初始片层组织BT25y合金加工硬化行为研究  

Work Hardening Behavior of BT25y Alloy with Initial Lamellar Microstructure

作　　者：杨雪梅 闫学伟 史晓楠 郭鸿镇[4] Yang Xuemei;Yan Xuewei;Shi Xiaonan;Guo Hongzhen(School of Aerospace Engineering,Zhengzhou University of Aeronautics,Zhengzhou 450046,China;School of Aero Engine,Zhengzhou University of Aeronautics,Zhengzhou 450046,China;School of Civil Aviation,Zhengzhou University of Aeronautics,Zhengzhou 450046,China;School of Materials Science and Engineering,Northwestern Polytechnical University,Xi'an 710072,China)

机构地区：[1]郑州航空工业管理学院航空宇航学院,河南郑州450046 [2]郑州航空工业管理学院航空发动机学院,河南郑州450046 [3]郑州航空工业管理学院民航学院,河南郑州450046 [4]西北工业大学材料学院,陕西西安710072

出　　处：《稀有金属》2023年第9期1213-1220,共8页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(51904276);河南省高等学校重点科研项目(20A430032);河南省重点研发与推广专项(232102230052,222102220093)资助。

摘　　要：基于热模拟压缩试验研究了初始片层组织BT25y合金的加工硬化行为,分析了热变形参数对合金高温力学行为和显微组织演变的影响规律,探究了变形过程中产生加工硬化和流动软化的原因,得到了应变硬化指数在不同变形温度和应变速率的分布情况。结果表明:BT25y合金的应力-应变曲线在小应变处(≤0.07)的急剧升高,源自于位错大量增殖及其缠结和塞积造成的加工硬化,峰值应变之后流动应力的下降归因于绝热温升、流动失稳、片层组织的弯折和球化引起的流动软化。变形量较小时(20%),BT25y合金显微组织与变形初始组织差别不大;变形量增加至40%,与压缩轴平行的片层α相发生严重弯折,与压缩轴近似垂直的α片层发生旋转且沿金属流动方向被压扁,部分片层发生解体断裂,生成短棒状或近球形的α晶粒;变形量进一步增大到60%时,多数α片在片层弯折处发生断裂,剩余少量α片层相界面不再平滑,在α/β相界面处形成大量的热蚀沟槽。初始片层组织BT25y合金的应变硬化指数在不同变形温度下几乎全部为负值,说明流动软化在变形过程中占据主导作用,由于(α+β)两相区低温变形阶段较为充分的片层组织动态球化,该区域表现出较高的n值分布。BT25y titanium alloy is a kind of(α+β)thermal strength titanium alloy with good mechanical properties,which can be used to manufacture the dual-property compressor blisk in aero-engines working at 425~550℃.As the high temperature plastic deformation of titanium alloys is controlled by the dynamic interaction between work hardening and flow softening with increasing deformation amount,the study of work hardening behavior of BT25y titanium alloy is essential and beneficial to realize the regulation of hightemperature mechanical behavior and microstructure characteristics,and improve the comprehensive mechanical performance of BT25y forgings.The work hardening behavior of BT25y alloy with initial lamellar microstructure has been studied through thermal simulation compression test.The thermal simulation compression test was carried out on the Gleeble-3500 thermal simulated test machine within deformation temperatures of 850,880,910,940,970,1000 and 1030℃,strain rates of 0.001,0.01,0.1,1 and 10 s^(-1)and deformations amounts of 20%,40% and 60%.During hot compression,the thermal simulator automatically recorded the true stress and true strain data corresponding to different deformation parameters.After hot deformation,the samples were immediately quenched to room temperature to retain the high-temperature deformed microstructure.According to the true stress-true strain curves and the high-temperature deformed microstructure,the effect of deformation parameters on the high-temperature mechanical behavior and microstructure evolution was analyzed,the causes of work hardening and flow softening during hot deformation were investigated,and the strain hardening exponent distribution under different deformation temperatures and strain rates was calculated.The research results showed that the dramatic stress increased on the true stress-true strain curves at strains smaller than 0.07 derived from work hardening by the massive dislocation multiplication,tangles and pile-ups.The kinking and globularization of α lamellae

关 键 词：BT25y合金 片层组织 力学行为 组织演化 加工硬化 

分 类 号：TG319[金属学及工艺—金属压力加工]