1Material: DC53Hardness: 60-63HRC；2 Material :SKH51Hardness: 61-64HRC；3Material : HAP40 Hardness 64-67HRC all undergo the vacuum furnace heat treatment ,proper rotation of tempering technology .This material is superior to the SKD11 and SKD12 in the tenacity ,wearability and hardness under the high temperature .It can reduce the wear and tear a lot .Owing to the advanced technology the connection part's hardness between has been improved in great deal .