The effect of laser cladding on rail failure: Measurement of residual stresses and response to cyclic loading

Laser cladding is an additive manufacturing method for producing functionally graded materials by coating a metallic substrate with an alloy possessing superior properties. In order to prevent fracture due to the wheel-rail contact, it is proposed to clad rail track components of high value with alloys of superior properties. With this in mind, it is critical to evaluate the residual stress state of the components after cladding and its subsequent response to cyclic loading. Two materials have been tested within this research; a cobalt-based alloy and a martensitic steel. The study has shown that high residual stresses are generated by laser cladding rail material, that they do not exhibit shakedown upon cyclic loading and that poor choice of laser cladding parameters can significantly reduce component lifetime.