工程科学学报，第38卷，第10期：1429-1437,2016年10月 Chinese Journal of Engineering,Vol.38,No.10:1429-1437,October 2016 D0l:10.13374/j.issn2095-9389.2016.10.012:http://journals..ustb.edu.cn 增压涡轮用K424高温合金组织特征及热裂倾向性 赵 展，董建新，张麦仓，郑磊，姚志浩 北京科技大学材料科学与工程学院，北京100083 ☒通信作者，E-mail:chaozhan_0831@163.com 摘要针对K424精密铸造增压涡轮叶片出现的热裂问题，采用组织观察和计算模拟的方法，分析增压涡轮用K424合金特 性以及涡轮叶片铸造中出现热裂的原因，并对比K418合金提出合金热裂倾向性的影响因素以及减少热裂的建议.结果表 明，铸造增压涡轮热裂倾向性与合金特性及铸件特性等有关.K424合金中A!和T元素含量较高，导致合金中共晶组织含量 多且尺寸大，与K418合金相比，热裂倾向性较大：另一方面，由于铸件叶片位置厚度小且曲率变化大，易形成应力集中，导致 热裂.为减小热裂倾向性，需控制K424合金中A1和T元素含量并选择合理的工艺参数. 关键词镍基高温合金：力学性能：组织特征：凝固 分类号TG132.3:TG146.1·5 Microstructure and susceptibility to hot tearing of K424 nickel-based superalloys for turbocharger turbine wheels ZHAO Zhan,DONG Jian-in,ZHANG Mai-cang,ZHENG Lei,YAO Zhi-hao School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China Corresponding author,E-mail:zhaozhan_0831@163.com ABSTRACT Hot tearing tends to occur when K424 superalloy is used for a turbocharger turbine wheel.To solve this problem,the alloy characteristics of K424 and K418 superalloys and the factors impacting the susceptibility to hot tearing were studied by micro- structure observations and casting simulations.The research proposed the main factors which affected the susceptibility to hot tearing and also the method to reduce hot tearing in the turbine wheel.It is found that the susceptibility to hot tearing of the turbine wheel is influenced by both the alloy characteristics and casting characteristics.K424 superalloy shows a higher susceptibility to hot tearing when compared with K418.Because of high amount of aluminum and titanium in K424 superalloy,the size and the amount of y+y' eutectics increase,resulting in more prior forming and propagating areas of hot tearing.On the other hand,due to a smaller thickness and a larger curvature change in the blade margin of the turbine wheel,the uneven distribution of the thermal stress is induced in the end of the solidification process,which leads to hot tearing in this paper.In order to decrease the susceptibility to hot tearing of the turbine wheel,the contents of aluminum and titanium should be controlled,and the reasonable technological parameters of casting should be set to ensure the final effect. KEY WORDS nickel-based superalloys:mechanical properties;microstructure characteristics:solidification 涡轮增压器是利用发动机排气中的剩余能量来工 涡轮，其转速通常为(3~11)×10r·min,柴油发动 作的空气泵.采用涡轮增压技术，可以在发动机尺寸 机增压涡轮的工作温度为650~850℃，某些汽油发动 不变的条件下产生更大的功率，有利于降低发动机整 机的增压涡轮温度甚至高达950~1030℃，叶片上受 体重量，减少摩擦，改善燃烧，降低排放和噪音，实现环 到多种交变应力的作用，同时要求其工作寿命达到 保节能四.涡轮增压器的核心部件为由热废气推动的 103~I0h.复杂而严苛的服役环境要求增压器涡轮 收稿日期：201507一14工程科学学报，第 38 卷，第 10 期: 1429--1437，2016 年 10 月 Chinese Journal of Engineering，Vol． 38，No． 10: 1429--1437，October 2016 DOI: 10． 13374 /j． issn2095--9389． 2016． 10． 012; http: / /journals． ustb． edu． cn 增压涡轮用 K424 高温合金组织特征及热裂倾向性 赵 展，董建新，张麦仓，郑 磊，姚志浩 北京科技大学材料科学与工程学院，北京 100083  通信作者，E-mail: zhaozhan_0831@ 163． com 摘 要 针对 K424 精密铸造增压涡轮叶片出现的热裂问题，采用组织观察和计算模拟的方法，分析增压涡轮用 K424 合金特 性以及涡轮叶片铸造中出现热裂的原因，并对比 K418 合金提出合金热裂倾向性的影响因素以及减少热裂的建议． 结果表 明，铸造增压涡轮热裂倾向性与合金特性及铸件特性等有关． K424 合金中 Al 和 Ti 元素含量较高，导致合金中共晶组织含量 多且尺寸大，与 K418 合金相比，热裂倾向性较大; 另一方面，由于铸件叶片位置厚度小且曲率变化大，易形成应力集中，导致 热裂． 为减小热裂倾向性，需控制 K424 合金中 Al 和 Ti 元素含量并选择合理的工艺参数． 关键词 镍基高温合金; 力学性能; 组织特征; 凝固 分类号 TG132. 3; TG146. 1 + 5 Microstructure and susceptibility to hot tearing of K424 nickel-based superalloys for turbocharger turbine wheels ZHAO Zhan ，DONG Jian-xin，ZHANG Mai-cang，ZHENG Lei，YAO Zhi-hao School of Materials Science and Engineering，University of Science and Technology Beijing，Beijing 100083，China  Corresponding author，E-mail: zhaozhan_0831@ 163． com ABSTＲACT Hot tearing tends to occur when K424 superalloy is used for a turbocharger turbine wheel． To solve this problem，the alloy characteristics of K424 and K418 superalloys and the factors impacting the susceptibility to hot tearing were studied by micro￾structure observations and casting simulations． The research proposed the main factors which affected the susceptibility to hot tearing and also the method to reduce hot tearing in the turbine wheel． It is found that the susceptibility to hot tearing of the turbine wheel is influenced by both the alloy characteristics and casting characteristics． K424 superalloy shows a higher susceptibility to hot tearing when compared with K418． Because of high amount of aluminum and titanium in K424 superalloy，the size and the amount of γ + γ' eutectics increase，resulting in more prior forming and propagating areas of hot tearing． On the other hand，due to a smaller thickness and a larger curvature change in the blade margin of the turbine wheel，the uneven distribution of the thermal stress is induced in the end of the solidification process，which leads to hot tearing in this paper． In order to decrease the susceptibility to hot tearing of the turbine wheel，the contents of aluminum and titanium should be controlled，and the reasonable technological parameters of casting should be set to ensure the final effect． KEY WOＲDS nickel-based superalloys; mechanical properties; microstructure characteristics; solidification 收稿日期: 2015--07--14 涡轮增压器是利用发动机排气中的剩余能量来工 作的空气泵． 采用涡轮增压技术，可以在发动机尺寸 不变的条件下产生更大的功率，有利于降低发动机整 体重量，减少摩擦，改善燃烧，降低排放和噪音，实现环 保节能［1］． 涡轮增压器的核心部件为由热废气推动的 涡轮，其转速通常为( 3 ～ 11) × 104 r·min － 1，柴油发动 机增压涡轮的工作温度为 650 ～ 850 ℃，某些汽油发动 机的增压涡轮温度甚至高达 950 ～ 1030 ℃，叶片上受 到多种交变应力的作用，同时要求其工作寿命达到 103 ～ 104 h． 复杂而严苛的服役环境要求增压器涡轮