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 degrees C for 0 h, 5 h, 10 h, 20 h and 50 h, followed by compression tests at 750 degrees 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 degrees 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. (C) 2014 Elsevier B. V. All rights reserved.