Constitutive behavior and processing maps of low-expansion GH909 superalloy

Abstract

The hot deformation behavior of GH909 superalloy has been studied systematically using isothermal hot compression tests in temperature range of 960-1040°C at strain rates of 0.02-10 s −1 with height reduction up to 70%. The relations considering flow stress, temperature, and strain rate have been evaluated via power-law, hyperbolic sine, and exponential constitutive equations in different strains conditions, and exponential equation is first found more appropriate for process modeling. The processing maps for the alloy were constructed at the strains of 0.2, 0.4, 0.6, and 0.8 based on the dynamic material model, and a total processing map considering all the investigated strains was proposed. Metallurgical instabilities in the instability domain mainly located at higher strain rates were manifested in the form of adiabatic shear bands and cracking. The stability domain occurred at 960-1040°C and strain rates less than 0.2 s −1 , and it is recommended for optimum hot working conditions of GH909 superalloy.

The hot deformation behaviors and constitutive modeling of Hastelloy C276

“…Lypchanskyi et al [41] identified the undesirable and potentially favorable thermal deformation parameters of Nickel-Based Superalloy. Yao et al [42] created the processing maps of the GH909 superalloy. Chen et al [43] constructed a processing map of GH4698 alloy at high-temperature deformation conditions.…”