摘要
激光熔覆得到的Ni基合金熔覆层容易出现裂纹,这是导致Ni基合金熔覆层失败的主要因素.基于实验及微观检测分析,以Ni60熔覆层为研究对象,从组织和应力方面对激光熔覆过程中熔覆层裂纹的开裂及扩展机理进行了研究.综合熔覆层微观组织、物相以及断口形貌分析发现,熔覆层不同位置晶体组织差异显著,材料硬度与裂纹敏感性随硬质相分布的增加而升高,Ni60熔覆层的裂纹属于准解理的脆性断裂,裂纹萌生于熔覆层顶部,并沿硬质相向内部规律性扩展.根据热残余应力模型与Griffith脆性断裂强度模型建立了涂层开裂判据,并在此基础上提出相应的裂纹消除方法,改善了金属的性能.
The Ni-based alloy cladding coating obtained by laser cladding is prone to cracking, which is the main factor leading to the failure of the Ni-based alloy cladding coating. Based on the experimental and microscopic measurement and analysis, with Ni60 cladding coating as the research object, the mechanism of cracking and propagation of cracks in laser cladding coatings are studied from the aspects of microstructure and stress. Synthesizing the microstructure, phase and fracture morphology of the cladding coating, it is found that the crystal structure of the cladding coating is significantly different at different locations. The hardness and crack sensitivity of the coating increase with the increase of the hard phase distribution. The crack of Ni60 cladding coating is quasi-dissociation. The brittle fracture occurs at the top of the cladding layer and extends regularly along the interior of the hard phase. Based on the thermal residual stress model and the Griffith brittle fracture strength model, the cracking criterion of the coating is established. Based on this, the corresponding crack elimination method is proposed, the performance of metal is enhanced.
作者
李琦
李涛
吴祖鹏
石博文
张洪潮
LI Qi;LI Tao;WU Zupeng;SHI Bowen;ZHANG Hongchao(School of Mechanical Engineering,Dalian University of Technology,Dalian 116024,China)
出处
《大连理工大学学报》
EI
CAS
CSCD
北大核心
2020年第2期159-164,共6页
Journal of Dalian University of Technology
基金
中央高校基本科研业务费专项资金资助项目(DUT18JC13)
宁夏回族自治区重点研发计划项目(2018BDE0204).
关键词
激光熔覆
NI基合金
裂纹机理
微观组织
热应力
laser cladding
Ni-based alloy
crack mechanism
microstructure
thermal stress
作者简介
李琦(1993-),女,硕士生,E-mail:liqi_2016@163.com;李涛(1977-),女,博士,副教授,硕士生导师,E-mail:litao_dlut@163.com;张洪潮(1953-),男,教授,博士生导师,E-mail:hongchao18@163.com.
