无保护层激光冲击对GH3044涡轮机匣围观组织和性能的影响

Effects of LSPwC on microstructure and properties of GH3044 turbine case

针对激光冲击强化涡轮机匣部件难以贴覆吸收保护涂层的问题,提出无保护层激光冲击(LSPwC)+水砂纸磨除烧蚀层的复合工艺,研究LSPwC对GH3044合金微观组织和力学性能的影响,验证复合工艺的可行性。采用能谱仪(EDS)、扫描电子显微镜(SEM)和金相显微镜分析试样表层元素组成和微观组织,通过测试残余应力和高周疲劳寿命表征其力学性能。结果表明,LSPwC在试样表层产生约10~15μm的烧蚀层,烧蚀层内碳、氧元素富集且残余拉、压应力交替存在,烧蚀层以下晶粒和碳化物不同程度地均匀细化;相比原始试样,LSPwC对GH3044合金疲劳寿命提升不明显;水砂纸磨除烧蚀层后,试样表面残余压应力约510 MPa,影响深度层达1 mm,疲劳寿命提高到原始试样的3倍。

Aiming at the problem of covering absorption and protection coatings on turbine case parts during laser shock processing,a compound technology was put forward,which used water sand paper to polish out the ablative layer after laser shock processing without coating(LSPwC).The effects of LSPwC on microstructure and mechanical properties of GH3044 alloy were researched,the feasibility of the compound technology was verified.Energy disperse spectroscopy(EDS)was used to analyze element composition,the surface microstructure of samples was observed by means of scanning electron microscope(SEM)and metallographic microscope,mechanical properties were studied through residual stress and high cycle fatigue life test.The results show that LSPwC generates an ablative layer on sample surface,which thick 10-15μm range.Carbon and oxygen are rich in the layer,while the residual and tensile compressive stress alternately exist.The grain and carbide under the ablative layer are even-distributed and refined to different degree;Compared to original samples,LSPwC nearly improves the fatigue life of GH3044 alloy.After polishing out the ablative layer by water sand paper,a residual compressive stress,which is about 510 MPa,is generated on surface and the affected depth is about 1 mm.Besides,the fatigue life is improved to be about 3 times compared to original samples.