Application of laser beam welding to joining of continuous fibre reinforced composite to metal

Abstract

AbstractLaser beam welding was applied to the joining of SiC fibre reinforced Ti–6Al–4V composite to Ti–6Al–4V alloy. The weldability obtained for a wide bead (900 μm width) is superior to that for a narrow bead (400 μm width), the maximum joint strength of 991 MN m−2 being obtained at the optimum laser beam position for the wide bead. When the beam position was closer to the composite than the optimum range, the SiC fibres were damaged and segregation of carbon and silicon occurred near the damaged fibres. This caused a deterioration of joint strength. When the laser beam position was further from the composite than the optimum range, the joint strength was reduced by incomplete welding and/or formation of grain boundaries between the composite matrix and the Ti–6Al–4V plate. Heat treatment at 1173 K for 3·6 ks improved the joints that were welded using unfavourable laser beam positions. Therefore, heat treatment extended the range of suitable beam positions, thereby facilitating control of the laser bea...