Effect of Deformation Strengthening Process on Quality of Hardened Layer of Nimonic 80A Nickel Base Alloy Exhaust Valve

The effects of rolling temperature and deformation on the quality of hardened layer in the warm rolling strengthening process of conical surface of Nimonic 80A nickel base alloy exhaust valve disc were studied. The results show that under the same conditions, when the rolling temperature gradually increases from 655 ℃ to 715 ℃, the depth of the hardened layer with the hardness above 450 HV5 gradually increases, and when the rolling temperature exceeds 715 ℃, the depth of the hardened layer with the hardness above 450 HV5 gradually decreases. When the rolling temperature is 715 ℃, the hardness value at 2.7 mm away from the rolling surface is highest.