Abstract:The microstructure, texture, and yield strength of an advanced heat-resistant alloy weldment made with composition-matched weld filler were investigated. Scanning electron microscopy, energy dispersive spectroscopy, and electron backscatter diffraction were used to characterize the microstructural and textural changes. Various grain boundary engineering (GBE) processes were performed on the weldment. The yield strengths of the weldment at 973 K were obtained before and after GBE processing, and were mostly consistent with the theoretically predicted values. The coincident-site lattices, misorientation, and recrystallization of the weld metal after GBE were analyzed, and the results indicate that the increase in dislocation density and the improvement in special grain boundaries in the weld metal are the main reasons for the yield strength elevation of the weldment after GBE. The variation in elongation after high-temperature tests has the same tendency as that in the impact toughness with different GBE parameters, which is related to the coarsening behavior of carbides.

Key words: grain boundary engineering; advanced Fe-Cr-Ni alloy; weld metal; yield strength