pig iron (Grades 1, 2 and 3) Grey pig iron contains about 3% carbon in free form (i.e., graphite form) and about 1% carbon in combined form. This is a soft type of pig iron. ii. White pig iron (Grades 4) White pig iron is hard and strong. It contains almost all of the carbon in the combined form. iii. Mottled pig iron (Grade 5) This type of pig iron is in between the grey and white variety. It has an average hardness and molted appearance. The free and combined forms of carbon are in almost equal proportion in mottled pig iron. II. Cast iron Cast iron is basically an alloy of iron and carbon and is obtained by re-melting pig iron with coke, limestone and steel scrap in a furnace known as cupola. The carbon content in cast iron varies from 1.7% to 6.67%. It also contains small amounts of silicon, manganese, phosphorus and sulphur in form of impurities elements. General properties of cast iron  Cast irons are difficult to weld.  Cast iron is very brittle and weak in tension and therefore it cannot be used for making bolts and machine parts which are liable to tension.  It has low cost, good casting characteristics, high compressive strength, high wear resistance and excellent machinability.  Its tensile strength varies from 100 to 200 MPa, compressive strength from 400 to1000 MPa and shear strength is 120 MPa.  The compressive strength of cast iron is much greater than the tensile strength. There are four kinds of cast iron  Grey cast iron  White cast iron  Malleable cast iron, and  Nodular cast iron Page 9 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright  i. Gray cast iron Gray cast iron is grey in color which is due to the carbon being principally in the form of graphite (C in free form in iron). It contains:- C = 2.5 to 3.8%. Mn = 0.4 to 1.0% Si = 1.1 to 2.8 % P = less than 0.15% S = less than 0.1% It is produced in cupola furnace by refining or pig iron. Properties of gray cast iron When fractured it gives gray color. It can be easily cast. It has lowest melting point. It can be easily machined and possesses mach inability better than steel. It possesses lowest melting of ferrous alloys. It has high resistance to wear. It possesses high compressive strength. It has a low tensile strength. It has very low ductility and low impact strength as compared with steel. Applications of gray cast iron The grey iron castings are mainly used for machine tool bodies, automotive cylinder blocks, pipes and pipe fittings and agricultural implements. The other applications involved are Machine tool structures such as bed, frames, column etc. Household appliances etc. Gas or water pipes for underground purposes. Piston rings. Rolling mill and general machinery parts. Blocks and heads for engines. Frames of electric motor. ii. White cast iron It has a white appearance due to the form in which the carbon is present in the iron. White iron is usually cast in metal moulds which permit a rapid cooling rate so that the carbon remains in solution with the iron. White iron is used for such purposes as chilled iron castings of rollers for rolling mills used in the production of steel plate. It is extremely difficult to machine and the main purpose of white cast iron is to produce malleable iron. C = 3.2 to 3.6%. Mg = 0.1 to 0.4% Page 10 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright  Si = 0.4 to 1.1 % P = less than 0.3% S = less than 0.2% Properties White cast iron Its name is due to the fact that its freshly broken surface shows a bright white fracture. It is very hard due to carbon chemically bonded with iron as iron carbide (Fe3C), which is brittle also. It possesses excellent abrasive wear resistance. Since it is extremely hard, therefore it is very difficult to machine. Its solidification range is 2650-2065°F. The white cast iron has a high tensile strength and a low compressive strength. Applications White cast iron For producing malleable iron castings. For manufacturing those component or parts which require a hard, and abrasion resistant surface such as rim of car. Railway brake blocks. Grey cast iron & white cast iron are:- Low in cost They are very brittle, however They cannot hammer or formed. iii. Malleable iron Malleable iron is produced by placing white iron castings in an annealing furnace and subjecting them to temperatures above 870°. The ordinary cast iron is very hard and brittle. Malleable cast iron is unsuitable for articles which are thin, light and subjected to shock. It can be flattened under pressure by forging and rolling Typical uses for malleable iron are for pipe fittings & plumbing fixtures. Properties Malleable cast iron is like steel than cast iron. It is costly than grey cast iron and cheaper than softer steel. Applications of malleable iron Malleable cast iron are generally used to form automobile parts, agriculture implementation, hinges, door keys, spanners mountings of all sorts, seat wheels, cranks, levers thin, waned components of sewing machines and textiles machine parts. iv. Ductile cast iron (Nodular) Page 11 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright Nodular iron is produced by adding elements such as nickel and molybdenum to the molten metal. Nodular iron is:- Very high strength Good machinability and Good Resistance to wear This type of iron is used for high quality castings such as lathe and machine tool beds and where hard wearing and resistance to shock qualities are required. Silicon is also used as an alloying element since it has no effect on size and distribution of carbon content. The magnesium controls the formation of graphite. But it has little influence on the matrix structure. Nickel and manganese impart strength and ductility. Ductile cast iron has high fluidity, excellent cast ability, strength, high toughness, excellent wear resistance, pressure tightness, weldability and higher machinability in comparison to grey cast iron. v. Wrought iron Wrought iron is mechanical mixture of very pure iron and a silicate slag. It can also be said as a ferrous material, aggregated from a solidifying mass of pasty particles of highly refined metallic iron with which a uniformly distributed quantity of slag is incorporated without subsequent fusion. This iron is produced from pig iron by re-melting it in the puddling furnace. Wrought iron is very ductile; forges well, can easily bend hot or cold, and can be welded. It has a tensile strength of about 275 M Pa and it is high cost. Properties Wrought iron The wrought iron can be easily shaped by hammering, pressing, forging, etc. It is never cast and it can be easily bent when cold. It is tough and it has high ductility and plasticity with which it can be forged and welded easily. It possesses a high resistance towards corrosion. It can accommodate sudden and excessive shocks loads without permanent injury. It has a high resistance towards fatigue. It can be elongated considerably by cold working. It has high electrical conductivity. The melting point of wrought iron is about 1530°C. It has elongation 20% in 200 mm in longitudinal direction and 2–5 % in transverse direction. Applications Wrought iron Page 12 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright It is used for making chains, crane hooks, railway couplings, and water and steam pipes. It has application in the form of plates, sheets, bars, structural works, rivets, and a wide range of tubular products including pipe, tubing and casing, electrical conduit, cold drawn tubing, welding fittings, bridge railings. Page 13 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August, 2022 Author/Copyright  III. Steels Steel is an alloy of iron and carbon with carbon content maximum up to 1.7%. The carbon occurs in the form of iron carbide, because of its ability to increase the hardness and strength of the steel. Plain carbon steels Plain carbon steel is an alloy of iron and carbon. It has good machine ability and malleability. Plain carbon steels are classified by the amount of carbon they contain. i. Low carbon steel, often called mild or soft steel, it contain 0.1 up to 0.3 per cent carbon. Low carbon steels is Have a lower tensile strength and hardness. It is easy welded, machined, and formed. It is used for most bench metal ii. Medium carbon steel It contains 0.3 up to 0.6 percent carbon. Medium carbon steels are used where strength and ductility are required. It is used for many standard machine parts & for projects like hammer heads and clamp parts. iii.High carbon It contains 0.3 up to 0.6 percent carbon. High carbon steels have a higher tensile strength, hardness, and wear resistance but are low in ductility and have poor machinability. It is used for making small tools. 1.1.3. Non-ferrous metals Non- ferrous metals are those which have no iron and are made up of a single element. These are aluminum, copper, lead, magnesium, nickel, tin, tungsten, zinc, silver, and gold. The most common non-ferrous metals and alloys are: aluminum alloys, copper, brass, nickel, and tin, zinc, lead, and magnesium alloys. a) Aluminum It is a white metal produced by electrical process from the oxide (Alumina), which is prepared from a clay mineral called Bauxite. Bauxite is hydrated aluminum oxide. The chief impurities are oxide, silica, clay and titanium oxide. Page 10 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright Properties of Aluminum  Light weight  Good electrical conductivity  Malleability and ductility  High thermal conductivity  Resistance to corrosion  Non-magnetic properties  Most elements alloying aluminum are Cu, Cr, Ni, Mn, Si, and Mg. Uses of Aluminum  It is mainly used in aircraft and automobile parts where saving of weight is an advantage.  It is used for reflectors, mirrors and telescopes.  It is a useful metal for cooking apparatus.  It is a cheap and very important nonferrous metal used for making cooking utensils. b) Copper Copper is one of the most widely used non-ferrous metals in industry. It is extracted from ores of copper such as copper glance, copper pyrites, malachite and azurite. Copper is a corrosion resistant metal of an attractive reddish brown color. Properties of copper  Good resistance to corrosion.  Non-magnetic properties  Pure copper is soft, malleable and ductile metal with a reddish-brown appearance.  High electrical conductibility  It can be soldered, brazed, or welded.  Very good machinability Applications of copper  Copper is mainly used in making electric cables and wires for electric machinery, motor winding, electric conducting appliances, and electroplating etc.  It can be easily forged, casted, rolled and drawn into wires.  Copper in the form of tubes is used widely in heat transfer work mechanical engineering field. Page 11 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright The following copper alloys are important 1) Copper-zinc alloys (Brasses) 2) Copper-tin alloys (Bronzes) c) Brasses Brasses are widely used alloy of copper and zinc. They also contain small amounts of lead or tin or aluminum. The most commonly used copper-zinc alloy is brass. There are various types of brasses, depending upon the proportion of copper and zinc. The fundamental a binary alloy comprises 50% copper and 50% zinc. By adding small quantities of other elements, properties of brass may be greatly changed. For example addition of lead (1 to 2%) improves the machining quality of brass. It has a greater-strength than that of copper, but has a lower thermal and electrical conductivity. Brasses alloys are very resistant to atmospheric corrosion and can be easily soldered. They can be easily fabricated by processes like spinning and can also be electroplated with metals like nickel and chromium. d) Bronzes Bronze is a common alloy of copper and tin. The alloys of copper and tin are generally termed as bronzes. The wide range of composition of these alloys comprise of 75 to 95% copper and 5 to 25% tin. Bronze has higher strength, better corrosion resistance than brasses. It is comparatively hard and resists surface wear and can be shaped or rolled into wire, rods and sheets very easily. It has antifriction or bearing properties. Bronze is costlier than brass. The tensile strength of bronze increases gradually with the amount of tin, reaching a maximum when tin is about 20%. However the percentage of tin content if increases beyond this amount, the tensile strength decreases very rapidly. Bronze is most ductile when it contains about 5% of tin. As the amount of tin increases about 5%, the ductility gradually decreases and practically disappears with about 20% of tin. Whereas presence of zinc in the bronze increases fluidity of molten metal, strength and ductility. e) Nickel Page 12 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright Nickel is a silvery shining white metal having extremely good response to polish. The most important nickel’s ore is iron sulphides which contain about 3% of nickel. About 90% of the total production of nickel is obtained by this source. This ore is mainly found in Canada and Norway. Properties Nickel is as hard as steel. It possesses good heat resistance. It is tough and having good corrosion resistance. Its melting point is 1452°C and specific gravity is 0.85. At normal temperature, nickel is paramagnetic. Nickel alloys are sometimes used for their high potential field strengths, some for their permeability and some for their high coercive force. When it contains small amount of carbon, it is quite malleable. It is somewhat less ductile than soft steel, but small amount of magnesium improves ductility considerably. Applications Nickel is used in kitchen utensils and appliances, and in laundry and dairy machinery. It is extensively useful for electroplating plating work for protecting surfaces of iron and brass from corrosion. It is also utilized as an important alloying element in some type of cast iron and steel. It is helpful for making stainless steel. f) Lead It is a very durable and versatile material. The heavy metal obtained from the bottom of the furnace is further oxidized. Properties Lead has properties of high density and easy workability. It has very good resistance to corrosion and many acids have no chemical action on it. Its melting point is 327°C and specific gravity is 11.35. It is the softest and heaviest of all the common metals. It is very malleable and it can readily be scratched with fingernail when pure. Applications Lead is used in safety plug in boilers, fire door releases and fuses. It is also used in various alloys such as brass and bronze. It finds extensive applications as sheath for electric cables, both overhead and underground. Its sheets are used for making roofs, gutters etc. It is employed for chemical laboratory and plant drains. Page 13 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  In the soldering process, an alloy of lead and tin is most widely utilized as a solder material for joining metals in joining processes. g) Zinc The oxide is heated in an electric furnace where the zinc is liberated as vapor. The vapors are then cooled in condensers to get metallic zinc. Properties Zinc possesses specific gravity is 6.2 and low melting point of 480°C. Its tensile strength is 19 to 25 MPa. It becomes brittle at 200°C and can be powdered at this temperature. It possesses high resistance to corrosion. It can be readily worked and rolled into thin sheets or drawn into wires by heating it to 100-150°C. Applications With regards to industrial applications, zinc is the fourth most utilized metal after iron, aluminum, and copper. Zinc is commonly used as a protective coating on iron and steel in the form of a galvanized or sprayed surface. It is used for generating electric cells and making brass and other alloys. The oxide of zinc is used as pigment in paints. Parts manufactured by zinc alloys include carburetors, fuel pumps, automobile parts, and so on. h) TIN Tin is recognized as brightly shining white metal. It does not corrode in wet and dry conditions. Therefore, it is commonly used as a protective coating material for iron and steel. The main source of tin is tinstone. Properties Tin is considered as a soft and ductile material. It possesses very good malleability. Its melting point is 232°C and specific gravity is 7.3. It is malleable and hence can be hammered into thin foils Applications Page 14 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  Tin-base white metals are commonly used to make bearings that are subjected to high pressure and load. Tin is used as coating on other metals and alloys owing to its resistance to corrosion. It is employed in low melting point alloys. It is generally preferred as moisture proof packing material. Because of its high malleability, it finds application in tin cans for storing food and food items. 1.1.4. Alloys An alloy is a mixture of a metal with another element, either metal or nonmetal. homogeneous combination of 2 or more elements at least one of which is a metal has metallic properties Need to improve some properties of the base metal Density, reactivity, electrical and thermal conductivity is often the same as a constituent metal Mechanical properties (strength, Young’s modulus, etc.) can be very different Comparative cost of the element components Steel: $0.27 /lb Cu: $0.76 / lb Al: $0.67 /lb Zn: 0.45 /lb (2001) $0.36 /lb $3.62 / lb $1.14 /lb 1.34 /lb (2007) A. Ferrous Alloys I. Cast Iron The cast irons are the ferrous alloys with greater that 2.14 wt. % carbon, but typically contain 3-4.5 wt. % of C as well as other alloying elements, such as silicon (~3 wt... %) which controls kinetics of carbide formation These alloys have relatively low melting points (1150-1300°C), do not formed undesirable surface films when poured, and undergo moderate shrinkage during solidification. Thus can be easily melted and amenable to casting There are four general typesof cast irons: Page 15 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright White iron has a characteristics white, crystalline fracture surface. Large amount of Fe3C are formed during casting, giving hard brittle material Gray iron has a gray fracture surface with finely faced structure. A large Si content (2-3 wt. %) promotes C flakes precipitation rather than carbide Ductileiron: small addition (0.05 wt... %) of Mg to gray iron changes the flake C microstructure to spheroidal that increases (by factor ~20) steel ductility Malleable iron: traditional form of cast iron with reasonable ductility. First cast to white iron and then heat-treated to produce nodular graphite precipitates. II. Iron and Steel First step: Fe extraction in blast furnaces (reduction reaction at ~400oC): Main iron ore: Fe2O3 Resulting raw iron is molten: Fe (~4% C) ⇒ steel-making furnace Steel: alloy of Fe and C (up to 1.2%) ⇒ oxidize impurity (S, P, etc) and C in the raw iron until the carbon content is below the required level Fe2O3 + 3 C = 2 Fe + 3 CO FeO + C = Fe + CO III. Basic ferrous alloys There are many varieties of alloy steel used in the manufacture of different types of equipment. They have greater strength and durability than carbon steel, and a given strength is secured with less material weight. Manganese steel is a special alloy steel that is always used in the cast condition (see cast steel above). Nickel, chromium, vanadium, tungsten, molybdenum, and silicon are the most common elements used in alloy steel. 1. Chromium is used as an alloying element in carbon steels to increase hardenability, corrosion resistance, and shock resistance. It imparts high strength with little loss in ductility. 2. Nickel increases the toughness, strength, and ductility of steels, and lowers the hardening temperatures so than an oil quench, rather than a water quench, is used for hardening. 3. Manganese is used in steel to produce greater toughness, wear resistance, easier hot rolling, and forging. An increase in manganese content decreases the weldability of steel. Page 16 of 93 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright 4. Molybdenum increases hardenability, which is the depth of hardening possible through heat treatment. The impact fatigue property of the steel is improved with up to 0.60 percent molybdenum. Above 0.60 percent molybdenum, the impact fatigue property is impaired. Wear resistance is improved with molybdenum content above 0.75 percent. Molybdenum is sometimes combined with chromium, tungsten, or vanadium to obtain desired properties. 5. Titanium and columbium (niobium) are used as additional alloying agents in lowcarbon content, corrosion-resistant steels. They support resistance to intergranular corrosion after the metal is subjected to high temperatures for a prolonged time period. 6. Tungsten, as an alloying element in tool steel, produces a fine, dense grain when used in small quantities. When used in larger quantities, from 17 to 20 percent, and in combination with other alloys, it produces steel that retains its hardness at high temperatures. 7. Vanadium is used to help control grain size. It tends to increase hardenability and causes marked secondary hardness, yet resists tempering. It is also added to steel during manufacture to remove oxygen. 8. Silicon is added to steel to obtain greater hardenability and corrosion resistance and is often used with manganese to obtain strong, tough steel. High-speed tool steels are usually special alloy compositions designed for cutting tools. The carbon content ranges from 0.70 to 0.80 percent. They are difficult to weld except by the furnace induction method. 9. High yield strength, low alloy structural steels (often referred to as constructional alloy steels) are special low carbon steels containing specific small amounts of alloying elements. These steels are quenched and tempered to obtain a yield strength of 90,000 to 100,000 psi (620,550 to 689,500 kPa) and tensile strength of 100,000 to 140,000 psi (689,500 to 965,300 kPa), depending upon size and shape. Structural members fabricated of these high strength steels may have smaller cross-sectional areas than common structural steels and still have equal strength. In addition, these steels are more corrosion and abrasion-resistant. In a spark test, this alloy appears very similar to the low carbon steels. Page 17 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  B. Nonferrous Alloys I. Al Alloys – Lowerdensity: 2.7g/cm3 Cu, Mg, Si, Mn, Zn additions Solid solutions or precipitation strengthened (structural aircraft parts & packaging) Cu Alloys Brass: Zn is prime impurity (costume jewelry, coins, corrosion resistant) Bronze: Sn, Al, Si, Ni are prime impurities (bushings, landing gear) Cu-Be precipitation-hardened for strength II. Ti Alloys Lower density: 4.5g/cm3 vs. 7.9 for steel Reactive at high T Space applications III. Mg Alloys very low density : 1.7g/cm3 ignites easily aircraft, missiles IV. Refractory metals high melting T Nb, Mo, W, Ta V. Noble metals Ag, Au, Pt oxidation/corrosion resistant 1. Cooper and its Alloys Cooper: soft and ductile; unlimited cold-work capacity, but difficult to machine. Cold-working and solid solution alloying Main types of Copper Alloys: –Brasses: zinc (Zn) is main substitution impurity; applications: cartridges, auto-radiator. Musical instruments, coins –Bronzes: tin (Sn), aluminum (Al), Silicon (Si) and nickel (Ni); stronger than brasses with high degree of corrosion resistance Page 18 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright –Heat-treated (precipitation hardening) Cu-alloys: beryllium coopers; relatively high strength, excellent electrical and corrosion properties BUT expensive; applications: jet aircraft landing gear bearing, surgical and dental instruments. Fig.1.1.Cooper and cooper alloys Copper’s advantages as primary metal and recycled metal, for brazed, long-life radiators and radiator parts for cars and trucks: 2. Aluminum and its Alloys Low density (~2.7 g/cm3), high ductility (even at room temperature), high electrical and thermal conductivity and resistance to corrosion but law melting point (~660°C) Main types of Aluminum Alloys: - Wrought Alloys - Cast Alloys - Others: e.g. Aluminum-Lithium Alloys Applications: form food/chemical handling to aircraft structural parts Fig.1.2.Aluminum and its Alloys 3. Magnesium and its Alloys Key Properties: Light weight Low density (1.74 g/cm3 two thirds that of aluminum) Good high temperature mechanical properties Good to excellent corrosion resistance Very high strength-to density ratios (specific strength) Page 19 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  In contrast with Al alloys that have fcc structure with (12 ) slip systems and thus high ductility, hcp structure of Mg with only three slip systems leads to its brittleness. Applications: from tennis rockets to aircraft and missiles Example: Aerospace RZ5 (Zn 3.5 - 5,0 SE 0.8 - 1,7 Zr 0.4 - 1,0 Mg remainder), MSR (AG 2.0 - 3,0 SE 1.8 - 2,5Zr 0.4 - 1,0 Mg remainder) alloys are widely used for aircraft engine and gearbox casings. Very large magnesium castings can be made, such as intermediate compressor casings for turbine engines. These include the Rolls Royce Tay casing in MSR, which weighs 130kg and the BMW Rolls Royce BR710 casing in RZ5. Other aerospace applications include auxiliary gearboxes (F16, Euro-fighter 2000, Tornado) in MSR or RZ5, generator housings (A320 Airbus, Tornado and Concorde in MSR) and canopies, generally in RZ5. Fig.1.3.Magnesium and its Alloys Gearbox Casting 4. Titanium and its Alloys (1) Titanium and its alloyshave proven to be technically superior and cost-effective materials of construction for a wide variety of aerospace, industrial, marine and commercial applications. The properties and characteristics of titanium which are important to design engineers in a broad spectrum of industries are: - Excellent Corrosion Resistance: Titanium is immune to corrosive attack by salt water or marine atmospheres. It also exhibits exceptional resistance to a broad range of acids, alkalis, natural waters and industrial chemicals. - Superior Erosion Resistance: Titanium offers superior resistance to erosion, cavitation or impingement attack. Titanium is at least twenty times more erosion resistant than the coppernickel alloys. - High Heat Transfer Efficiency: Under "in service" conditions, the heat transfer properties of titanium approximate those of admiralty brass and copper-nickel. Page 20 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  5. Other Alloys Alloys of the Co-Cr-Mo system are widely known in the world for their high physical and mechanical properties, corrosion resistance and resistance to aggressive media and critical temperature conditions. Alloys are well studied in domestic and foreign literature. The cobalt structure exists in two crystalline modifications: a low-temperature ε-phase with a hexagonal close-packed lattice and a high-temperature γ-phase with a facecentered cubic lattice. Miscellaneous Nonferrous Alloys: - Nickel and its alloy: high corrosion resistant (Example: Monel – 65Ni/28Cu/7wt%Fe – pumps valves in aggressive environment) - Lead, tin and their alloys: soft, low recrystallization temperature, corrosion resistant (Applications: solders, x-ray shields, protecting coatings) The Refractory Metals: Nb (m.p. =2468°C); Mo (°C); W (°C); Ta(3410°C) - Also: large elastic modulus, strength, hardness in wide range of temperatures - Applications: The Super alloys – possess the superlative combination of properties - Examples: - Applications: aircraft turbines; nuclear reactors, petrochemical equipment The Noble Metal Alloys: Ru(44), Rh (45), Pd (46), Ag (47), Os (75), Ir (77), Pt (78), Au (79) - expensive are notable in properties: soft, ductile, oxidation resistant - Applications: jewelry (Ag, Au, Pt), catalyst (Pt, Pd, Ru), thermocouples (Pt, Ru), dental materials etc. 1.2. Properties of metal and metal alloys Metals in general have high electrical conductivity, thermal conductivity, luster and density, and the ability to be deformed under stress without cleaving. Chemical elements lacking these properties are classed as nonmetals. A few elements, known as metalloids, sometimes behave like a metal and at other times like a nonmetal. Some examples of metalloids are as follows: boron, arsenic, and silicon. As you have already studied, metals are divided into two classes, ferrous and nonferrous. Ferrous metals are those in the iron class and are magnetic in nature. These metals consist of iron, steel, and alloys related to them. Nonferrous metals are those that contain either no, or very small amounts of, ferrous metals. Iron alloyed with various proportions of carbon gives low-, mid- and high-carbon steels, and as the carbon levels increase, ductility and toughness decrease. The addition of silicon will Page 21 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright produce cast irons, while the addition of chromium, nickel, and molybdenum to carbon steels (more than 10%) results in stainless steels. Since you will work mostly with alloys, you need to understand their characteristics. The characteristics of elements and alloys are explained in terms of physical, chemical, electrical, and mechanical properties. The basic properties of metals  Physical properties  Chemical properties  Mechanical properties  Thermal properties  Electrical properties  Magnetic properties Physical properties relate to color, density, weight, and heat conductivity. Chemical properties involve the behavior of the metal when placed in contact with the atmosphere, salt water, or other substances. Electrical properties encompass the electrical conductivity, resistance, and magnetic qualities of the metal. Mechanical properties relate to load-carrying ability, wear resistance, hardness, and elasticity when selecting stock for a job, your main concern is the mechanical properties of the metal. VI. Physical Properties The important physical properties of the metals are density, color, size and shape (dimensions), specific gravity, porosity, luster etc. Some of them are defined as under. a. Density Mass per unit volume is called as density. In metric system its unit is kg/mm3. b. Color It deals the quality of light reflected from the surface of metal. c. Size and shape Dimensions of any metal reflect the size and shape of the material. Length, width, height, depth, curvature diameter etc. determines the size. Shape specifies the rectangular, square, circular or any other section. d. Specific Gravity Page 22 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright Specific gravity of any metal is the ratio of the mass of a given volume of the metal to the mass of the same volume of water at a specified temperature. e. Porosity A material is called as porous or permeable if it has pores within it. VII. Chemical Properties The study of chemical properties of materials is necessary because most of the engineering materials, when they come in contact with other substances with which they can react, suffer from chemical deterioration of the surface of the metal. Some of the chemical properties of the metals are corrosion resistance, chemical composition and acidity or alkalinity. Corrosion is the gradual deterioration of material by chemical reaction with its environment. Corrosion in metals Corrosion may be defined as the deterioration of a material resulting from chemical attack by its environment. Since corrosion is caused by chemical reaction, the rate at which the corrosion takes place will depend to some extent on the temperature & concentration of reactants & products. Other factors such as mechanical stress & erosion may also contribute to corrosion. Most corrosion of materials refers to the chemical attack of metals that occur most commonly by electrochemical attack, since metals have free electrons, which are able to set up electrochemical cells within the metals themselves Most metals are corroded by water & the atmosphere. Metals can also be corroded by direct chemical attack for chemical solution. Most metals exist in nature in the combined state, for example, as oxides, sulfides, carbonates, or silicates, in these combined states the energies of the metals are lower. In the metallic state the energies of metals are higher, & thus there is a spontaneous tendency for metals to react chemically to form compound. Page 23 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  Fig.1.4. Mechanism of corrosion Rust is the hydrated oxide form of iron; Fe (OH) 3.Both oxygen and water are required for the formation of rust. VIII. Thermal Properties The study of thermal properties is essential in order to know the response of metal to thermal changes i.e. lowering or raising of temperature. Different thermal properties are thermal conductivity, thermal expansion, specific heat, melting point, thermal diffusivity. Melting Point Melting point is the temperature at which a pure metal or compound changes its shape from solid to liquid. It is called as the temperature at which the liquid and solid are in equilibrium. It can also be said as the transition point between solid and liquid phases. Melting temperature depends on the nature of inter-atomic and intermolecular bonds. Therefore higher melting point is exhibited by those materials possessing stronger bonds. Covalent, ionic, metallic and molecular types of solids have decreasing order of bonding strength and melting point. Melting point of mild steel is 1500°C, of copper is 1080°C and of Aluminum is 650°C. Hence matting point of metals is said to be the temperature at which metal starts to change from solid to liquid. Page 24 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  Table: 1.1 the melting points of some common metal are given below IX. Electrical Properties The various electrical properties of materials are conductivity, temperature coefficient of resistance, dielectric strength, resistively, and thermoelectricity. These properties are defined as under. a. Conductivity Conductivity is defined as the ability of the material to pass electric current through it easily i.e. the material which is conductive will provide an easy path for the flow of electricity through it. b. Temperature Coefficient of Resistance It is generally termed as to specify the variation of resistively with temperature. c. Dielectric Strength It means insulating capacity of material at high voltage. A material having high dielectric strength can withstand for longer time for high voltage across it before it conducts the current through it. d. Resistivity It is the property of a material by which it resists the flow of electricity through it. e. Thermoelectricity If two dissimilar metals are joined and then this junction is heated, a small voltage (in the mill-volt range) is produced, and this is known as thermoelectric effect. Page 25 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  X. Mechanical Properties Under the action of various kinds of external forces, the behavior of the material is studied that measures the strength and lasting characteristic of a material in service. The mechanical properties of materials are of great industrial importance in the design of tools, machines and structures. The mechanical properties of the metals are those which are associated with the ability of the material to resist mechanical forces and load. The main mechanical properties of the metal are strength, stiffness, elasticity, plasticity, ductility, malleability, toughness, brittleness, hardness, formability, cast ability and weld ability. a. Elasticity or Proof stress It is defined as the property of a material to regain its original shape after deformation when the external forces are removed. It can also be referred as the power of material to come back to its original position after deformation when the stress or load is removed. It is also called as the tensile property of the material. b. Plasticity Plasticity is defined the mechanical property of a material which keep the deformation produced under load permanently. This property of the material is required in forging, in stamping images on coins and in ornamental work. It is the ability or tendency of material to undergo some degree of permanent deformation without its rupture or its failure. Plastic deformation takes place only after the elastic range of material has been exceeded. Such property of material is important in forming, shaping, extruding and many other hot or cold working processes. Materials such as clay, lead, etc. are plastic at room temperature and steel is plastic at forging temperature. This property generally increases with increase in temperature of materials. c. Strength Strength is defined as the ability of a material to sustain loads without undue distortion or failure. The internal resistance offered by a material to an externally applied force is called stress. The capacity of bearing load by metal and to withstand destruction under the action of external loads is known as strength. The stronger the material the greater the load it can withstand. Page 26 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright This property of material therefore determines the ability to withstand stress without failure. Strength varies according to the type of loading. It is always possible to assess tensile, compressive, shearing and tensional strengths. The maximum stress that any material can withstand before destruction is called its ultimate strength.. d. Toughness The ability of material to with stand bending or the application of shear stresses without fracture. By this definition, copper is extremely tough but cast iron is not. Strong materials are generally tough although ductility has a more pronounced effect in determining toughness. Toughness the ability to absorb energy up to fracture. e. Stiffness It is defined as the ability of a material to resist deformation under stress. The resistance of a material to elastic deformation or deflection is called stiffness or rigidity. A material that suffers slight or very less deformation under load has a high degree of stiffness or rigidity. That means, the steel beam is stiffer or more rigid than aluminum beam. A material which deforms less under a given load is stiffer than one which deforms more. f. Ductility Ductility is the capacity of a material to undergo deformation under tension without rupture as in a wire drawing operation. A ductile material must be strong and plastic. The ductility is usually measured by the terms, percentage elongation and percent reduction in area which is often used as empirical measures of ductility. The materials those possess more than 5% elongation are called as ductile materials. The ductile material commonly used in engineering practice are mild steel, copper, aluminum, nickel, zinc, tin and lead. g. Malleability Malleability is the ability of the material to be flattened into thin sheets under applications of heavy compressive forces without cracking by hot or cold working means. It is capacity of a material to withstand deformation under compression without rupture. A malleable material should be plastic but it is not essential to be so strong. h. Hardness Hardness is defined as the ability of a metal to cut another metal. A harder metal can always cut or put impression to the softer metals by good quality of its hardness. It holds many Page 27 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright different properties such as resistance to wear, scratching, deformation and mach inability etc. i. Brittleness Brittleness is the property of a material opposite to ductility. It is the property of breaking of a material with little permanent distortion. The materials having less than 5% elongation under loading behavior are said to be brittle materials. Brittle materials when subjected to tensile loads snap off without giving any sensible elongation. Glass, cast iron, brass and ceramics are considered as brittle material. j. Wear: - Is a complex surface phenomenon that results in mechanical attrition of moving surfaces in contact, by welding and removal of particles through friction? k. Yield Stress: The strength of a material is the property of resistance to external loads or stresses while not causing structural damage. The strongest substance known is tungsten molybdenum; titanium and nickel follow in order of strength of commercially pure metals. Pure iron is much weaker, but, when alloyed with the chemical element known as “carbon" to make steel, it may then become stronger than any of the pure metals except tungsten. l. Creep When a metal part is subjected to a high constant stress at high temperature for a longer period of time, it will undergo a slow and permanent deformation (in form of a crack which may further circulate further towards creep failure) called creep. Properties and applications of metals are: Extremely good conductors of electricity and heat, Not transparent to visible light, A polished metal surface has a lustrous appearance, Atoms arranged in a regular repeating structure (crystalline), Relatively good strength Dense Malleable or ductile: high plasticity Resistant to fracture: tough Some of the metals (Fe, Co, and Ni) have desirable magnetic properties. Opaque to visible light Page 28 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  Shiny appearance 1.3. Metal Identification Methods Metals play a prominent part in our everyday lives. Some metals do not have all of these features. For example, mercury (Hg) is a liquid at room temperature, but has a high luster, and conducts heat and electricity easily. Part of the metalworker’s skill lies in the ability to identify various metal products brought to the shop. Identifying steels All steels look very much alike. Thus, it is difficult to identify by looking at it. There are three methods of identification. A. Number system B. Color code C. Spark test A. Number system, A number system to identify steel has been developed by the American Iron and Steel Institute (AISI) and the Society of Automotive Engineering’s (SAE). The systems are based on the use of numbers composed of four digits.] I. The first number tells the kind of steel: shows carbon steel shows nickel steel shows nickel-chromium steel shows molybdenum steel Show chromium steel and so on. II. The second number in alloy steel shows the approximate percent of alloy elements. For example, SAE 2320 shows a nickel steel with about 3% nickel. III. The last two numbers shows the carbon content in points. For example, SAE 2320 is a nickel steel with 20 point of carbon. B. Color code, Page 29 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright Most manufacturers paint each different kind of steels a different color. Some paint only the ends. Others paint all along the bar. If certain steel is painted red, it may mean that it is high carbon steel. There are several Metal Identification Methods used to identify a piece of metal. i. The primary method is Visual Fig.1.5.Visual Identification Metal ii. Magnetic Test..... The Magnetic Test is another method used to aid in the general identification of metals. Some metals are nonmagnetic. Generally ferrous metals are magnetic, and nonferrous metals are non-magnetic. This test is not 100 % accurate because some stainless steels are nonmagnetic. In this instance, there is no substitute for experience. iii. File Test. One simple way to check for hardness in a piece of metal is to file a small portion of it. If it is soft enough to be machined with regular tooling, the file will cut it. If it is too hard to machine, the file will not cut it. Observe relative ease of filing a. Soft metal files easily, the file bites into the metal. b. File slides over the surface of hard metal easily. Fig.1.6. File Test iv. Spark Test..... A. Observe sparks at grinding wheel under subdued light a) Grinding wheel should be clean b) Pressure on metal should be medium and uniform Page 30 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  c) Compare known samples to unknown samples B. Observe a) Spark Color b) Length of spark lines c) Number of explosions d) Explosion shape C. It is an accurate method of identification a) Sparks occur relative to oxidation of the heated metal particles b) Iron does not oxidize rapidly therefore the spark lines are long and fade outwith cooling c) High carbon steels have a spark with short lines and many explosion Bench Grinders or portable Grinders Fig.1.7: Grinding Spark Test. v. Chip Test The chip test is done by removing a small amount of material from the test piece with a sharp, cold chisel. The Chip Test shows chips from small, broken fragments to a continuous strip. The chip may have smooth, sharp edges or it may be coarse or fine-grained. The chip may have saw tooth edges. The chip size is important in identifying the metal. The ease of the chipping process is a factor in identifying the metal. vi. Appearance Test This test includes such things as the color and appearance of machined as well as unmachined surfaces. SELF CHECK UNIT PART: I Write “TRUE” if the statement is correct and “FALSE” if it is wrong statement. Page 31 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  1. High carbon steel provides high hardness and strength. 2. A ferrous and non-ferrous metal contains iron in their chemical compounds. 3. The copper is one of the most common non-ferrous metals. 4. Nickel is an example of non-ferrous metal. PART: II Choose the correct answer for the following questions. 1. One of the following is not the classification of metals A. Ferrous metals B. Non-ferrous metals C. Ferrous alloys D. Non-ferrous alloys E. None 2. The basic principle raw material for all ferrous metal is A. Pig iron B. Cast iron C. Malleable iron D. All 3. Grey pig iron contains about _______% carbon in free form A. 4 % B. 3% C. 1% D. 2% 4. Which one of the following is correct about grey cast iron and white iron? A. Low in cost B. Very brittle C. cannot hammered D. All 5. Which one of the following is not correct about low carbon steel is A. Have a lower tensile strength and hardness B. It is easy welded machined, and formed C. It is used for most bench metal D. None 6. Which one the following is not true about the properties of aluminum A. Good electrical conductivity B. Malleable and ductile C. Low thermal conductivity D. Resistance to corrosion 7. Copper is mainly used in A. Making electric cables and wires for electric machinery B. Motor winding C. Electroplating D. All 8. Bronze is commonly an alloy of A. Copper and Aluminum B. copper and Tin C. Copper and Zinc D. Tin and Zinc 9. Which one of the following is not correct about mechanical properties of materials? A. Elasticity B. plasticity C. Density D. Strength 10. Which one of the following is true about metal identification? A. Magnetic test B. Visual test C. Spark test D. all 11. The ability of a metal to resist being pulled apart by opposing forces acting in a straight Page 32 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright  line is A.Shear strength C. shear stress B.Tensile strengthD. Compressive strength 12. The ability of a material to resist penetration and wear by another material is named A. Hardness C. Fatigue B.BrittlenessD. Toughness PART: III Match the following items from column “B” to “A” with their meanings and write your answer on the space provided. (10 %) Column A Column B 1. Non-ferrous metal A. steel 2. Bronze B. an alloy of CU and Zn 3. Solder C. an alloy of lead and tin 4. Brass D. an alloy of CU and Sn 5. Ferrous metal E. Aluminum 6. Elasticity F.The property of breaking without warning 7. Ductility G. A combination of high strength and medium ductility 8. Malleability H. The capacity to be rolled or hammered into thin sheets 9. Toughness I. The capacity to be drawn from a larger to a smaller Diameter of wire 10. Brittleness J.The ability of material to return to its original size, shape Anddimension Page 33 of 39 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright Page 89 of 93 Ministry of Labor and Testing and Identifying Properties of Version -1 Skills Metals August , 2022 Author/Copyright