RESIDUAL STRESS MODELING OF POWDER INJECTION LASER SURFACE CLADDING FOR DIE REPAIR APPLICATIONS

Laser cladding is a technique in which a layer of material is deposited over a base material in order to improve its wear/corrosion resistance. It is also used as an additive manufacturing and repair technique. In the present work crucible steel CPM9V is deposited over H13 tool steel which could potentially be used for die repair purposes. CO2 laser is used to melt the powder which is deposited by powder injection technique. Note that the dies are exposed to cyclic thermo-mechanical loading and prone to fatigue. Consequently, major issues which needed to be analysed are residual stresses and the heat affected zone. The residual stresses are produced due to high thermal gradients and difference in values of coefficient of thermal expansions of clad and substrate. A three dimensional finite element model is developed to evaluate residual stresses incorporating conductive, convective and radiative heat transfer and assuming temperature dependent thermo-mechanical behaviour for both materials. Experimental analysis is performed using X-ray diffraction technique to evaluate residual stresses and the heat affected zone (HAZ) is characterized via optical microscopy. A comparison between the model predictions and the experimental results shows that model is able to capture the phenomena during the repair process.