Product Code: ICA12_504

Calculating the Stress of Multi-Track Formations in Induction-Assisted Laser Cladding
Authors:
Frank Brueckner, Fraunhofer IWS Dresden; Dresden Germany
Dietrich Lepski, Fraunhofer IWS Dresden; Dresden Germany
Steffen Nowotny, Fraunhofer IWS Dresden; Dresden Germany
Christoph Leyens, Fraunhofer IWS Dresden, Technische Univ. Dresden; Dresden Germany
Eckhard Beyer, Fraunhofer IWS Dresden, Technische Univ. Dresden; Dresden Germany
Presented at ICALEO 2012

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. This results in high thermal stresses which even may lead to the formation of cracks in the case of brittle materials.
An optimized temperature distribution of the process zone, which can be reached by means of 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. Hence, stresses of multi-track formations are completely different compared to the stress distribution of single weld beads. 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 such calculations including parameter variations, stress levels are reduced which permits the use of harder coating materials.