Hot deformation behavior and physical-based constitutive modelling under plane-stress state for nickel-based superalloy sheets

Abstract

Forming limit curves (FLC) at high temperatures under plane-stress states are beneficial for guiding the process parameter design of hot forming superalloy sheets. Constrained by the high deformation temperatures, the establishment of FLCs of superalloy sheets at high temperatures is extremely difficult. This paper conducts an experimental and modelling research to establish the physical-based model with the accurate prediction of hot flow behavior as well as micro grain sizes, using which, the forming limit curves can be predicted. First, the uniaxial tensile tests under different temperatures and strain rates and electron backscattered scattering detection (EBSD) observations of typical conditions were conducted to obtain the hot flow behavior and grain evolution. Second, the dome test at room temperature was performed, and the corresponding simulation was further carried out to obtain the forming limit at room temperature under plane-stress states. Using the above results, a plane-stress constitutive model for GH3128 superalloy was established enabling plane-stress test results under typical hot conditions to be accurately predicted. The prediction accuracies of hot uniaxial and biaxial stretching results are 94.2% and 95.4%, respectively.