Laser welding of refractory metals

Abstract

Welding of thick section refractory metals is difficult with conventional arc processes but can be accommodated with high intensity beam sources such as the electron or laser beam. High laser beam irradiance is necessary to achieve deep penetration of refractory metals with their high melting points. Consequently, a focused beam of high power and beam quality is required. A 500W diode pumped Nd:YAG was used to perform bead-on-plate tests on 2mm sheets of rhenium and tungsten. The welds were sectioned and analyzed for profile and porosity. Results indicate the difficulty in using high irradiance beams to weld rhenium and tungsten. Micro-hardness measurements indicate no significant decrease in hardness in the fusion zone. However, the presence of cracks tended to produce a slight decrease in the hardness measurements.Welding of thick section refractory metals is difficult with conventional arc processes but can be accommodated with high intensity beam sources such as the electron or laser beam. High laser beam irradiance is necessary to achieve deep penetration of refractory metals with their high melting points. Consequently, a focused beam of high power and beam quality is required. A 500W diode pumped Nd:YAG was used to perform bead-on-plate tests on 2mm sheets of rhenium and tungsten. The welds were sectioned and analyzed for profile and porosity. Results indicate the difficulty in using high irradiance beams to weld rhenium and tungsten. Micro-hardness measurements indicate no significant decrease in hardness in the fusion zone. However, the presence of cracks tended to produce a slight decrease in the hardness measurements.