The microstructure of ERNiCrFe-13 multipass weld metal has been shown to contain Laves/γ or σ/γ eutectic constituents that can increase susceptibility to solidification and weld metal liquation cracking resulting from the low eutectic reaction temperature. Under poor heat dissipation conditions such as on the edge of large thickness welded components, a partially melted zone (PMZ) may form in the weld metal during multipass welding. The microstructural evolution and liquation cracking susceptibility of this PMZ in ERNiCrFe-13 multipass welds have received little attention. In the present study, a tungsten inert gas (TIG) refusion process is used to simulate a thermal cycle with a long elevated temperature dwell time in order to investigate the microstructural evolution and liquation cracking in the weld metal PMZ. The results show that the eutectic microstructures in the PMZ evolve into three eutectic morphologies after TIG refusion, including long linear chains extending perpendicular to the boundary between the refusion zone and PMZ, skeletal structures, and fine lamellar networks. This evolution contributes to constitutional liquation occurring at the γ/Laves and γ/σ interface. Nb and Mo play a leading role in the constitutional liquation of γ/Laves and γ/σ eutectic microstructures, respectively. Liquation cracking in the PMZ is shown to occur along the linear chain grain boundaries resulting from constitutional liquation.

ERNiCrFe-13多道次焊接金属的微观结构已显示出包含Laves /γ或σ/γ共晶成分，这些成分可增加由于低共晶反应温度而导致的凝固和焊缝金属液化裂纹敏感性。在较差的散热条件下，例如在大厚度焊接部件的边缘上，在多道次焊接过程中，焊接金属中可能会形成部分熔化的区域（PMZ）。ERNiCrFe-13多道次焊缝中这种PMZ的组织演变和液化开裂敏感性很少受到关注。在本研究中，使用钨极惰性气体（TIG）回流工艺来模拟高温停留时间较长的热循环，以研究焊缝金属PMZ中的组织演变和液化裂纹。结果表明，TIG熔覆后，PMZ中的共晶组织演变为三种共晶形态，包括垂直于熔覆区和PMZ之间边界延伸的长线性链，骨架结构和精细的层状网络。这种演变有助于在γ/ Laves和γ/σ界面处发生结构液化。Nb和Mo分别在γ/ Laves和γ/σ共晶组织的液化中起主导作用。PMZ中的液化裂纹显示为沿着由组成性液化引起的线性链晶界发生。和精细的层状网络。这种演变有助于在γ/ Laves和γ/σ界面处发生结构液化。Nb和Mo分别在γ/ Laves和γ/σ共晶组织的液化中起主导作用。PMZ中的液化裂纹显示为沿着由组成性液化引起的线性链晶界发生。和精细的层状网络。这种演变有助于在γ/ Laves和γ/σ界面处发生结构液化。Nb和Mo分别在γ/ Laves和γ/σ共晶组织的液化中起主导作用。PMZ中的液化裂纹显示为沿着由组成性液化引起的线性链晶界发生。