Induction Hardening is a type of surface hardening in which a metal part is induction heated and then quenched. For engine valves this process can be done both for the tip of the valve and the seat area of the valve. This process can only be applied to Martensite Steels used for Engine valve manufacturing. The tip or Seat area of the valve is induction heated then quenched in special quenching oil in order to obtain the desired hardness value.