Abstract: Induction hardening cracking of the inner gear ring of wind power was analyzed from the aspects of macro morphology, microstructure, decarburization layer and segregation. The analysis results show that carbon segregation and decarburization of forgings are important reasons for induction hardening cracking of the inner gear ring. When the carbon segregation degree of inner gear ring reaches above 0.04%, the risk of induction hardening cracking increases, and decarburization of tooth tip intensifies the risk of induction hardening cracking. The actual process improvement shows that the carbon segregation difference of the inner gear ring can be reduced to 0.02% by obtaining the blank with forging ratio greater than 7 by three-way forging, which can effectively avoid the carbon segregation. In the design of punching process, the segregation in the center of continuous casting slab can be eliminated by controlling the punching quality. When the blanking coefficient is greater than 0.019, the generation of micro defects and quenching cracks in the teeth can be avoided.

Key words: inner gear ring, induction quenching, cracking, segregation, decarburization