Effect of TiN Spray Coating on Cracking Susceptibility and Energy Absorption in Laser Welding of Aluminum Alloys

This paper reports on the effect of a TiN spray coating on aluminum to improve laser welding issues such as cracking susceptibility and laser absorption. A self-restraint hot cracking test and bead on plate test were employed to compare the laser weldability between the base material and TiN-coated material. The welds with the TiN coating can be fully penetrated without cracks at lower power than the welds without the coating. TiN-incorporated metal matrix composites were formed on the top layer irradiated with the laser. The layer increases the laser absorption to transfer energy efficiently and strengthens it to withstand higher stresses and strains. In addition, the welding mechanism of this process is such that the ceramic coating layer blocks direct interaction between the laser and the metal melting pool, so that a keyhole is not formed, and welding is performed by heat conduction through the TiN ceramic medium.