Laser impact welding for joining similar and dissimilar metal combinations with various target configurations

Brittle intermetallics are easily formed during welding of dissimilar metals in many alloy system such as Al-Ti, Al-Fe, and Ti-Ni, usually resulting in poor mechanical performance. In this study, laser impact welding (LIW) was applied for joining of Ni-Ni, Al-Cu, Al-Ni and Al-Ti similar and dissimilar metal combinations. A series of experiments were conducted using a 3-Joule pulsed laser to study the influence of LIW parameters on the launch of the flyer component as well as the bonding between the flyer and target. Metallurgical bonds between Ni-Ni, Al-Cu, Al-Ni and Al-Ti combinations were successfully produced. A characteristic wavy interface was observed in all LIW samples. The impact angle plays a key role in the bonding between the flyer and target. The bonding area was significantly increased (up to 30 % of the impact region) when an appropriate impact angle was applied (nominally 7.5 degrees). In addition, Photon Doppler Velocimetry (PDV) was used to measure the impact velocity of the flyer during the LIW process. The full velocity of the flyer (over 400 m/sec) can be achieved within 1.1 μs. The impact velocity of the flyer was maintained at almost the same velocity even at relatively large standoff distance (32.5 mm). However, severe deformation of the flyer occurred when the displacement exceeded 3.0 mm.