Residual stresses in Co-based laser claddings investigated by lab X-rays and synchrotron diffraction techniques

It is a well known fact that cracking related problems may occur during the laser cladding deposition process. In particular for the improvement of thick coatings it is of prime interest to know how processing parameters affect the residual stress state. The residual strains developed in Co-based thick clad layers were investigated by laboratory Cu-K alpha and Synchrotron X-rays. On the surface the strain tensor is determined by the Sin(2)psi technique. Strain mapping performed by synchrotron radiation shows that tensile stresses dominate the upper region but may change into compressive towards the inner part of the coating. The effect of laser overlap is discussed and a mechanism for stress concentration is proposed.