Vacuum Carburizing of a Dual Phase Steel

A dual phase steel has been developed for which grain refining treatment subsequent to vacuum carburizing treatment at high temperature above 1000°C is not necessary. This 2wt% Si steel, which contains 0.3 wt% V and 0.04 wt% Nb, has a fine structure in both the core and case, sufficient surface hardness and excellent mechanical properties equivalent to those of SCr 420 steel, even without grain refining treatment subsequent to vacuum carburizing at 1050°C.