Fabrication of diffusion bonding of an ODS Ni-Base alloy; MA758 and the evaluation of high temperature fatigue strength

摘要

Diffusion bonding of an oxide dispersion strengthened (ODS) Ni-base alloy, MA 758, was studied by combining several bonding parameters: bonding temperature, bonding pressure, surface finishing, base material produced by different thermo-mechanical heat treatments, orientation of the base material, and the post weld heat treatment for secondary recrystallization. The optimum bonding condition was filtered and refined on the basis of the continuous grain growth structure across the welded interface,the size and the number of defects, the hardness distribution, and the mechanical properties of the joints. The fatigue strength of the joints thus optimized was also evaluated at high temperature in air, and was compared with that of the base material.