1999 Volume 85 Issue 1 Pages 66-70
Tensile tests and fatigue tests have been conducted for laser butt welded joints obtained from the combination of two steels and two plate thicknesses. Tensile and fatigue strengths were evaluated and the effects of type of steels and plate thickness on those strengths were studied on the basis of changes in microstructure, hardness and residual stress. Tensile strength of the joints with the same thickness was lower than that of the joints with different thicknesses and the joints of the same steel showed lower tensile strength than the joints of different steels. All joints were fractured at the location away from the center of the weld zone. Fatigue strength of the joints decreased compared with that of the base metal. The type of steels had no influence on the fatigue strength, while the fatigue strength of the joints were slighlty affected by plate thickness. In the joints with the same thickness, fatigue fracture took place at the location 4 mm to 5 mm away from the center of the weld zone, but in the joints with different thicknesses, at the shoulder between thin and thick plates, i.e. at the weld zone.
