Numerical analysis of multi-layered laser cladding for die repair applications to determine residual stresses and hardness

Abstract

Laser cladding provides numerous advantages over the traditional, ad-hoc and imprecise deposition techniques for the repair of critical structural components such as dies and molds used in cold working industries. A necessity of a good quality laser cladding is to offer durable and reliable adhesion to the substrate with reduced dilution and absence of pores, cracks, and delamination. The process can add to complications due to addition of the second layer on the surface of the first clad layer that can generate local variation in shrinkage, layers of additive material are added onto the non-planar domain and the additional distance from the substrate. Consequently, residual stresses previously induced in a first clad layer and substrate region can alter. Largely, tensile residual stresses in the clad layer or clad-substrate interface region can lead to accelerated fatigue failure. Prediction and mitigation of tensile residual stresses still remain important issues in multi-layer laser cladding. Finite element modelling is an appropriate way to estimate the residual stress profile and microstructural changes for the prediction of optimal process parameters. The current work focuses on the development of a coupled metallo-thermomechanical finite element model in ABAQUS\® for multi-layered laser cladding of CPM9V powder on H13 tool steel. The residual stress evolution along the cross-section has been characterized at different process conditions and the optimal conditions corresponding to mitigation of tensile residual stresses have been identified. The hardness can be affected due to the deposition of an additional layer and tempering can occur in clad or substrate which needs to be understood. The micro-hardness values are estimated using the numerical model and compared with the measured data using a Vickers hardness tester. It has been observed that the peak magnitude of tensile residual stress in the clad region with multiple layers is lower than the peak residual stresses in single layer clad of the same height along with the hardness.