Effect of Hot Bending Forming on Low Temperature Impact Property of Duplex Stainless Steel Elbow Weld Seam

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.