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Short answers

Short answers

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1. What is heat treating?

Heat treating is and an industrial process involving metal work that is used of alter

physical and chemical of a material.

2. What is mechanical properties are usually controlled in heat treating process?

Ductility, hardness, yield strength, tensile strength, and impact resistance.

3. What is meant by “processing heat treatment”

Processing heat treatment refers to different ways of heat treatment which include

annealing and hardening.

4. Define term critical temperature

Critical temperature is the temperature at and above which vapor of the substance cannot

be liquefied, no matter how much pressure is applied.

5. Which structure of metals is hardest and most brittle?

Cementite

6. List different types of quench media.

Water, brine (salt water), use of oil, and air

7. Which quench media cools the fastest? The slowest?

Oil quench media is the slowest.

Water quench media is the fastest.

8. What problems are associated with the use of oils for quenching?

i. Use of oil for quenching causes water contamination

ii. Use of oil for quenching causes smoke and fire hazards

iii. oil for quenching is expensive

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9. What are the three stages of hardening for through hardening processes?

i. Heating- heating the metal to a high temperature and then applying high heat

intensity.

ii. Cooling in water to reduce the temperature.

iii. Tempering (re-heating the metal )

iv. Cooling

10. What is tempering?

Tempering is a heat treatment process applied to metals to reduce brittleness.

11. An iron carbon phase diagram gives what information?

Formation of carbon steels and alloy steels

12. In differential heat treatment for surface hardening there are two main processes, flame

hardening and induction hardening. Describe each process.

i. Flame hardening

Flame hardening in its simplest form is the heating up of steel to its hardening

temperature by a flame and then quenching in water or oil. The gas used for the

heating is a mixture of oxygen and usually acetylene although occasionally

propane is employed. The gases are mixed in a burner unit whose shape is

dictated by the part to be flame hardened.

ii. Induction hardening

Induction hardening is a form of heat treatment in which a metal part is heated

by induction heating and then quenched. The quenched metal undergoes

a martensitic transformation, increasing the hardness and brittleness of the part.

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Short Answer Items Answers 1. What is heat treating? Heat treating is and an industrial process involving metal work that is used of alter physical and chemical of a material. 2. What is mechanical properties are usually controlled in heat treating process? Ductility, hardness, yield strength, tensile strength, and impact resistance. 3. What is meant by “processing heat treatment” Processing heat treatment refers to different ways of heat treatment which include annealing and hardening. 4. Define term critical temperature Critical temperature is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied. 5. Which structure of metals is hardest and most brittle? Cementite 6. List different types of quench media. Water, brine (salt water), use of oil, and air 7. Which quench media cools the fastest? The slowest? Oil quench media is the slowest. Water quench media is the fastest. 8. What problems are associated with the use of oils for quenching? i. Use of oil for quenching causes water contamination ii. Use of oil for quenching causes smoke and fire hazards iii. oil for quenching is expensive 9. What are the three stages of hardening for through hardening processes? i. Heating- heating the metal to a high temperature and then applying high heat intensity. ii. Cooling in water to reduce the temperature. iii. Tempering (re-heating the metal ) iv. Cooling 10. What is tempering? Tempering is a heat treatm ...
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