Question

In the process of hardening of steel, the metal has to be heated to a temperature ______ the critical range.

(a) below

(b) half

(c) above

(d) around

I got this question in examination.

The doubt is from Heat Treatment Terms topic in chapter Physical Test & Heat Treatment Terms of Aerospace Materials & Processes

Answer 1

Correct choice is (c) above

The explanation: In the process of hardening of steel, the metal has to be heated to a temperature above the critical range. Hardening increases the strength of the material. In order to alter the internal atomic structure of the steel to change its properties, heating it above the critical range is required.