中文摘要：

激光熔覆是利用高能束激光热源辐射熔覆层和基材表面，使之熔化并迅速凝固，从而显著改善基材性能的一种新的工艺方法。由于熔覆层和基材的物理特性不一样，激光熔覆过程中必然产生热应力，其形态表现为拉应力。熔覆层表面在拉应力的作用下出现裂纹，严重影响了试件的质量。通过实验与建模，分析了熔覆层的应力类型，阐明了裂纹的形成机理，同时对试件进行预热和对熔覆层作微锻造处理，从机理和数学模型两个方面，论证了对熔覆层进行微锻造可以减少或消除熔覆层的拉应力，控制裂纹的产生。

英文摘要：

Laser cladding is a new kind of technical method that utilizes high energy beams of laser heat to radiate cladding layer and matrixes＇ surface and to make it melted and solidified immediately, thus we can improve the performance of the matrixes evidently. Because the physical characteristics of the layer of laser cladding and the matrixes are different, it will give rise to thermal stress in the course of the laser cladding, and its form manifests itself as tensile stress. Under the action of tensile stress, crackles will be seen on the surface of the cladding layer, which affected greatly the quality of the test pieces of the layer of laser cladding. This article analyzed the types of cladding layer＇s stress in layer cladding by testing and modeling, and illustrated the forming mechanism of cladding layer＇s crackles; at the same time, we preheated the test pieces and micro-forged the layer of laser cladding, and proved mechanically mathematically that the micro-forging of the layer of laser cladding can reduce or remove the tensile stress of the layer of laser cladding as well as control the crackles of the layer of laser cladding.