Download Metallurgy and Materials Science: Mechanical Properties and Testing and more Exams Engineering in PDF only on Docsity!
3A1 Chapter 13: Metallurgy & Materials
questions well answered to pass
Mechanical property - correct answer ✔✔Properties of a material that predict how material will behave under loads Mechanical properties of a material depend on: - correct answer ✔✔-Composition -Grain structure Property that determines whether material will break or stretch under force ex. cast iron - correct answer ✔✔Brittleness Materials resistance to wear, abrasion and penetration ex. diamond - correct answer ✔✔Hardness Measure of how much material can be stretched under tensile load without fracturing above elastic limit Opposite being brittle ex. copper - correct answer ✔✔Ductility What happens to a material when its being stretched causing a reduction in the cross sectional area - correct answer ✔✔Necking Materials ability to deform by compression without cracking or rupturing Hammered (cold) into various shapes Increases when material heated - correct answer ✔✔Malleability Materials ability to return to its original shape when load is removed - correct answer ✔✔Elasticity
Material is said to be _______ if its soft and easily deformed Doesn't return to original shape - correct answer ✔✔Plasticity Determines materials ability to withstand sudden impact/hard blow - correct answer ✔✔Toughness Toughness is also known as - correct answer ✔✔Impact strength Determines mechanical behaviour of material under static loading conditions - correct answer ✔✔Tention testing Tension testing provides measurement of _________ & ___________ properties of materials - correct answer ✔✔elastic and plastic Ratio of applied load to original cross sectional area - correct answer ✔✔Nominal stress Nominal strain - correct answer ✔✔Ration of elongation to original length How is elongation determined in tension test? - correct answer ✔✔By measuring change in distance between 2 gauge points Distance between gauge points of unstressed specimen - correct answer ✔✔5cm What is the slope defined as on a stress/strain diagram - correct answer ✔✔Young's Modulus of Elasticity What does Young's Modulus of elasticity measure? - correct answer ✔✔Stress required to cause strain deformation When this point is reached, specimen will no longer return to original shape - correct answer ✔✔Yield Point/Elastic limit
-10kg load -90kg load applied (100kg total) -Dial measures depth Describe C reading Rockwell Test - correct answer ✔✔-Hard materials -Materials greater than 100HR -Diamond cone -150kg load Describe components of following Rockwell Hardness number HRA3 - correct answer ✔✔HR - Hardness Rockwell A - scale used 3 - hardness number Similar to Brinell test but indenter is pyramidal, leaves square indentation - correct answer ✔✔Vickers Test Describe components of following Vickers Test number 300HV50 - correct answer ✔✔300 - hardness number HV - scale used 50 - load used Hardness test used for brittle or thin materials - correct answer ✔✔Knoop Test What is unique about Knoop Test compared to other hardness tests - correct answer ✔✔-Microscopic measurement -Diamond indentation Impact Tests measure? - correct answer ✔✔Toughness
-Specimen clamped horizontally -Broken by impact from pendulum released at specific height -Also known as Charpy V-notch test - correct answer ✔✔Charpy Test How do Impact Tests measure toughness? - correct answer ✔✔Energy absorbed during breakage is measure of materials toughness and yield strength -Specimen clamped vertically -Broken by impact from pendulum released at specific height - correct answer ✔✔Izod Test What is the purpose of a blast furnace - correct answer ✔✔To reduce iron oxides into molten ore Useful forms of iron - correct answer ✔✔Steel Cast iron First stage of blast furnace - correct answer ✔✔Ore is converted to pig iron Second stage of blast furnace - correct answer ✔✔Pig iron further refined to steel or cast iron What is pig iron - correct answer ✔✔Crude iron from smelting furnace Iron, coke and limestone are dumped into top of blast furnace, whats the purpose of each? - correct answer ✔✔Iron ore - iron Coke - fuel Limestone - combines with impurities to form slag Process length for raw materials in Blast furnace - correct answer ✔✔6-8hrs
How much limestone per tonne iron produced is used in Cupola furnace and what is the limestone used for? - correct answer ✔✔3-5kg Fluxing The addition of scrap steel/cast iron to pig iron in Cupola furnace does what to overall carbon content - correct answer ✔✔Lowers overall carbon content of cast iron How does grey cast iron get its colour - correct answer ✔✔fractures along graphite Produced by slowly cooling molten materials allowing carbon to dissociate and form graphite flakes within iron - correct answer ✔✔Grey Cast Iron Inexpensive Rigid Easily machined Withstands heat better than steel Withstands lubricated friction Strong under shear stress Weak under tension stress - correct answer ✔✔Grey Cast Iron Possesses carbon combined with iron Cooled rapidly in mold Hard material Difficult to machine Brittle Good wearing resistance - correct answer ✔✔White Cast Iron Another name for combined carbon - correct answer ✔✔cementite
Produced by giving white iron castings long heat treatment and annealing - correct answer ✔✔Malleable Cast Iron Heat treatment temperature to produce malleable cast iron - correct answer ✔✔ 925 °C Produced by adding magnesium or cerium High tensile strength Excellent machinability - correct answer ✔✔Ductile Iron Elements added to ductile iron do what to carbon? - correct answer ✔✔Cause carbon to precipitate as tiny spheres Alloy of iron and carbon - correct answer ✔✔Steel Steel has a carbon content of - correct answer ✔✔less than 2% Cast iron has a carbon content of - correct answer ✔✔more than 2% Carbon content in carbon steel - correct answer ✔✔less than 1% C content 0.05-0.3% Tough, ductile, easily formed - correct answer ✔✔Low carbon steel C content 0.3-0.45% Strong and hard Not easily welded - correct answer ✔✔Medium carbon steel What carbon percentage does welding become difficult - correct answer ✔✔0.35% C content 0.45-0.75%
Prevents brittleness at low temp More impact resistance Improve toughness 1-4% - correct answer ✔✔Nickel Resist oxidation by hot gases Maintain strength at high temp Increase response to heat treat. Hardness without brittleness 0.5-1.5% - correct answer ✔✔Chromium Alloy steel has what added to make stainless steel? How much? - correct answer ✔✔12% Chromium Decrease high temp creep Prevents temper embrittlement of chrome alloys Increased corrosion resistance 0.1-0.4% - correct answer ✔✔Molybdenum Fine grain structure during heat treatment Retards grain growth after periods extended heating Tools resist shock better 0.15-0.2% - correct answer ✔✔Vanadium Already contains other elements Improves atmospheric corrosion Increases yield strength 0.15-0.25% - correct answer ✔✔Copper Improves machinability
0.15-0.35% - correct answer ✔✔Lead Next in importance to carbon Deoxidizer Excellent wear/abrasion resistance Deformation causes surface hardening while internal remains ductile 0.5-2% - correct answer ✔✔Manganese Highest melting point of all metals Highest tensile strength Hardness close to a diamond Thermally/chemically stable 17-20% - correct answer ✔✔Tungsten Improves ultimate strength Reduced oxidation Improves electrical conductivity Increased fluidity Increased casting ability - correct answer ✔✔Silicon Failure that occurs below ultimate strength of a material due to repetitive stress and relaxation - correct answer ✔✔Fatigue Failure that occurs below ultimate strength of a material due to continuous load - correct answer ✔✔Creep Form internal structure of metal, crystal or grains - correct answer ✔✔Space lattice Mechanical work done at temps below recrystallization - correct answer ✔✔Cold working
Process which is charged with scrap iron, pig iron and ore - correct answer ✔✔Open- Hearth Process In an open-hearth process, as contents are melted whats happening to c content and whats the product - correct answer ✔✔c content reduced by oxidation carbon steel produced Molten iron combined with scrap iron and steel to produce steel is which process? - correct answer ✔✔Basic oxygen process What process? High pressure oxygen blown onto molten pool - correct answer ✔✔basic oxygen process In a basic oxygen process, what combustion temps are reached from oxygen reacting with pig iron - correct answer ✔✔ 2500 °C Advantages of basic oxygen process - correct answer ✔✔rapid operation lower cost ease of control Max amount carbon iron can hold - correct answer ✔✔6.67% Scrap is generally 100% of the charge - correct answer ✔✔Electric arc process Heat is created by electric current which arcs between graphite electrodes and scrap metal - correct answer ✔✔Electric arc process Electric arc process uses what to remove impurities - correct answer ✔✔pure oxygen Metals that don't have iron as their main component - correct answer ✔✔Non- ferrous Metals
Obtained from copper ore that is smelted and further refined by electrolysis - correct answer ✔✔copper What corrodes copper - correct answer ✔✔Ammonia Copper and zinc make - correct answer ✔✔Brass Copper and tin make - correct answer ✔✔Bronze Addition of 1% phosphorus in bronze makes... - correct answer ✔✔phosphorus bronzes bearing bronzes bronze may also contain _____ to improve machining ability - correct answer ✔✔zinc small amounts of lead, nickel, tin, aluminum and manganese may also be found in - correct answer ✔✔Brass 5-8% very corrosion resistant May include nickel, iron, silicon and manganese - correct answer ✔✔aluminum bronzes Readily shaped and welded into intricate patterns Often used for chemical process vessels - correct answer ✔✔silicon bronzes Produced from electrolysis from bauxite ore 1/3 as dense as iron or steel - correct answer ✔✔aluminum Alloy composed of lead and tin
Weakly bonded chains allowing slippage with sufficient thermal energy - correct answer ✔✔Thermoplastics Soft, pliable polymer - correct answer ✔✔Elastomer Chain orientations are random and not in continuous order Good impact strength/toughness - correct answer ✔✔Amorphous Chains in orderly, densely packed arrangement Closely resemble crystalline structures of metals - correct answer ✔✔Morphous Polymer with less flexibility than amorphous - correct answer ✔✔Morphous Solid non-metallic materials usually made by heating and cooling - correct answer ✔✔Ceramics Higher hardness and stiffness than metals and polymers - correct answer ✔✔Ceramics High performance ceramic materials contain.... - correct answer ✔✔oxides, nitrides and carbides of aluminum Composed of at least 2 substances working to produce needed specifications different from acting substances - correct answer ✔✔Composite material Continuous matrix with reinforcement of dispersed matrix to increase strength/stiffness of matrix - correct answer ✔✔Composite material Continuous matrix reinforcement usually in the form of.... - correct answer ✔✔long or short fibers, other particle forms also used Use metal like aluminum as matrix, reinforce it with fibers such as silicon carbide - correct answer ✔✔Metal Matrix Composites (MMC)
Use ceramic as matrix , reinforced with short fibers (whiskers) such as silicon carbide and silicon nitride - correct answer ✔✔Ceramic Matrix Composites (CMC) Also known as Fiber Reinforced Polymers (FRP) - correct answer ✔✔Polymer Matrix Composite (PMC) Use polymer based resin as matrix, reinforced by a variety of fibres such as glass, carbon, aramid(Kevlar) - correct answer ✔✔Polymer Matrix Composite (PMC) whiskers - correct answer ✔✔short fibre reinforcements Aramid is the generic name for an organic polymer known as - correct answer ✔✔Kevlar Most common man made composite - correct answer ✔✔Polymer Matrix Composite (PMC) Why are white metals are good thermal conductors - correct answer ✔✔to conduct heat away from bearing surface Best steel is produced from where? - correct answer ✔✔electric arc furnace Percentage of tungsten in steel tools - correct answer ✔✔17-20% Temper carbon - correct answer ✔✔carbon in form of rounded particles of graphite Ferrite - correct answer ✔✔pure iron with no carbon Some add to fuel efficiency of heat engines, and elimination of cooling systems - correct answer ✔✔Ceramic Matrix Composites (CMC)
