轧制压下率、路径对NiCoCr合金微观结构和力学性能的影响  

The effects of cold rolling thickness reduction and path on the microstructure and mechanical properties of NiCoCr alloy

作　　者：冯天 孔见[2] 张勇 赵永好[2] FENG Tian;KONG Jian;ZHANG Yong;ZHAO Yonghao(Nanjing University of Science and Technology,Herbert Gleiter Institute of Nanoscience,Nanjing 210094,China;Nanjing University of Science and Technology,School of Materials Science and Engineering,Nanjing 210094,China)

机构地区：[1]南京理工大学格莱特纳米科技研究所,南京210094 [2]南京理工大学材料科学与工程学院,南京210094

出　　处：《有色金属科学与工程》2024年第2期212-219,共8页Nonferrous Metals Science and Engineering

基　　金：国家自然科学基金资助项目(51601091);江苏省前沿引领技术基础研究重大项目(BK20222014)。

摘　　要：通过开展不同轧制压下率和路径的轧制实验,制备了具有不同比例和尺寸的纳米孪晶和纳米晶结构NiCoCr合金。透射电镜表征结果表明,单向轧制压下率50%样品中微观结构特征以纳米孪晶和高密度位错为主。当压下率达到90%,由于剪切带在纳米孪晶片层结构中的开动,孪晶体积分数下降,同时剪切带内形成大量尺寸为35 nm的纳米晶结构。多方向轧制样品中微观结构以纳米晶结构为主,平均尺寸为27 nm,略小于单向轧制压下率90%样品中的纳米晶尺寸。拉伸实验结果表明:相比于轧制前固溶态粗晶合金,单向轧制压下率50%纳米孪晶镍基合金强度大幅提高,合金屈服强度和抗拉强度分别达到1312 MPa和1396 MPa。压下率90%轧制样品屈服强度高达1599 MPa,变方向轧制样品屈服强度更是高达1705 MPa。同时拉伸试验数据表明,晶粒细化可以有效地提高材料强度,但是材料的延伸率显著下降。Bulk NiCoCr alloy samples with different volume fraction of nano-twins and nano-grains were fabricated by cold rolling with various thickness reduction and strain path.Transmission electron microscopy observations indicate that the microstructure in the one-directional rolled sample with 50%thickness reduction is characterized by nano-twins and high density of dislocations.With increasing the rolling thickness reduction to 90%,the volume fraction of nano-twins decreases due to the activation of shear banding within the nano-twined lamellar area,which consequently leads to the formation of massive nano-grains with average sizes of 35 nm.The microstructure of the multi-directional rolled sample is mainly composed of nano-grains with main sizes of 27 nm,which is slightly smaller than that of one-directional rolled sample.Tensile test results show that the strength of the one-directional rolled sample with 50%thickness reduction is significantly enhanced with yield strength and ultimate tensile strength reaching 1312 MPa and 1396 MPa,respectively,which is much higher as compared to the coarse-grained alloy with solid solution heat treatment.The yield strength is further increased to 1599 MPa with thickness reduction reaching 90%,and multiple-directional rolling gives rise to a higher yield strength of 1705 MPa.Tensile testing results indicated that the grain refinement could significantly increase the strength,but deteriorate the ductility to some extent.

关 键 词：轧制 镍基合金 力学性能 纳米孪晶 晶粒细化 

分 类 号：TG335.12[金属学及工艺—金属压力加工]