The conventional constant current arc welding of Hastelloy X (Ni-Cr-Fe-Mo) leads to the solidification and liquation cracks in the weldment. The higher heat supplied in constant current weldment develops the secondary carbide precipitates. It promotes the development of hot cracks in the weldment. In this study, joining of Hastelloy X plates was carried out by constant current gas tungsten arc welding (GTAW) and pulsed current gas tungsten arc welding (PCGTAW) with C263 filler wire. The result discovered that no hot cracks were formed in the weldment. In constant current mode, Cr-rich and Mo-rich Cr₂₃C₆ (M₂₃C₆), Fe₂MoC, Fe₃Mo₃C (M₆C), and Cr₂Ti precipitates were observed. Whereas, in pulsed current mode, Ni₃(Al, Ti), Ni₃Ti, Co₃Ti, Cr₂Ti precipitates are found due to the segregation of Co, Al, and Ti. No Cr-rich and Mo-rich carbide phases identified in pulsed current weldment due to rapid cooling rate and higher thermal gradient observed during solidification. The tensile results revealed that 8.23% increase in the ultimate tensile strength and a 29.62% increase in elongation of pulsed current mode welding compared to constant current welding. Further, the microhardness and impact toughness of PCGTAW is 3.32% and 5.45% higher than GTAW, respectively. In pulsed current welding, better mechanical properties were identified compared to constant current welding. The nonappearance of Cr and Mo-rich phases and refined microstructure in the weldment are the main reason for better strength.

哈氏合金X（Ni-Cr-Fe-Mo）的常规恒流电弧焊会导致焊件中的凝固和液化裂纹。恒定电流焊接中提供的较高热量会产生二次碳化物沉淀。它促进了焊件中热裂纹的发展。在这项研究中，Hastelloy X板的焊接是通过采用C263填充焊丝的恒流气体钨极电弧焊（GTAW）和脉冲电流气体钨极电弧焊（PCGTAW）进行的。结果发现在焊件中没有形成热裂纹。在恒定电流模式下，富Cr和富Mo的Cr ₂₃ C ₆（M ₂₃ C ₆），Fe ₂ MoC，Fe ₃ Mo ₃ C（M ₆C），观察到Cr ₂ Ti沉淀。而在脉冲电流模式下，Ni ₃（Al，Ti），Ni ₃ Ti，Co ₃ Ti，Cr ₂由于Co，Al和Ti的偏析，发现有Ti沉淀。由于凝固过程中观察到的快速冷却速率和较高的热梯度，在脉冲电流焊件中未发现富铬和富钼的碳化物相。拉伸结果表明，与恒定电流焊接相比，脉冲电流模式焊接的极限抗拉强度提高了8.23％，延伸率提高了29.62％。此外，PCGTAW的显微硬度和冲击韧性分别比GTAW高3.32％和5.45％。在脉冲电流焊接中，与恒定电流焊接相比，具有更好的机械性能。焊件中不出现富含Cr和Mo的相以及微细的组织是提高强度的主要原因。