Investigations on correlation between grain size and stress rupture property of GH4169 alloy

Abstract

Taking GH4169 alloy large-size bar as research object, combined with the manufacturing process of the bar, the stress rupture properties of the specimens with different grain sizes were analyzed by means of OM, FE-SEM, EBSD and TEM. The results show that under the high temperature and stress of the long-lasting test, various grain size samples exhibit different stress rupture properties and grain orientation evolution. When the grain size is small, some orientation of〈101〉obviously rotates to 〈001〉or 〈111〉orientation where deformation and fracture occur. Besides, the coordination of macroscopic deformation of fine grain is better. These promote the effective release of stress concentration and then better plasticity. But the diffusion creep caused by more grain boundaries in the fine grain sample is unfavorable to the high temperature strength and cracks are prone to nucleate and expand at the grain boundary adjacent to the hard orientation of 〈111〉, thus the rupture life is reduced. In addition, the deformation of the fine grain sample is larger, mainly concentrated at grain boundaries, and the number fraction of large angle misorientation is more, which is easy to crack and reduce the life.

Keywords

• gh4169
• grain size
• stress rupture property
• grain orientation
• plastic deformation