某LC65-2205双相不锈钢焊管在热弯成形后进行低温冲击试验，发现弯管焊缝的冲击性能严重降低。采用金相检验、断口分析、热处理工艺验证等方法，研究了热弯成形对弯管焊缝低温冲击性能的影响。结果表明：焊管热弯成形过程中冷却速度较慢导致大量σ相析出，使位错滑移受阻，大量位错聚集在弯管焊缝并造成应力集中，最终导致焊缝的低温冲击性能显著下降。

Low temperature impact test was carried out on a LC65-2205 duplex stainless steel welded pipe after hot bending forming. It was found that the impact property of elbow weld seam was seriously reduced. The effect of hot bending forming on low temperature impact property of elbow weld seam was studied by means of metallographic examination, fracture analysis and heat treatment process verification. The results show that the slow cooling rate during hot bending of welded pipe resulted in a large amount of σ phase precipitation, which hindered dislocation slip. A large number of dislocations accumulated in the elbow weld and caused stress concentration, which ultimately led to a significant decrease in impact property of the weld under low temperature.