| 引用本文: | 李胜,雷远涛,伍文星,申龙章,陈勇,朱红梅,邱长军.激光熔覆镍基高温耐磨合金的组织及性能*[J].中国表面工程,2023,36(5):213~221 |
| LI Sheng,LEI Yuantao,WU Wenxing,SHEN Longzhang,CHEN Yong,ZHU Hongmei,QIU Changjun.Microstructure and Properties of Laser Cladding Ni-based High-temperature Wear-resistant Alloy[J].China Surface Engineering,2023,36(5):213~221 |
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| 摘要: |
| 通过增加 IN718 合金中（Ti+Al）含量制备一种镍基高温耐磨合金，以满足超临界机组镍基合金阀门密封面再制造的需求。采用万能试验机、摩擦磨损试验机、XRD、SEM 等仪器和 JMatpro 软件研究该合金激光熔覆试样的组织与性能。研究结果如下：当 IN718 合金的（Ti+Al）含量增加至 7.6 %时熔覆层会出现开裂；当 IN718 合金的（Ti+Al）含量增加至 6.6 % 时，其激光熔覆试样初始平均硬度值为 40 HRC，抗拉强度为 998 MPa，延伸率为 5.2 %，室温摩擦因素为 0.75 左右，磨损量为 0.327 5 mm3 ，主相为 γ 相和 γ′相，700 ℃×10 h 时效处理后平均硬度值为 54 HRC，700 ℃摩擦因素为 0.35 左右，磨损量为 0.024 mm3 ，主相 γ′占 53 %。研究结果表明，IN718 合金中（Ti+Al）含量增加至 6.6 %时具有良好的激光熔覆工艺性能和高温摩擦磨损性能，可应用于超临界 / 超超临界机组镍基合金阀门密封面的维修与再制造。 |
| 关键词: 激光熔覆 镍基高温合金 摩擦磨损 阀门密封面 组织结构 |
| DOI：10.11933/j.issn.1007?9289.20221110002 |
| 分类号:TG115；TB114 |
| 基金项目:国防科技重点实验室基金（JCKY61420052002）；中央军委装备发展部装备预研基金（61400040204）；湖南省研究生科研创新（223YSC009）资助项目 |
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| Microstructure and Properties of Laser Cladding Ni-based High-temperature Wear-resistant Alloy |
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LI Sheng, LEI Yuantao, WU Wenxing, SHEN Longzhang, CHEN Yong, ZHU Hongmei, QIU Changjun
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Hunan Provincial Key Laboratory of Equipment Safety Service Technology under Abnormal Environment,University of South China, Hengyang 421001 , China
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| Abstract: |
| IN718 is a nickel-based high-temperature alloy with economic performance that is widely used in manufacturing of hot-end components with ambient temperatures not exceeding 650 ℃. Its structural composition includes the γ phase as the matrix; the γ″ phase is the main strengthening phase and the γ′ phase is an auxiliary strengthening phase. In response to the insufficient high-temperature wear-resistance of the nickel-based alloy valve-sealing surface of generator units operating in supercritical / ultra-supercritical environments, two improved nickel-based high-temperature wear-resistant alloy powders were prepared based on IN718 alloy by increasing its (Ti+Al) content to 6.6% and 7.6% to improve performance. The proportion of γ′ precipitate phases and some brittle and hard phases greatly improve the high-temperature wear-resistance of the alloy, meeting the manufacturing and remanufacturing requirements of nickel-based alloy valve-sealing surfaces in supercritical units. A nickel-based high-temperature wear-resistant alloy sample was prepared on 304 stainless steel substrate using laser cladding deposition technology. The room temperature tensile properties of the sample were tested using a universal testing machine. The wear resistance of the sample with (Ti+Al) content up to 6.6% was tested by a high-temperature friction and wear testing machine at room temperature and 700 ℃. The microstructure of the IN718im2 laser cladding sample was studied using XRD and SEM. The phase proportions in IN718 and IN718im2 were calculated using JMatpro software. The results are presented as follows. When the (Ti+Al) content of IN718 alloy was increased to 7.6%, a large transverse crack appeared in the cladding layer. At this point, the SEM morphology of the sample surface showed a large number of δ phases and other brittle phases. The hardness values of the IN718im2 sample before and after heat treatment were 41.22 HRC and 55.6 HRC, respectively. When the (Ti+Al) content of IN718 alloy was increased to 6.6%, the initial average hardness of the laser cladding sample was 40 HRC, the tensile strength was 998 MPa, the elongation was 5.2%, the room temperature friction factor was approximately 0.75, and the wear was 0.327 5 mm3 after 10 h of aging treatment at 700 ℃. The average hardness was 54 HRC, the friction coefficient at 700 ℃ was approximately 0.35, and the wear was 0.024 mm3 . The proportions of γ and γ′ phases were 18.19% and 53.5%, respectively. The wear resistance of the IN718im2 sample at 700 ℃ was better than that at room temperature because Nb, Ti, and Al promote in situ formation of a glaze layer, and Ti and Al promote high-temperature self-lubrication of the alloy. The content of (Ti+Al) in IN718im2 was much higher than that in IN718; the proportion of brittle and hard phases was also much higher. The SEM surface scanning results showed that the segregation of Al and Ti was relatively weak; Mo and Nb had obvious segregation, indicating that increasing the (Ti+Al) content within a certain range did not exacerbate segregation of Ti and Al. However, the cracks in the sample with a (Ti+Al) content of 7.6% indicate that excessive Ti and Al contents promote great precipitation of brittle phases and increase dislocation accumulation and stress concentration, leading to formation of cracks in the cladding layer. The results indicate that when the content of (Ti+Al) in IN718 alloy increases to 6.6%, it has good laser cladding process performance and high-temperature friction and wear performance, suitable for use in manufacturing and remanufacturing of nickel-based alloy valve-sealing surfaces in supercritical / ultra-supercritical units, and providing a reference for development of nickel-based high-temperature alloys in laser additive manufacturing. |
| Key words: laser cladding nickel-based superalloy friction and wear valve-sealing surface microstructure |
