摘要
采用真空感应熔炼法制备了医用Ti-50. 7%Ni合金(原子数分数),测试了铸态合金的成分、相变点、微观组织和硬度,并采用Gleeble-3800热模拟实验机在变形温度750～950℃、应变速率0. 001～1 s-1,应变量为0. 5的条件下对Ni-Ti合金进行高温压缩变形,分析其流动应力变化规律,建立了高温塑性变形本构关系和热加工图.结果表明:当变形温度减小或应变速率增大时,Ni-Ti合金的流动应力会随之增大.应变速率为1 s^(-1)时,合金的真应力-真应变曲线呈现出锯齿状特征.根据热加工图,获得了Ni-Ti合金的加工安全区和流变失稳区,进而确定其合理的热变形温度范围为820～880℃,真应变速率低于0. 1 s^(-1).从而为制定镍钛合金的锻造工艺参数提供理论和数据基础.
A Ti-50. 7% Ni( atomic fraction) shape alloy was prepared by vacuum induction melting under dynamic argon atmosphere. By analyzing the composition,deformation temperature,microstructure,and hardness of the as-cast Ni-Ti shape alloy in this study,it was found that the properties of the as-cast Ni-Ti alloy met the medical standard. To analyze the variation law of the flow stress,the flow stress of the compression deformation for as-cast Ni-Ti alloy was studied by high-temperature compression with a Gleeble-3800 simulated machine within a deformation temperature range of 750-950 ℃,strain rate range of 0. 001-1. 0 s-1,and strain level of 0. 5. To analyze the relationship between variables in the hot deformation process of as-cast Ni-Ti alloy,a constitutive equation based on dynamic material model was established. To determine the reasonable range of hot working conditions for as-cast Ni-Ti alloy deformation,hot processing maps under different hot deformation conditions were set up. The results show that when the deformation temperature decreases or strain rate increases,the flow stress of as-cast Ni-Ti alloy increases. This phenomenon shows that the main factors affecting the flow stress of as-cast Ni-Ti alloy are deformation temperature and strain rate. When the strain rate is 1. 0 s-1,the true stress-true strain curves of as-cast Ni-Ti alloy exhibits a zigzag feature. This is mainly attributed to the alternation between hardening and softening during deformation. According to the hot processing maps under different hot deformation conditions,the processing zone and unstable hot deformation region of the as-cast Ni-Ti alloy were obtained. Then,the best temperature range of hot deformation is determined as 820-880 ℃,and the true strain rate is less than 0. 1 s-1. This study provides a theoretical and data basis for the development of forging process parameters of Ni-Ti alloy.
作者
王臻
徐效文
王快社
王文
WANG Zhen;XU Xiao-wen;WANG Kuai-she;WANG Wen(Department of Biomedical Engineering,Central South University,Changsha 410083,China;School of Metallurgy Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China)
出处
《工程科学学报》
EI
CSCD
北大核心
2019年第2期238-245,共8页
Chinese Journal of Engineering
基金
甘肃省科技重大专项计划"镍产业链关键技术开发与产业化"资助项目(17ZD2GC011)
