R. Dehmolaei - Department of Materials Engineering, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Iran
M. Shamanian - Department of Materials Engineering, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Iran
A. Kermanpur - Department of Materials Engineering, Isfahan University of Technology, Isfahan ۸۴۱۵۶-۸۳۱۱۱, Iran

The microstructure of HP stainless steel in aged and aged + solution annealed conditions and solutionized alloy ۸۰۰ was characterized by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) equipped by EDS. All phases present in the above condition were described. The effects of solution annealing heat treatment temperature on the microstructure, tensile, hardness, toughness, and ductility of aged HP stainless steel and its weldability to alloy ۸۰۰ have been discussed. In addition, the effects of heat input, interpass temperature, and type of filler metal on weldability of two alloys were investigated. It was found that during solution annealing, the precipitates produced in the aging stage are decomposed and niobium carbide (NbC) is formed. It was also observed that while tensile strength and hardness fell, ductility and toughness were improved. Dissimilar welding between alloy ۸۰۰ and aged HP stainless steel was not successful and cracks were observed in the HAZ of the aged HP stainless steel, while welding alloy ۸۰۰ to HP stainless steel (aged + solution annealing at ۱۱۰۰-۱۲۰۰ºC, low interpass temperature, and Inconel ۸۲ or ۶۱۷ filler metals) was successful.

Dissimilar Welding, Weldability, Solution annealing, HP steel, Alloy ۸۰۰