①Material : DC53(equivalent to SKD11) Hardness : 60-63HRC②Material : SKH51 Hardness : 61-64HRC③Material : HAP40(SKH40) Hardness : 64-67HRC ,Vacuum furnace heat treatment and advanced tempering technology enable the DC53 (EQUIVALENT TO SKD11 ) has better properties in toughness, grind-resistance and hardness at high temperature compared to SKD11 and SKD12. The strength at the joint part of shoulder and pin has been significantly increased.