MATSUSHITA Muneo KITANI Yasushi IKEDA Rinsei
Applicability of friction stir welding (FSW) to steels was studied with respect to the tensile strength and thickness of base metal. Using the advanced high strength steel sheets with tensile strength grade between 590 and 1 180 N•mm−2 and thickness of 1.6 mm for automotive applications, the appropriate parameter windows for tested steels were investigated. The result showed that the higher the tensile strength of base metal was, the narrower the parameter window became. The investigation of weld joint properties verified that the tensile strength of weld joint was as high as that of the base metal up to 980 N•mm−2 grade. Using the structural steel plates with thickness of 12 mm and tensile strength grade of 400 N•mm−2, it was verified that the appropriate parameter existed to produce sound welds, and the investigation of mechanical properties of weld indicated that the toughness within the stir zone showed the variation, conceivably attributed to the inhomogeneous microstructure evolution.