Effect of preheating temperature on the macroscopic and microscopic residual stresses in laser-processed bronze matrix composite surface deposits

In industrialized nations, wear results in a loss of 27% of the gross national product (GDP) [1]. Thus, creating wear-resistant coatings and improving the way they are produced are crucial. Coatings made of metal matrix composite (MMC) can greatly increase surface wear resistance. Recent developments in laser surface processing have led to the development of the tungsten fused carbides (WSC, comprising WC and W2C) reinforced bronze matrix composite (specifically WSC/CuAl10Ni5Fe4) coating. This new MMC coating has an 80% wear reduction potential [2]. However, a strong temperature gradient and significant thermal expansion mismatch between phases cause the MMC coatings to have both macro (type I) and micro (type II) residual strains. The performance in service of the WSC/bronze composite coating is greatly dependent by these residual stresses. For instance, dimensional distortion of the MMC coating results from the release of residual stresses during the servicing process. Additionally, the fatigue strength [3] and service life of the MMC coating [4] are decreased due to unexpected breaking caused by the superposition of residual stresses and applied stress. For these reasons determining the macro and micro residual stresses is crucial.