Analysis on Quenching Cracks on Carburized Surface of Products Made by 20CrNiMo Steel

The products made by 20CrNiMo steel were found cracked on the surface of carburizing area after quenching. Through a series of testing methods including chemical composition analysis, hardness testing and metallographic examination, the cracking cause was analyzed. The results showed that the quenching cracks existed only in the carburized layer. The main causes of quenching cracks on the surface were high carbon content, massive blocky and reticulate carbides in surface carburized layer.