The impact of aging pre-treatment on the hot deformation behavior of alloy 800H at 750 °C

The influence of aging pre-treatment on the hot deformation of a commercial alloy 800H was investigated through uniaxial compression tests. Aging pre-treatments were performed at 750 °C for 0 h, 5 h, 10 h, 20 h and 50 h, followed by compression tests at 750 °C with strain rates of 0.01 s−1, 0.1 s-1 and 1 s−1. The flow curves signified that the peak stress decreased evidently with increasing aging time. The microstructural analysis of alloy 800H after aging at 750 °C for 50 h indicated that the predominant precipitates are block-shaped Cr23C6 and cube-shaped Ti(C,N). The formation of grain-boundary Cr23C6 results in the segregation of Cr and C with the depletion of Ni at the grain boundaries. The kernel average misorientation maps after hot deformation demonstrates that the grain-boundary precipitates induce the pinning force to change the distribution of local misorientation and two different deformation patterns were defined to characterize the substructure developed near the grain boundaries.