Laser gas assisted nitriding of Ti-6Al-₄v alloy and residual stress analysis

The stress field generated during laser gas assisted nitriding is considered and temperature and stress fields are predicted in the nitride layer using the finite element method. The residual stress in the resulting nitrided layer is measured using the X-ray diffraction technique and indentation tests. It is found that predictions of residual and measurements are in qualitative and quantitative agreement in the nitride layer. The magnitude of residual stress is in the order of 280 MPa in the surface region and reduces to 100 MPa at a depth of 80 μm where nitride layer diminishes.