变功率激光熔覆镍基涂层裂纹特性研究

为解决航空发动机热端叶片的高损耗现状,提高叶片的表面性能以延长服役寿命,通过对镍基高温合金K417G表面进行变参数激光熔覆制备GH3536涂层,并通过光学显微镜、扫描电子显微镜、XRD衍射仪等仪器对熔覆层的宏观微观形貌进行观察并结合EDS能谱仪元素分布及偏析结果综合检测结果研究激光功率变化带来的熔覆层的成型质量以及性能影响。分析了熔覆层表面区域以及和基体结合区的裂纹缺陷程度以及缺陷形成原因,并通过对比激光功率变化带来的元素偏析影响与裂纹分布的关系,达到工艺参数优化的目的。熔覆层与基材结合界面呈波浪状,且于一定范围内,随着激光功率提升,熔覆层与基体组织交界区域的裂纹明显减少。熔覆层中元素偏析情况,随激光功率降低愈发明显以及伴随晶枝组织的生长方向偏转现象。

Study on crack characteristics of nickel based coating cladding by variable power laser

In order to solve the current situation of high loss of aero engine hot end blade and improve the surface performance of the blade to extend the service life,GH3536 coating was prepared by variable parameter laser cladding on the surface of nickel based superalloy K417G,and the macroscopic and microscopic morphology of the cladding layer is observed by optical microscope,scanning electron microscope,XRD diffractometer and other instruments and combined with EDS energy spectrometer element distribution and segregation.Combined with the comprehensive detection results of element distribution and segregation results of EDS spectrometer,the influence of laser power change on the forming quality and performance of the cladding layer is studied.The degree of crack defects in the surface area of the cladding layer and the bonding area with the matrix and the cause of the defects are analyzed,and the relationship between the effect of element segregation and crack distribution caused by the change of laser power is compared to achieve the purpose of optimization of process parameters.The bonding interface between the cladding layer and the substrate is wavy,and within a certain range,with the increase of the laser power,the cracks at the interface between the cladding layer and the matrix structure are significantly reduced.The element segregation in the cladding layer becomes more obvious with the decrease of laser power and the deflection of the growth direction of the crystal branch structure.