Residual stress and cohesive strength of TiC composite coating on aluminum alloys during laser surface engineering

Changes in processing parameters strongly affect the structure and properties of laser processed coatings and consequently, their performance. In this present study, residual stress and cohesive strength of laser surface engineered titanium carbide (TiC) coating on 2024 and 6061 Al alloys were studied as a function of the varying laser traverse speed. The cohesive strengths and residual stresses are measured by four-point bend test and the XRD "sin2w " technique, respectively. The results showed that the residual stresses have a significant effect on the cohesive strength and microstructure of the coatings. The magnitude of residual stresses changed from more compressive to less compressive with increasing laser traverse speed, consequently changing the values of the coatings from higher strengths to lower. These changes are explained by the varying cooling rates and the energy inputs within the coatings at different laser traverse speeds. Microstructural characterization evidenced delamination of the coating at higher traverse speeds whereas a strong bonding at lower traverse speeds, thus demonstrating the effect of the processing conditions on the performance of the coating. This study is essentially aimed at optimizing the processing parameters to manufacture coatings with a desired performance.