Lecture 5 - KDJ10603 - Alloy Steel PDF

KDJ10603 FERROUS & NON FERROUS METALS ALLOY STEEL EN. MOHAMED FAISOL BIN MOHAMED NOR EN. RUHIYUDDIN BIN MOHD ZAKI FACULTY OF CHEMICAL ENGINEERING & TECHNOLOGY  Grey Cast Iron...

KDJ10603 FERROUS & NON FERROUS METALS ALLOY STEEL EN. MOHAMED FAISOL BIN MOHAMED NOR EN. RUHIYUDDIN BIN MOHD ZAKI FACULTY OF CHEMICAL ENGINEERING & TECHNOLOGY  Grey Cast Iron (free form graphite) White Cast Iron (carbon formed Fe 3C) Malleable Cast Iron Cast Iron (White cast iron rendered by annealing) (1.7 < x < 3%) Spheroidal/Nodular C.Iron (free form graphite in sphere/nodular) Iron Wrough Iron Austenite Cast Iron (graphite formed either in ‘flake’ or (x > 3%) ‘nodular’) Abrasion resistant Cast Iron (alloy cast iron) Steel (x < 1.7 ) Plain carbon steel (0.05 < x < 0.90) Mo Ni Dead mild carbon steel S Cr Tools steel (0.05 < x < 0.15) (0.90 < x < 1.40) Mild carbon steel (0.10 < x < 0.30) Mn W Medium carbon steel Alloying elements (0.30 < x < 0.60) V Co High carbon steel (0.60 < x < 0.90)  Steels Low Alloy High low carbon Med carbon high carbon Alloy 1.65%Mn, > 0.60% Si, or >0.60% Cu Most common alloy elements: – Chromium, nickel, molybdenum, vanadium, tungsten, cobalt, boron, and copper. Low alloy: Added in small percents (20%) – i.e. > 10.5% Cr = stainless steel where Cr improves corrosion resistance and stability at high or low temps  Alloying Elements used in Steel Manganese (Mn) combines with sulfur to prevent brittleness >1% – increases hardenability 11% to 14% – increases hardness – good ductility – high strain hardening capacity – excellent wear resistance Ideal for impact resisting tools  Alloying Elements used in Steel Sulfur (S) Imparts brittleness Improves machineability Okay if combined with Mn Some free-machining steels contain 0.08% to 0.15% S Examples of S alloys: – 11xx – sulfurized (free-cutting)  Alloying Elements used in Steel Nickel (Ni) Provides strength, stability and toughness, Examples of Ni alloys: – 30xx – Nickel (0.70%), chromium (0.70%) – 31xx – Nickel (1.25%), chromium (0.60%) – 32xx – Nickel (1.75%), chromium (1.00%) – 33XX – Nickel (3.50%), chromium (1.50%)  Alloying Elements used in Steel Molybdenum (Mo) Usually < 0.3% increase hardenability and strength Mo-carbides help increase creep resistance at elevated temps – typical application is hot working tools  Alloying Elements used in Steel Chromium (Cr) Usually < 2% increase hardenability and strength Offers corrosion resistance by forming stable oxide surface typically used in combination with Ni and Mo – 30XX – Nickel (0.70%), chromium (0.70%) – 5xxx – chromium alloys – 6xxx – chromium-vanadium alloys – 41xxx – chromium-molybdenum alloys  Alloying Elements used in Steel Vanadium (V) Usually 0.03% to 0.25% increase strength – without loss of ductility  Alloying Elements used in Steel Tungsten (W) helps to form stable carbides increases hot hardness – used in tool steels  Alloying Elements used in Steel Silicon (Si) About 2% increase strength without loss of ductility enhances magnetic properties  Alloying Elements used in Steel Copper (Cu) 0.10% to 0.50% increase corrosion resistance Reduced surface quality and hot-working ability used in low carbon sheet steel and structural steels  Alloying Elements used in Steel Boron (B) for low carbon steels, can drastically increase hardenability improves machinablity and cold forming capacity  Alloying Elements used in Steel Aluminum (Al) deoxidizer 0.95% to 1.30% produce Al-nitrides during nitriding  Selecting Steels High-Strength Low-Alloy Structural Steel Microalloyed Steel Free-Machining Steel Bake-Hardenable Steel Sheet Precoated Steel Sheet Electrical and Magnetic Applications Maraging Steel High-Temperature Steel Stainless Steel Tool Steel  Alloy Steel Low Alloy Steel A low-alloy steel is a type of metal mixture composed of steel and another metals that possess desirable properties. Low-alloy steel contains about 1%-5% of alloying elements. Therefore, it possesses precise chemical compositions that provide better mechanical properties that are intended to prevent corrosion.  Low-alloy steels typically undergo heat treatment, normalizing and tempering during production. They are also weldable. However, weld heat treatment is necessary in order to avoid weld cracking. Significant advantages of low-alloy steels over mild steel are: High yield strength Able to withstand high temperatures Good creep strength Oxidation resistance Hydrogen resistance Low temperature ductility Type of Low Alloy Steel High-strength low-alloy steel (HSLA) Type of alloy steel that provides better mechanical properties or greater resistance to corrosion than carbon steel. HSLA steels vary from other steels in that they are not made to meet a specific chemical composition but rather specific mechanical properties. They have a carbon content between 0.05 and 0.25% to retain formability and weldability. Other alloying elements include up to 2.0% manganese and small quantities of copper, nickel, niobium, nitrogen, vanadium, chromium, molybdenum, titanium, calcium, rare-earth elements, or zirconium Low carbon steel alloy type.  Principal low-alloy steels SAE designation Composition 13xx Mn 1.75% 40xx Mo 0.20% or 0.25% or 0.25% Mo & 0.042% S 41xx Cr 0.50% or 0.80% or 0.95%, Mo 0.12% or 0.20% or 0.25% or 0.30% 43xx Ni 1.82%, Cr 0.50% to 0.80%, Mo 0.25% 44xx Mo 0.40% or 0.52% 46xx Ni 0.85% or 1.82%, Mo 0.20% or 0.25% 47xx Ni 1.05%, Cr 0.45%, Mo 0.20% or 0.35% 48xx Ni 3.50%, Mo 0.25% 50xx Cr 0.27% or 0.40% or 0.50% or 0.65% 50xxx Cr 0.50%, C 1.00% min 50Bxx Cr 0.28% or 0.50%, and added boron 51xx Cr 0.80% or 0.87% or 0.92% or 1.00% or 1.05% 51xxx Cr 1.02%, C 1.00% min 51Bxx Cr 0.80%, and added boron 52xxx Cr 1.45%, C 1.00% min 61xx Cr 0.60% or 0.80% or 0.95%, V 0.10% or 0.15% min 86xx Ni 0.55%, Cr 0.50%, Mo 0.20% 87xx Ni 0.55%, Cr 0.50%, Mo 0.25% 88xx Ni 0.55%, Cr 0.50%, Mo 0.35% 92xx Si 1.40% or 2.00%, Mn 0.65% or 0.82% or 0.85%, Cr 0.00% or 0.65% 94Bxx Ni 0.45%, Cr 0.40%, Mo 0.12%, and added boron ES-1 Ni 5%, Cr 2%, Si 1.25%, W 1%, Mn 0.85%, Mo 0.55%, Cu 0.5%, Cr 0.40%, C 0.2%, V 0.1%  Alloy Steel High Alloy Steel High alloy steel is an alloy of iron which contains 10.5% of chromium. High alloy steel also has a mixture of 10% alloy. Chromium makes a thin layer of oxide on the surface of the steel and it is known as latent layer. And it is little costly than low alloy steel. To give austenitic nature to the steel, high level of carbon and manganese are added. The expanding measure of chromium provides an expanded protection from erosion. High alloyed steel can prevent consumption due to the high chromium content. High alloy steel additionally contains limits of manganese, silicon and carbon. It is utilized for the benefit in exceptional hot gasses and fluids on different components at high temperatures. For example molybdenum and nickel can be added to grant other helpful properties such as to improve formability and expanded consumption protection. Type of High Alloy Steel Stainless Steels (Corrosion-Resistant Steels) – contain at least 10.5% Chromium – trade name AISI assigns a 3 digit number – 200 and 300 … Austenitic Stainless Steel – 400 … Ferritic or Martensitic Stainless Steel – 500 … Martensitic Stainless Steel  Stainless Steel Steel alloyed with chromium (18%), nickel (8%), magnesium (8%) Hard and tough Corrosion resistance Comes in different grades Sinks, cooking utensils, surgical instruments 26  Stainless Steels Main types: Ferritic chromium: very formable, relatively weak; used in architectural trim, kitchen range hoods, jewelry, decorations, utensils Grades 409, 430, and other 400 Austentitic nickel-chromium: non-magnetic, machinable, weldable, relatively weak; used in architectural products, such as fascias, curtain walls, storefronts, doors & windows, railings; chemical processing, food utensils, kitchen applications. series. Grades 301, 302, 303, 304, 316, and other 300 series. 27  Martensitic chromium: High strength, hardness, resistance to abrasion; used in turbine parts, bearings, knives, cutlery and generally Magnetic. Grades 17-4, 410, 416, 420, 440 and other 400 series 28  Alloy Steel Tool Steel Refers to a variety of carbon and alloy steels that are particularly well-suited to be made into tools. Characteristics include high hardness, resistance to abrasion (excellent wear), an ability to hold a cutting edge, resistance to deformation at elevated temperatures (red-hardness). Tool steel are generally used in a heat-treated state. High carbon content – very brittle High carbon steel type  6 Types of Tool Steel AISI-SAE tool steel grades Defining property AISI-SAE grade Significant characteristics Water-hardening W O Oil-hardening Cold-working A Air-hardening; medium alloy D High carbon; high chromium Shock resisting S T Tungsten base High speed M Molybdenum base H1-H19: chromium base Hot-working H H20-H39: tungsten base H40-H59: molybdenum base Plastic mold P L Low alloy Special purpose F Carbon tungsten  The choice of group to select depends on cost, working temperature, required surface hardness, strength, shock resistance, and toughness requirements. The more severe the service condition (higher temperature, abrasiveness, corrosiveness, loading), the higher the alloy content and consequent amount of carbides required for the tool steel. 1. Water-hardening group W-group tool steel gets its name from its defining property of having to be water quenched. W-grade steel is essentially high carbon plain-carbon steel. This group of tool steel is the most commonly used tool steel because of its low cost compared to others. They work well for parts and applications where high temperatures are not encountered; above 150 °C (302 °F) it begins to soften to a noticeable degree. Its hardenability is low, so W-group tool steels must be subjected to a rapid quenching, requiring the use of water. These steels can attain high hardness (above HRC 66) and are rather brittle compared to other tool steels. 2. Cold-work group The cold-work tool steels include the O series (oil-hardening), the A series (air-hardening), and the D series (high carbon-chromium). These are steels used to cut or form materials that are at low temperatures. This group possesses high hardenability and wear resistance, and average toughness and heat softening resistance. They are used in production of larger parts or parts that require minimal distortion during hardening. 3. Shock-resisting group The high shock resistance and good hardenability are provided by chromium-tungsten, silicon-molybdenum, silicon-manganese alloying. Shock-resisting group tool steels (S) are designed to resist shock at both low and high temperatures. A low carbon content is required for the necessary toughness (approximately 0.5% carbon). Carbide-forming alloys provide the necessary abrasion resistance, hardenability, and hot-work characteristics. This family of steels displays very high impact toughness and relatively low abrasion resistance and can attain relatively high hardness (HRC 58/60) 4. High Speed Steel (HSS) Medium Carbon steel alloyed with Tungsten, chromium, vanadium Very hard Resistant to frictional heat even at high temperature Can only be ground Machine cutting tools (lathe and milling) Drills 35 Molybdenum High Speed Steels (HSS) Combining molybdenum, tungsten and chromium steel creates several alloys commonly called "HSS", measuring 63–65 Rockwell "C" hardness. Cobalt High Speed Steels (HSS) The addition of cobalt increases heat resistance, and can give a Rockwell hardness up to 70 HRC. 5. Hot-working group Hot-working steels are a group of steel used to cut or shape material at high temperatures. H-group tool steels were developed for strength and hardness during prolonged exposure to elevated temperatures. These tool steels are low carbon and moderate to high alloy that provide good hot hardness and toughness and fair wear resistance due to a substantial amount of carbide 6. Special-purpose group P-type tool steel is short for plastic mold steels. They are designed to meet the requirements of zinc die casting and plastic injection molding dies. L-type tool steel is short for low alloy special purpose tool steel. L6 is extremely tough. F-type tool steel is water hardened and substantially more wear resistant than W-type tool steel.  Alloy Steel Microalloyed Steel Type of alloy steel that contains small amounts of alloying elements (0.05 to 0.15%), including niobium, vanadium, titanium, molybdenum, zirconium, boron, and rare-earth metals. They are used to refine the grain microstructure or facilitate precipitation hardening. microalloyed steels are between a carbon steel and a low alloy steel. Their yield strength is between 275 and 750 MPa (40 and 110 ksi) without heat treatment. Weldability is good, and can even be improved by reducing carbon content while maintaining strength.  Fatigue life and wear resistance are superior to similar heat-treated steels. The disadvantages are that ductility and toughness are not as good as quenched and tempered (Q&T) steels. They must also be heated hot enough for all of the alloys to be in solution; after forming, the material must be quickly cooled to 540 to 600 °C (1,004 to 1,112 °F) Cold-worked microalloyed steels do not require as much cold working to achieve the same strength as other carbon steel; this also leads to greater ductility. Hot-worked microalloyed steels can be used from the air-cooled state. If controlled cooling is used, the material can produce mechanical properties similar to Q&T steels. Machinability is better than Q&T steels because of their more uniform hardness and their ferrite-pearlite microstructure  Because microalloyed steels are not quenched and tempered, they are not susceptible to quench cracking, nor do they need to be straightened or stress relieved. However, because of this, they are through-hardened and do not have a softer and tougher core like quench and tempered steels  Alloy Steel Maraging Steel Maraging (super alloys): High strength, high Temperature alloy used in structural applications, aircraft components and are generally magnetic. Alloys containing around 18% Nickel.  Maraging steels are ultra-high-strength steel alloys, a special class of low-carbon steel, that exhibit superior strength and toughness compared to most other steels, yet have a similar ductility. ‘Maraging’ is a term derived from martensitic and ageing, referring to the process by which the steel is strengthened. Some of the most advantageous properties of maraging steels include: High yield strength and ultimate tensile strength High toughness High ductility High impact strength High fatigue strength Workability High resistance to crack propagation Weldability Heat treatment features Low coefficient of thermal expansion  Other of Alloy Carbon Steels Used in Construciton Those steels in which the residual elements (carbon, manganese, sulphur, silicon, etc.) are controlled, but in which no alloying elements are added to achieve special properties. A36Carbon Structural Steel: the workhorse all-purpose steel for nearly all structural “shapes” (beams, channels, angles, etc.), as well as plates and bars,  Wide Flanged Beams “W” shapes: A36 has been displaced as the steel of choice for the major “shape” subcategory called wide-flange beams, or “W” shapes. The replacement steel is a high-strength, low-alloy steel, known as A992. For the other non-wide-flange beam structural shapes, A36 remains the predominant steel.  Structural pipe and square tubing Pipe: A53 Pipe, Steel, Black and Hot-Dipped, Zinc- Coated Welded and Seamless. Tubing: A500 Cold-Formed Welded and Seamless Structural Tubing in Rounds and Shapes. A501 Hot-Formed Welded and Seamless Carbon Steel Structural Tubing.