Abstract
Keywords
Dissimilar friction welding, Weld interface, Crack length, Fatigue life, Stainless steel
Abstract
Due to economical and technical advantages in friction welding application, heat-resisting and anti-corrosive materials are widely used in the industrial production fields of the mechanical components such as gas turbines, engines, nuclear power plants, automobile industry, and so on. The objective of this paper is to study fatigue characteristics on dissimilar friction welding zone according to defect positions. In order to achieve the objective, dissimilar steels commonly used as valve materials for vehicle were friction-welded. And a small circular defect was precisely worked on weld interface, 0.5 mm and 1.0 mm distance away from the interface respectively to closely analyze the welding zone.
Fatigue limits of STR3 and STR35 base metal were 429.0MPa and 409.4MPa respectively. In comparison with fatigue lives on the basis of the same defect positions, fatigue life of the STR35 was about 190% for base metal specimen, about 82% for 1.0mm HAZ specimen. It was higher than that of the STR3. But in case of 0.5mm defect position, the STR35 showed about 35% lower fatigue life than that of STR3. And the fatigue life of STR3 was about 99% for 1.0mm HAZ and 640% for 0.5mm HAZ. It was higher than that of base metal. And fatigue life of STR35 was about 25% for 1.0mm HAZ and 82% for 0.5mm HAZ. It indicates that the nearer weld interface, the higher fatigue life. But the weld interface notched specimen had much lower fatigue life than the other specimens because of appearance of the interface separation.