A comprehensive study of thermal damage consequent to laser surface treatment

This paper gives a comprehensive description of thermal damage introduced by a laser surface treatment (LST) and the possibility to build a quantified damage model. Through experimentation and a finite element (FE) simulation, a deep analysis was carried out on the final microstructure, microhardness and residual stress of specimens subjected to LST under different laser powers. According to the study, the phase-transition-induced microstructure change, which can be reflected by microhardness value, is deemed the essential of thermal damage. Residual stress is another product resulted from the thermal process. A scalar is suggested to have a general description of thermal damage quantitatively, which is supposed to be the function of microhardness, residual stress and the material discontinuity. Its value falls into the range of 0-1. As hardness and residual stress are tightly related to the material strength, further work is expected to detail this model, based on the mechanism of how the hardness features and residual stress affect the material strength, to build a coupled model of thermal damage and strength.