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本文结合Ｎｉ＿３Ａｌ基合金堆焊熔池凝固过程中的相变分析和堆焊层中的热应力分析，研究了电弧堆焊条件下Ｎｉ＿３Ａｌ基合金堆焊层中热裂纹产生的原因。分析表明，当电弧堆焊速度比较高时，由于堆焊熔池中液相快速冷却而发生非平衡相变，使所析出的富Ｎｉ枝晶γ相间的富Ａｌ液相最后发生共晶反应，而生成γ相和β′相片层组织。另外，高的堆焊速度使堆焊层中产生高的热应力。当堆焊层中局部热应力超过γ′相和β′相的内聚强度时，产生枝晶间开裂。若将电弧难焊工艺从沿直线堆焊变为沿‘Ｚ’形堆焊时，由于熔池中液相的冷却速度降低，使γ相枝晶间片层组织的生成受到抑制，同时使堆焊层中的热应力降低，从而阻止了Ｎｉ＿３Ａｌ基合金堆焊层的开裂
In this paper, the causes of hot cracks in the surfacing layer of Ni_3Al-based alloy under the condition of arc welding are studied in combination with the phase change analysis during the solidification of Ni_3Al-based weld pool and the thermal stress analysis of the overlay. The analysis shows that when the arc welding speed is relatively high, the non-equilibrium phase transformation occurs due to the rapid cooling of the liquid phase in the weld pool, resulting in the final eutectic reaction of the precipitated Al rich liquid phase between the Ni-rich dendritic γ phases. While generating γ-phase and β ’photo layer tissues. In addition, high build-up speeds create high thermal stresses in the overlay. When the local thermal stress in the overlay exceeds the cohesive strength of the γ ’and β’ phases, interdendritic cracking occurs. If the arc welding process from a straight line along the welding into a ’Z’ shaped surfacing, due to the cooling bath liquid phase cooling rate, so that dendrite intergranular lamellae formation is inhibited, while the reactor The thermal stress in the solder layer is reduced, thereby preventing the cracking of the Ni_3Al-based overlay