Hot working behavior of hot-extruded Ni-Co-Cr-based powder metallurgy superalloy

Abstract

Isothermal compression tests were carried out on a Gleeble-3500D thermal simulation machine. The hot compression deformation behavior of a new hot-extruded Ni-Co-Cr-based powder metallurgy(P/M) superalloy at the temperatures from 1020℃ to 1110℃ with the strain rates from 10-3 s-1 to 1 s-1was systematically investigated. The flow stress curves were corrected by friction. Using the friction-corrected data, the constitutive equation for hot compression of the alloy and the flow stress model considering the strain compensation were established, respectively. At the same time, the hot processing map was built, and the hot deformation parameters of the alloy were optimized by combining with the analysis of the microstructure. The results show that apparently dynamic recrystallization occurs in the process of hot compression of the alloy, and the flow stress decreases with the decrease of strain rate or the increase of deformation temperature. The predicted values obtained from the developed flow stress model considering the strain compensation agree well with the experimentally friction-corrected data. According to the hot processing map and microstructural analysis, the reasonable hot working parameters of the alloy were suggested to be at the deformation temperatures of about 1076-1103℃ and the strain rates of about 10-3-10-2.77s-1.

Keywords

• nickel-based p/m superalloy
• hot compression deformation
• constitutive equation
• strain com-pensation
• hot processing map