Characterization of Friction Stir Weldments in 500 Brinell Hardness Quenched and Tempered Steel

摘要

Friction stir welding (FSW) was successful in joining 6.4-mm and 12.7-mm (0.25 and 0.5-inch) plates of nominal 0.29C-Mn-Si-Mo-B 500 Brinell hardness steel using a polycrystalline cubic boron nitride (PCBN) tool material. The weldments were made without preheat and exhibited no apparent hydrogen-assisted cracking or distortion, and there was little evidence of tool wear in limited trials. Weldments were also made using gas-metal-arc welding (CMAW) for comparison. The transverse tensile strengths of the FS weldments were greater than those of conventional gas-metal-arc weldments, which were made using a lower carbon electrode. Charpy V-notch toughness of the FSW stir zone and heat-affected zone (HAZ) was similar to that of the plate material; the toughness of the GMA weld metal and heat-affected zone was generally higher. Microhardness varied across the weld region, and was lowest in the overtempered region of the HAZ in the FS welds and lowest in the weld metal in the GMA welds. Previous trials on high-strength low-alloy steels and the present trials on a high strength steel indicate that FSW technology is feasible for joining a variety of steels for structural applications.