Research on Heredity of Coarse Ferrite Grains

The changes in austenite grain size of the specimens with coarse ferrite grains under different heat treatment process were investigated. The focus was on studying the effect of annealing on refining coarse ferrite grains, as well as the influence of the ferrite grain size on the main technical indicators of gas carburizing. The results show that coarse ferrite grains may not necessarily cause the coarse austenite grains, but may result in mixed austenite grains. After annealing treatment, the coarse ferrite grains can be significantly refined and homogenized. Moreover, the coarse ferrite grains have no significant effects on hardness and intergranular oxidation of gas carburizing.