Calculating the stress of multi-track formations in induction-assisted laser cladding

In laser cladding weld bead tracks, which are often made of wear and corrosion resistant materials, are strongly joined to the subjacent work piece forming surfaces as well as complex volume build-ups. The process is typically characterized by high laser-related temperature gradients and also density changes due to phase transformations arising during cooling. That results in high thermal stresses which even may lead to the formation of cracks in case of brittle materials. An optimized temperature distribution of the process zone which might be reached by optimized process conditions or by additional inductive heat sources can significantly reduce critical stresses and, hence, the danger of cracking. Additionally the stress formation can be strongly influenced by a suitable placement of neighboring weld beads. Stresses of multi-track formations are completely different compared to the stress distribution of a single weld bead. By means of a heuristic as well as a three-dimensional FEM-model the interaction between process parameters, tailored temperature distributions and the placement of tracks has been clarified. Especially the transition of metallographic cross-sections into numerical meshes enables realistic simulations close to experiments. By means of parameter variations, stress levels can be reduced and the use of harder coating materials becomes possible