Laser localized coating of corrosion resistant metal over a steel weld bead

Coated steel sheet is one of the most important raw materials for the automotive industry. The commonly used Al or Zn based coatings on steel sheet provide a physical barrier and/or galvanic protection, and thus prevents a corrosive attack of the steel substrate. In order to make complex component or assembly, several steel sheets of various sizes, shapes, or thicknesses are welded together before or after being formed. Unfortunately, the process of welding together the precoated steel sheet pieces results in the formation of a weld joint that is devoid of anticorrosion protection. Re-formation of the protective coating over the weld joint could greatly improve the final product's quality in terms of resistance to corrosion. In this investigation, recoating of aluminum-silicon over laser weld joints has been explored by laser beam heating and powder injection. Precise coating over the weld joint was achieved. The produced coating on the welding bead is smooth when proper processing parameters are employed.