34) The process of producing a component with tough and ductile core and a hard outer surface is known as

35) The process of heating steel to about 40 Degree Centigrade above the upper critical temperature and cooling it in still air to room temperature is known as

36) Which one of the following heat treatment processes produces a scale-free surface on the component ?

37) In heat treatment process annealing is done to

38) After hardening process, the metal becomes more hardened and also will become more