The influence of welding speed on friction stir welded of duplex stainless steel

Friction stir welding of 4 mm thick 2205 duplex stainless steel was carried out. When the welding speed is low, the well-formed joint without defects can be obtained. When the welding speed is reach 70 mm/min, the hole defect occurs in the bottom of the joint. After recrystallization, fine equiaxed crystals are formed in the stirred zone. The ferrite content in the whole joint is in the range of 48 to 60%, and the ferrite content in the stirred zone decreases with the increase of welding speed. With the increase of welding speed, the hardness and tensile strength of the stirred zone increase. When the welding speed is 50 mm/min, the joint performance reaches the optimal level. The tensile strength is 824 MPa, 97.3% of the base material. (paper)