激光冲击强化对加力燃烧室火焰探测器焊缝的影响

为了研究激光冲击强化(LSP)后加力燃烧室火焰探测器焊缝位置异常开裂原因,采用X射线衍射方法和金相方法对激光冲击强化效果进行分析,并利用扫描电子显微镜对断口进行了观察。在Abaqus有限元分析软件中建立了与观察到的焊缝缺陷相似的有限元模型,对焊缝缺陷的LSP处理及冲击波传播过程进行了模拟分析。试验结果表明:具有较好材料完整性的区域经LSP处理后,表面会预置较大残余压应力,同时表面金属晶粒得到细化,疲劳裂纹会在焊缝缺陷位置萌生和扩展。有限元分析结果表明:存在分层缺陷的焊缝经LSP强化后,冲击波会在分层缺陷处产生反射,造成分层位置发生开裂,形成裂纹源造成疲劳开裂。根据试验和仿真分析结果,为提升火焰探测器焊缝激光冲击抗疲劳效果,建议优化焊接工艺,提高焊接质量。

Impact of Laser Shock Peening on Welding Seam of Flame Detector in Afterburner

In order to study the causes of welding seam abnormal cracking of afterburner flame detector after laser shock peening(LSP),X-ray diffraction and metallographic methods were used to analyze the effect of laser shock peening,and the fracture was observed by scanning electron microscope.A finite element model similar to the observed weld seam defects was established in Abaqus finite element analysis software,and the LSP treatment and shock wave propagation process of weld seam defects were simulated and analyzed.The test results show that the area with good material integrity treated by LSP will be reserved with large residual compressive stress on the surface,and the surface metal grains will be refined,and the fatigue cracks initiation and propagation will occured at the weld seam defect location.The finite element analysis results also show that after the weld seam with delamination defect is strengthened by LSP,the shock wave will reflect at the delamination defect,resulting in cracking at the delamination position,forming crack source and fatigue cracking.According to the test and simulation analysis results,in order to improve the fatigue resistance of flame detector weld seam by laser shock,it is suggested to improve welding process and welding quality.