17) Lower critical temperature of high carbon steel while hardening is

Answer is:

723 Degree Centigrade

Explanation:

The lower critical temperature is same for all steels Lower critical temperature for steel’s austenite-to-pearlite transformation is 1333 ºF (723 ºCelsius). Below this temperature, austentite doesn’t exist.

Heat Treatment MCQ - Machinist(Set-1) with Answers

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Related Heat Treatment MCQ - Machinist(Set-1) with Answers

18) A approximate hardness of HSS milling cutter is

Answer is:

62 HRC

19) The purpose of heat treatment is

Answer is:

To change the mechanical properties of steel

20) One component of C50 steel is heated to 830 Degree Centigrade, soaked it for some time and then quenched in oil. Again it is heated to 600 Degree Centigrade and quenched in oil. Name this process of heat treatment.

Answer is:

Hardening and tempering

21) Which one of the following groups of quenching media is in order of their severity of the cooling rate, i.e. from slow to rapid cooling ?

Answer is:

forced air, oil, brine solution

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