Residual Stresses in Steel Specimens Induced by Laser Cladding and their Effect on Fatigue Strength

Residual stresses resulting from circumferential laser cladding of fatigue test specimen of austenitic steel X5CrNi18-10 and heat treatable steel 42CrMo4 with Stellite 21 are evaluated by neutron diffraction. Below the interface of cladding and base material the former shows compressive residual stresses, the latter shows tensile residual stresses. Locations of crack initiation during fatigue testing correlate to the findings. Austenitic steel specimens crack at the surface whereas heat treatable steel components and specimens crack close to the interface. Fatigue strength of both material systems drops due to laser cladding whereby the drop of heat treatable steel is significant. It can be concluded that residual stress distribution needs to be optimized in order to conserve maximal fatigue strength.