A method for evaluating the crack resistance and predicting the preheating temperature of high hardness coating prepared by laser cladding

A novel test method was proposed to evaluate the crack resistance of high hardness coating prepared by laser cladding based on the self-restraint test in welding. In this method, the crack resistance of the coating was reflected by the crack rate, which was controlled by the restraint of the specimen. Consequently, the relationship between the restraint and the depth/width of the Y-groove could be demonstrated. As the depth of the Y-groove increased, the restraint of the specimen rose, while the increasing width of the Y-groove led to the decrease of the restraint of the specimen. Besides, the method was available for evaluating the crack resistance of different high hardness coatings. The evaluation results presented in excellent agreement with experimental data obtained by the tensile test. Furthermore, the empirical formulas of the relationship between the product of strength and plasticity, the crack rate, the depth, and the width of the Y-groove were also established. Besides, the high hardness crack-free coatings were prepared with appropriate preheating temperatures obtained by this method. The crack resistance test proposed in this study provided a general method for evaluating and preparing high hardness crack-free coatings.