Effect of Stress Relief Heat Treatment on Properties of 10CrNi4MoV Steel

The mechanism of decrease in impact toughness of10CrNi4MoV steel subjected to stress relief heat treatment has been investigated．It is reavealed that the discrimination of phosphorus and carbon induced by stress at grain boundary results in the weakness of grain boundary．Tear fractures and ductile intergranular fractures,and consequently are contributing factor to the decrease of the impact toughness of the plate．