45kW高功率CO_2激光熔覆过程中裂纹行为的实验研究

对Ｓｔｅｌｌｉｔｅ合金和ＮＩＣｒＳｉＢ合金在高功率激光熔覆下的裂纹现象和行为进行了实验研究。表明Ｓｔｅｌｌｉｔｅ合金对裂纹不敏感，能获得表面光洁、内部致密、无缺陷的熔覆层。ＮｉＣｒＳｉＢ合金对裂纹非常敏感，往往出现大量横向宏观裂纹。ＮＩＣｒＳｉＢ合金的裂纹主要起源于熔覆层与基体的交界面，裂纹通常向熔覆层扩展而穿过整个熔覆，多道搭接时，裂纹会向前道和后道横向传递。裂纹属冷裂纹范畴。裂纹的产生和行为是由熔覆层凝固过程中产生的应力（应变）与熔覆材料的强度和塑性之间的动态相互作用所决定的，并与熔覆材料自身的物理特性以及凝固特性和凝固组织有关。

Experimental Research on Cracking Behavior during 45kW High Power CO_2 Laser Cladding

This paper presents the experimental research results and analyses on cracking behavior during high power laser cladding of Stellite alloy and NiCrSiB alloy. The experiments demonstrate that Stellite alloy is not sensitive to cracking and good quality clad is available. Large area stellite laser clad (length 200mm,width 56mm,depth 1.9mm) was achieved by 18 multipasses. NiCrSiB alloy is very sensitive to cracking and many transverse macro cracks appear on the clad pass. Most cracks originate from the interface between the clad layer and the substrate and then develop up into the surface. During multi-pass,the as happened cracks will develop into the previous passes and later passes. The cracking during laser cladding NiCrSiB alloy belongs to the cold-cracking. The cracking phenomenon and behavior is mainly affected by the dynamic inter action between the stress and/or thermal plasticity of the clad material developed during the solidification,which is related to the physical properties of the cladding material and the solidification characteristics and microstructure.