Experimental Study on the Influence of Surface Carbon Content on Crack Initiation for 20Cr2Ni4A Steel

20Cr2Ni4A20Cr2Ni4A steel is a kind of low-carbon steel mainly used in manufacturing heavy-duty transmission gears. The carburizing and quenching process is a common strengthening method for gears to get the fine mechanical properties. For the reason of quenching deformation, grinding is used to improve tooth surface accuracy, leading to uneven distribution of surface carbon concentration. In this paper, the different carburizing processes are applied for the 20Cr2Ni4A20Cr2Ni4A samples. Different surface carbon contentSurface carbon content is obtained by grinding with different depths. Three-point bending fatigue test is conducted to study the relationship between crack initiation and surface carbon concentration. The crack initiationCrack initiation and propagation process is monitored by industrial cameras and strain gauges. The number of cycles of crack initiationCrack initiation is positively correlated with the surface carbon content within the range of 1%. And the carbide particles are the main fatigue source.