Hardening plain carbon steels a) What two factors does the hardness of a plain carbon steel depend..

Hardening plain carbon steels a) What two factors does the hardness of a plain carbon steel depend upon when through-hardening? b) Explain why steels have to be tempered after hardening and how the degree of temper is controlled when this is done over a brazing hearth in the workshop. c) When through-hardening, what is the effect of: i) overheating the steel ii) underheating the steel. d) When through hardening, explain how the hot metal should be quenched and what precautions must be taken to avoid cracking and distortion.