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16 Cards in this Set
- Front
- Back
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What are the 4 main types of heat treatment? |
Annealing Normalising Quenching Tempering |
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Why is heat treatment advantageous? |
Can change the microstructure at an atomic level through alloying and heat treatment. |
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What are the basic steps of heat treatment? |
Heating to a definite temperature, soaking, cooling at certain rate |
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What is involved in annealing? |
Heat to temperature
Soak steel at this temperature to allow desired change
Slowly furnace cool it for equilibrium phase transformation |
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What is the purpose of annealing? |
Soften steel - improve machinability Relieve internal stresses caused by rolling, forging, uneven cooling Remove coarseness of steels |
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What is normalising? |
Steel typically heated to 50°C above critical line. Soaked at temperature for certain time. Removed from furnace Cooled in air |
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What properties can be altered by normalising? |
Tensile strength, yield strength, reduction of area, impact value |
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What is quenching? |
Heating to a certain temperature. Cooling at rapid rate in water or oil. |
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What non-equilibrium phase is formed? Why? |
Martensite - All the carbon is locked in to solid solution |
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What is tempering? |
Heating the steel below the critical range to relieve stress and allow the arrested reaction of cementite precipitation. |
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What does tempering do to mechanical properties? |
Improves toughness without drastically reducing hardness and strength. |
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What are the 4 stages of tempering |
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What non equilibrium phase is a product of quenching? What does it look like? |
Bainite - needles and plates |
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What temps are upper and lower bainite formed? |
Upper bainite - 500°C to 350°C Lower bainite - 350°C |
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Look at this **** |
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And this |
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