Effect of long-term thermal exposure on microstructure of laser-welded UNS N10003 alloy

Abstract: The evolution of the microstructure and tensile rupture mechanism of laser welds in UNS N10003 alloy exposed to 700 ◦C are investigated. Fine M6C carbides precipitate around the primary eutectic M6C-γ carbides in the fusion zone after 100 h of exposure. During long-term thermal exposure, the size of the fine M6C carbides increased. The eutectic M6C-γ carbides in the as-welded fusion zone transformed into spherical M6C carbides as the exposure time extends to 10 000 h. Additionally, the spherical M6C particles exhibit size coarsening with increasing exposure time. The tensile properties of the welded joints are not adversely affected by the evolution of eutectic M6C-γ carbides and the coarsening of M6C carbides.