一种新型Ni-Cr-Co基合金的热变形行为及其组织演变  

Hot Deformation Behavior and Microstructure Evolution of New-Type Ni-Cr-Co Based Alloy

作　　者：王兴茂 丁雨田 高钰璧 闫康 马元俊 陈建军 Wang Xingmao;Ding Yutian;Gao Yubi;Yan Kang;Ma Yuanjun;Chen Jianjun(State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,School of Material Science and Engineering,Lanzhou University of Technology,Lanzhou 730050,China)

机构地区：[1]兰州理工大学材料科学与工程学院,省部共建有色金属先进加工与再利用国家重点实验室,甘肃兰州730050

出　　处：《稀有金属材料与工程》2022年第1期249-259,共11页Rare Metal Materials and Engineering

基　　金：国家重点研发计划(2017YFA0700703);国家科学自然基金(51661019);甘肃省科技重大专项(145RTSA004)。

摘　　要：采用Gleeble-3800热压缩试验机研究了新型Ni-Cr-Co基合金在1050~1250℃、0.001~1s^(-1)条件下的热变形行为,并利用EBSD探讨了变形温度和应变速率对合金组织演变和动态再结晶形核机制的影响。结果表明,流变应力随变形温度的升高而降低,而随应变速率的增大而增加。基于流变应力曲线,建立合金的Arrhenius本构方程和热加工图,得到热变形激活能为520.03 kJ/mol,最佳热加工区间条件为1175~1250℃、0.006~1 s^(-1),该区域最大功率耗散效率为45%。动态再结晶分数随变形温度的升高和应变速率的降低而增加,且动态再结晶过程形成了均匀细小的等轴晶粒以及∑3孪晶界。动态再结晶形核主要以晶界"弓出"为特征的不连续动态再结晶机制主导。低温高应变速率下,持续亚晶转动诱导的连续动态再结晶作为辅助形核机制发挥作用。Hot deformation behavior of a new-type Ni-Cr-Co based alloy was investigated by thermal compression tests under the deformation temperature range of 1050~1250 ℃ and strain rate range of 0.001~1 s^(-1). The electron backscatter diffraction(EBSD)technique was employed to investigate the effects of deformation temperature and strain rate on the microstructure evolution of the alloy and nucleation mechanisms of dynamic recrystallization. The result shows that the flow stress decreases with the increasing of the deformation temperature and the decreasing of strain rate. The Arrhenius constitutive equation and hot processing map of the alloy were established based on the hot deformation data, and the hot deformation activation energy was calculated as 520.03 kJ/mol. The optimum hot processing interval is at the temperature scope of 1175~1250 ℃ and the strain rate range of 0.006~1 s^(-1) with the peak power dissipation efficiency of 45%. The fraction of dynamic recrystallization increases with the increasing of deformation temperature and the decreasing of strain rate. And during dynamic recrystallization, a large number of deformed grains are replaced by fine equiaxial grains and a high frequency of ∑3 twin boundaries generates. The dominant dynamic recrystallization nucleation mechanism is grain boundary bulging, which is a typical feature of discontinuous dynamic recrystallization. In the low temperature and high strain rate r egion,continuous dynamic recrystallization characterized by the rotation of subgrains is detected. However, continuous dynamic recrystallization is just an assistant nucleation mechanism for the alloy.

关 键 词：新型Ni-Cr-Co基合金 热变形行为 加工图 动态再结晶 

分 类 号：TG132.32[一般工业技术—材料科学与工程]