Identification of optimal deforming parameters from a large range of strain, strain rate and temperature for 3Cr20Ni10W2 heat-resistant alloy

Abstract

The intrinsic workability of 3Cr20Ni10W2 was investigated using processing maps constructed from the stress–strain data generated by isothermal compression tests with a height reduction of 60% over a temperature range of 1203–1403K and a strain rate range of 0.01–10s−1. As the true strain was −0.3, −0.5, −0.7 and −0.9, the responses of strain rate sensitivity (m-value), power dissipation efficiency (η-value) and instability parameter (ξ-value) to temperatures and strain rates were evaluated respectively. By the superimposition of power dissipation and instability maps, the stable regions with higher power dissipation efficiency (⩾0.3) and unstable regions were clarified clearly. As the true strain was −0.3, −0.5, −0.7 and −0.9, respectively, the area of instability regions decreased with increasing true strain from −0.3 to −0.7, while it increased with increasing true strain from −0.7 to −0.9. In further, in the stable area, on the basis of determination for domains with dynamic recrystallization (DRX) microstructural evolution, the DRX-predominant regions with higher power dissipation efficiency were identified and recommended. Then not only DRX-predominant domains were validated by the stable microstructures refined by DRX, but also the regimes of flow instabilities were validated by the microstructures involving cracks. The identification of optimal deforming parameters from a large range of strain, strain rate and temperature for 3Cr20Ni10W2 heat-resistant alloy contributes to designing reasonable hot deforming processes without resorting to expensive and time-consuming trial-and-error methods.