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激光熔覆技术是利用激光辐射使熔覆材料和基体表面同时熔化并快速凝固、从而显著改善基体材料物理性能的一种新工艺方法。但激光熔覆工艺的选择不当则会使熔覆层产生裂纹、气孔、未熔合等,从而影响熔覆制件的综合性能。本文研究了激光熔覆裂纹的种类以及熔覆层的应力类型,分析了裂纹产生的机理,指出材料间热膨胀系数、弹性模量的明显差别及激光熔池区域的温度梯度所决定的热应力是熔覆层裂纹形成的根源。并从熔覆材料和基体材料的合理选择、成形工艺参数的合理设计及热处理等方面,阐述了熔覆裂纹的影响因素和控制方法。
Laser cladding technology is a new process method that uses laser radiation to melt and rapidly solidify the cladding material and the substrate surface, thereby significantly improving the physical properties of the matrix material. However, the improper choice of laser cladding process will make the cladding cracks, porosity, unmelted, etc., thus affecting the overall performance of cladding parts. In this paper, the types of laser cladding cracks and the type of stress in the cladding layer were studied. The mechanism of crack generation was analyzed. The thermal stress determined by the significant difference of thermal expansion coefficient and elastic modulus between materials and the temperature gradient of the laser pool was Crack formation of the root causes. The influencing factors and control methods of cladding cracks were expounded from the aspects of reasonable selection of cladding materials and matrix materials, rational design of forming parameters and heat treatment.