Estimation of residual stress and deformation of laser deposited tracks of Ni-5Mo-5Al powder using thermo-mechanical finite element simulation

Abstract

Exhaust fans and manifolds, valve and pump seats, connecting rods etc. are coated with Ni-5Mo-5Al powder for service temperature up to 650 °C. Till date, it has been coated on structural steels etc. substrate mostly using plasma spray and High-Velocity Oxy-Fuel (HVOF) spraying. However, a few pioneering works, reported cladding by melt and deposition of the same powder using laser. Laser being much more precise heat source has the potential to achieve cladding without causing much thermally induced damage. In this work, laser cladding of Ni-5Mo-5Al powder was simulated probably for the first time. Layer thickness and width were input from the experiments. A significant amount of tensile residual stress (up to 500 MPa normal stress component along the scan track) and deformation (up to 32 μm) of the deposited layer was found in the simulation results. These were more at higher laser power. Experiments consisted of depositing overlapping tracks, on AISI 1020 steel cylindrical substrates having 39 mm diameter and 22.4 mm thickness, by blown powder method, with the help of a 2 KW Yb fibre laser having 1.07 μmwavelength.