Mechanical Engineering - Engineering Materials - Discussion

Discussion Forum : Engineering Materials - Section 6 (Q.No. 18)
18.
A steel is heated at about 875° C where the structure consists of entirely austenite. It is then cooled suddenly at a temperature of about 250° C to 525° C. This process of heat treatment is known as
normalising
annealing
austempering
martempering
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
1 comments Page 1 of 1.

Sandeepji said:   8 years ago
Austempering is a quenching technique. The part is not quenched through the Martensite transformation. Instead, the material is quenched above the temperature when Martensite forms MS, around 315° C (600° F). It is held till at this temperature till the entire part reaches this temperature. As the part is held longer at this temperature, the Austenite transforms into Bainite. Bainite is tough enough so that further tempering is not necessary, and the tendency to crack is severely reduced.
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