激光与光电子学进展, 2019, 56 (11): 111401, 网络出版: 2019-06-13
激光熔覆Ni基合金裂纹的形成机理及敏感性 下载: 1067次
Formation Mechanism and Sensitivity of Cracks in Laser-Cladded Ni-Based-Alloy Coatings
摘要
采用同轴送粉激光熔覆技术,在45钢表面制备了Ni基合金熔覆层。通过断口分析推断裂纹类型和断裂方式,并结合能谱分析研究了裂纹的萌生和扩展机理。同时,研究了激光熔覆主要工艺参数对开裂敏感性的影响。结果表明,激光熔覆Ni基合金的裂纹断面特征为准解理断裂,属于脆性断裂;熔覆层中的热残余应力导致裂纹在界面处萌生并向涂层表面扩展,硼化物、碳化物等硬质相不良分布以及脆性共晶组织提高了开裂敏感性;工艺参数对熔覆层的开裂敏感性具有较大影响。最终提出了激光熔覆Ni基合金涂层裂纹控制的基本策略。
Abstract
In this study, the Ni-based-alloy coatings are prepared on 45 steel substrates by laser cladding with coaxial powder feeding. The fracture morphology analysis is conducted to evaluate the fracture mode and types of cracks. In addition, the energy-disperse spectroscopy is used to further investigate the mechanisms of crack initiation and propagation. Furthermore, the effects of the laser-cladding-process parameters on the cracking sensitivity are studied. The results show that the cracks in the Ni-based-alloy coatings are due to the quasi-cleavage fractures, which are a type of brittle fracture. Moreover, it is shown that the thermal residual stress causes the crack initiation at the interface and the subsequent crack propagation to the coating surface. It is further shown that the process parameters have significant impacts on the cracking sensitivity of the coating because the uneven distribution of the hard phase (including boride and carbide) and the brittle eutectic organization result in a high cracking sensitivity. Finally, the basic strategies for controlling cracks during laser cladding of Ni-based-alloy coatings are proposed.
张磊, 陈小明, 刘伟, 姜志鹏, 赵鹏, 刘德有. 激光熔覆Ni基合金裂纹的形成机理及敏感性[J]. 激光与光电子学进展, 2019, 56(11): 111401. Lei Zhang, Xiaoming Chen, Wei Liu, Zhipeng Jiang, Peng Zhao, Deyou Liu. Formation Mechanism and Sensitivity of Cracks in Laser-Cladded Ni-Based-Alloy Coatings[J]. Laser & Optoelectronics Progress, 2019, 56(11): 111401.