Notched Tensile Fracture of Ti-6Al-6V-2Sn Laser Welds at Elevated Temperatures

Abstract

The notched tensile tests of Ti-6Al-6V-2Sn laser welds with distinct post-weld heat treatments (PWHTs) were carried out at 150, 300, and 450oC and the results were also compared with the mill-annealed base metal (BM). The BM specimen had the highest notched tensile strength (NTS) among the specimens being tested at room temperature but became the lowest at 450oC. At/above 150oC, all welds showed a decrease in NTS with increasing temperature. The cracks tended to grow along the α / β interface in the BM specimen. The formation of premature fine pores at the grain boundary in the weld with PWHT at 704oC accounted for the intergranular dimple fracture of the specimen. The fracture appearance of the as-welded (AW) and the 482oC-aged (W-482) welds comprised of mainly transgranular dimple and increased the extent of grain boundary shear at elevated temperature