Ⅰ级涡轮叶片线性缺陷分析
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摘要
发动机在工厂试车考核后分解检查时,发现其中一件Ⅰ级涡轮叶片表面有线性荧光显示。通过金相、扫描电镜等手段,对失效叶片进行断口形貌观察、组织及成分分析,并与同种材料金相光面、冲击断面的表面氧化形貌进行对比,确定线性缺陷的性质及产生原因。结果表明:线性缺陷是由富含Ti、Mo碳化物的膜状缺陷导致的开裂,起因是在浇铸过程中合金液表面发生翻动或飞溅挂壁时形成氧化物薄膜,在后续时效过程中沿氧化物薄膜析出该膜状碳化物;膜状缺陷开裂后经过长时间高温氧化,在开裂面形成由Ni、Co的氧化物为主的外氧化层和由Cr、Al、Ti的氧化物为主的内氧化层组成的双层复合氧化膜。在生产过程中,可采用过滤网、提高真空度、保持平稳浇注来避免此类缺陷的产生。
A linear fluorescence defect was found on the surface of one of the 1 st turbine blades when a certain type of engine was decomposed for inspection after the factory test run. The fracture morphology, microstructure and composition of the failed blade were observed and analyzed by means of metallography and scanning electron microscopy, etc. Its surface oxidation morphology was compared with the oxidized morphology of the same material's metallographic smooth surface and impact section. The nature of the linear defect and its cause were determined. The results show that the linear defect of the blade is a cracking caused by a membrane-like defect rich in Ti and Mo carbides. The reason is that the oxide film was formed when the surface of the alloy liquid rotated or splattered on the wall during the casting process, and then the membrane-like carbides were precipitated along the oxide film in the subsequent aging process. The membrane-like defects cracks and undergoes a long period of high temperature oxidation,which forms a two-layer composite oxide film with an outer oxide layer mainly composed of the oxides of Ni and Co and an inner oxide layer mainly composed of the oxides of Cr, Al and Ti. We can use a filter, increase the vacuum and maintain a smooth pouring to avoid such defects in the production process.
A linear fluorescence defect was found on the surface of one of the 1 st turbine blades when a certain type of engine was decomposed for inspection after the factory test run. The fracture morphology, microstructure and composition of the failed blade were observed and analyzed by means of metallography and scanning electron microscopy, etc. Its surface oxidation morphology was compared with the oxidized morphology of the same material's metallographic smooth surface and impact section. The nature of the linear defect and its cause were determined. The results show that the linear defect of the blade is a cracking caused by a membrane-like defect rich in Ti and Mo carbides. The reason is that the oxide film was formed when the surface of the alloy liquid rotated or splattered on the wall during the casting process, and then the membrane-like carbides were precipitated along the oxide film in the subsequent aging process. The membrane-like defects cracks and undergoes a long period of high temperature oxidation,which forms a two-layer composite oxide film with an outer oxide layer mainly composed of the oxides of Ni and Co and an inner oxide layer mainly composed of the oxides of Cr, Al and Ti. We can use a filter, increase the vacuum and maintain a smooth pouring to avoid such defects in the production process.
引文
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[2]韩晓东,杨秀娟.航空发动机涡轮叶片修复中的裂纹控制[J].科技创新与应用,2017(36):166–167.
[3]代朋超,魏志刚,王资兴,等.一种镍基高温合金黑斑缺陷的组织分析及形成机理研究[J].宝钢技术,2014(5):49–53.
[4]宁礼奎.四种镍基高温合金的抗热腐蚀性能研究[D].大连:大连理工大学,2008.
[5]郭国谊.高温合金薄壁复杂铸件的失蜡铸造工艺优化[J].铸造技术,2015,36(10):2607–2609.
[6]任占友,吴亚夫,谢秋峰,等.高温合金某薄壁铸件铸造缺陷工艺控制[J].铸造,2015,64(12):1231–1233.
[7]王超,李振瑞,牛永吉.动力学方法解决高温合金铸件中心疏松与二次缩孔的应用研究[J].金属材料研究,2016(1):27–33.
[8]任忠鸣.航空发动机涡轮叶片研究[J].江苏钢铁,2017(19):83–87.
[9]吕明,陈文琳,甘瑞霞.真空铸造下镍基高温合金铸件氧化膜缺陷分析[J].韶关学院学报,2014,35(8):45–49.
[10]李维银,刘红飞,王婷,等.新型镍基高温合金长期时效后的组织稳定性及高温性能[J].机械工程材料,2008,32(7):64–67.
[11]李维银,刘红飞,赵双群.新型镍基高温合金950℃氧化行为的研究[J].材料热处理学报,2008,29(3):26–29.
[12]黄嘉鹏,杨斌,汪航.镍铬铝合金的高温氧化行为[J].有色金属科学与工程,2015,6(4):41–45.