Laser beam welding of heat-resistant mixed joints using laser-based pre- and post-heating

Abstract Heat-resistant materials often have to be combined with cast materials if the requirements for temperature resistance differ within an assembly or if a resource-efficient and stress-oriented design is to be realized. However, unless additional filler wires are used, this leads to defects such as cold cracks, originating in carbon-related local hardening, and hot cracks, which are formed due to high nickel content. In order to avoid these defects, the influence of the mixture of the elements in the melt as well as the influence of heating and cooling rates of the seam and heat-affected zone is investigated. Metallographic analyses as well as static, dynamic and thermal tests are performed to evaluate the results. It has been shown that laser-based heat treatment can significantly improve weld seam quality and mechanical properties.