CE1201 Properties of Materials - Testing Concepts Lecture Slides 2024

CE1201- Properties of Materials Types of Materials  WHY IS LEARNING ABOUT MATERIALS IMPORTANT a key decision for most engineering applications. This module exposes the student to the world of materials for engineering purposes. They will gain knowledge about Different classes...

CE1201- Properties of Materials Types of Materials  WHY IS LEARNING ABOUT MATERIALS IMPORTANT a key decision for most engineering applications. This module exposes the student to the world of materials for engineering purposes. They will gain knowledge about Different classes of material Their material properties considered in engineering decisions The testing Some insights material selection criteria for simple engineering applications.  LEARNING OUTCOMES (LOs) LO 1:Recognize the existence of different types of engineering materials LO 2: Explain the basic structure of materials and how properties of materials are related to basic structure LO 3:Demonstrate the knowledge of testing concepts to determine properties of engineering materials LO 4:Test samples of metals to determine the properties that characterize their behavior under external loads LO 5: Select materials for simple engineering applications  TO GAIN LO 1 First part:- Types of materials available & their engineering applications Metals, alloys, ceramics, polymers, rubber, plastics, timber, cement, sand, silicon, glass, rock aggregates, clay Etc. Second Part:- New engineering materials and Adhesives EVALUATION OF ENGINEERING MATERIALS GENERAL CLASSIFICATION FOR MATERIALS USED IN ENGINEERING Engineering materials Metals Non-Metals Polymers Semi Ferrous Non-ferrous (Plastics & Ceramics Composites conductors Rubber)  METALS ❖ Composed of one or more metallic elements (e.g., iron, aluminum, copper, titanium, gold, nickel), ❖ often also non-metallic elements (e.g., carbon, nitrogen, oxygen) in relatively small amount ❖ Relatively dense  METALS ❖ Show good mechanical properties relatively stiff, strong and ductile (i.e., capable of large amounts of deformation without fracture), resistant to fracture which accounts for their widespread use in structural applications ❖ extremely good conductors of electricity and heat ❖ not transparent to visible light ❖ some of the metals (i.e., Fe, Co, and Ni) have desirable magnetic properties Note:- when pure, are soft and easily deformed They can be made strong by alloying and by mechanical and heat treatment  FURTHER CLASSIFICATION OF METALS Metals Ferrous metals & Alloys Non-Ferrous metals & Alloys Alloys (Non-Fe Alloys (Fe + other Ferrous Metals Non-Ferrous Metals + other elements) elements) High Wrought Stainless Silicon Zn Cast iron Steel speed Cu Al Brass Bronze iron steel steel steel Alloys:- Combination of a metal with at least one other metal or non-metal Ferrous metals & alloys  1. CAST IRON ❖ Produced by smelting iron-carbon alloys that have a carbon content greater than 2%. ❖ After smelting, the metal is poured into a mold. Not worked with hammers and tools ❖ Contains 2–4% carbon, and 1–3% of silicon (which improves the casting performance of the molten metal), small amounts of manganese and some impurities like sulfur and phosphorous present. Cast Iron Nodular Malleable cast Grey cast Iron White cast Iron (Ductile) cast iron iron  GREY CAST IRON ❖ By far the oldest and most common form of cast iron. ❖ Named because its fracture has a gray appearance, consists of carbon in the form of flake graphite in a matrix consisting of ferrite, pearlite or a mixture of the two. Add C, Si (1-3%), Mn, S, P Cooling Graphite forms formed during cooling Melted iron https://sciencestruck.com/properties-of-cast-iron https://www.researchgate.net/figure/Microstructure-of-Gray-Cast-Irons-a-un-etched-and-b-etched-conditions-for-Fe-C-Si_fig1_260789968  GREY CAST IRON Characteristics A better thermal conductor Has a higher level of vibration damping (damping capacity that is 20–25 times higher than steel and superior to all other cast irons) Easier to machine than other cast irons Not as ductile as other forms of cast iron Highly resistance to rust  GREY CAST IRON Applications https://www.reliance-foundry.com/blog/cast-iron https://www.slideshare.net/SayanDas72/various-types-of-engineering-cast-iron  GREY CAST IRON https://www.reliance-foundry.com/blog/cast-iron https://www.slideshare.net/SayanDas72/various-types-of-engineering-cast-iron  WHITE CAST IRON ❖ is unique in that it is the only member of the cast iron family in which carbon is present only as carbide. The cementite in white cast iron forms during the cooling process (rapid cooling). The carbon in the iron does not have time to combine with oxygen in the air to form carbon dioxide, so it remains in the iron as cementite. The cementite forms as a network of interlocking crystals, which gives white cast iron its high hardness and brittleness.  WHITE CAST IRON Characteristics ❖ Due to the absence of graphite, it has a light appearance. ❖ The presence of different carbides, depending on the alloy content, makes white cast irons extremely hard and abrasion resistant but very brittle. ❖ It has lower silicon content and low melting point. ❖ The carbon present in the white cast iron precipitates and forms large particles that increase the hardness of the cast iron. ❖ It is abrasive resistant as well as cost- effective making them useful in various applications like lifter bars and shell liners in grinding mills, wear surfaces of pumps, balls and rings of coal pulverisers, etc.  WHITE CAST IRON Application Brake rotors Gears Bearings Dies Moulds Mining equipment Cement mill rolls  MALLEABLE CAST IRON ❖Malleable iron Unlike Gray and Ductile Iron, Malleable Iron is cast as a carbide or white iron and an annealing or "malleablizing" heat treatment is required to convert the carbide into graphite. ❖The presence of graphite in a more compact or sphere-like form gives Malleable Iron ductility and strength almost equal to cast, low-carbon steel. ❖The formation of carbide during solidification results in the conventional shrinkage behaviour of Malleable Iron and the need for larger feed metal reservoirs, causing reduced casting yield and increased production costs. ❖Two types of Malleable Iron Depending on Annealing treatments,  MALLEABLE CAST IRON ▪Types ▪Ferritic Malleable Cast iron – Depends on C and Si. 1st stage 2 to 36 hours at 940˚C in a controlled atmosphere – Cool rapidly to 750˚C & hold for 1 to 6 hours ▪Pearlite malleable iron – 1st stage 2 to 36 hours at 940˚C in a controlled atmosphere – Cool to 870˚C slowly, then air cool & temper to specification  MALLEABLE CAST IRON Characteristics ❖Excellent machinability ❖Significant ductility ❖Good shock resistance properties Applications connecting rods and universal joint yokes, transmission gears, differential cases and certain gears, compressor crankshafts and hubs, flanges, pipe fittings and valve parts for railroad, marine and other heavy-duty applications  NODULAR (DUCTILE) CAST IRON ❖is yet another type of ferrous alloy that is used as an engineering material in many applications. ❖To produce ductile iron, small amount of magnesium is added to the molten iron, which alters the graphite structure that is formed. The magnesium reacts with oxygen and sulphur in the molten iron leading to nodule shaped graphite that has earned them the name-nodular cast iron. https://www.reliance-foundry.com/blog/cast-iron https://www.slideshare.net/SayanDas72/various-types-of-engineering-cast-iron Characteristics NODULAR (DUCTILE) CAST IRON ❖Strength higher than grey cast iron ❖Ductility up to 6% as cast or 20% annealed ❖Low cost-simple manufacturing process makes complex shapes ❖Machineability better than steel ❖Ductile cast iron offers significantly low shrinkage during casting. Applications Automotive industry are the major user of ductile iron castings. Crankshafts, front wheel spindle supports, steering knuckles, disc brake callipers Water pipe and pipe fittings industry https://www.reliance-foundry.com/blog/cast-iron https://www.slideshare.net/SayanDas72/various-types-of-engineering-cast-iron  2. WROUGHT IRON ❖ Wrought iron is an iron alloy with a very low carbon content (less than 0.08%) in contrast to that of cast iron (2.1% to 4%). ❖ Puddling furnace is used to produce wrought iron ❖ In the puddling furnace Pig Iron is melted while removing the other impurities by oxidization and virtually Carbon free ❖ Remaining Iron forms a plastic mass formed into a ball by a puddling bar Characteristics Wrought iron is made by heating iron ore in a ❖ Hard furnace until it melts. The molten iron is then ❖ Ductile poured into a mold and allowed to cool. Once ❖ Corrosion resistant the iron has cooled, it is heated again and ❖ Excellent weldability hammered repeatedly. This process removes impurities from the iron and makes it stronger.  2. WROUGHT IRON Applications Gates Furniture Home decorate items Rivets, bolts, chains etc  3. STEEL ❖ Steel may be Plain Carbon (iron and carbon only) or alloys containing less than 2% carbon ❖ Steel is obtained by refining pig iron ❖ The Bessemer converter, open hearth furnace, electric arc furnace can be used to produce steel ❖ Three main types as, Steel Medium carbon High carbon Low carbon steel steel steel (0.08