Causes of Surface Spalling of G20Cr2Ni4A Steel Carburizing Cylindrical Roller

Analysis on surface spalling of G20Cr2Ni4A steel carburizing cylindrical roller was studied by optical microscopy, energy dispersion spectroscopy, micro hardness testing and macrograph. The results show that the surface hardness and strength decreased were due to the excessive residual austenite and pearlite in cylindrical roller surface after carburizing and quenching, and then the contact fatigue spalling appearing at the action of outside force, so the cooling capacity of quenching oil should be ensured and quenching transfer time should be shorten as far as possible. Cold treatment following quenching might be adopted to further reduce the content of residual austenite on workpiece surface.