Question

Which tempering process is used to increase the endurance and elastic limit of the material?

(a) Low-temperature tempering

(b) Medium temperature tempering

(c) High-temperature tempering

(d) Endurance limit cannot be increased

This question was addressed to me in a national level competition.

My query is from Tempering in chapter Heat Treatment of Engineering Material & Metallurgy

Answer 1

Correct answer is (b) Medium temperature tempering

To explain I would say: Medium temperature tempering is performed between 350^oC and 450^oC. This process develops a tempered-troostite structure and increases the endurance and elastic limits of the material.