非均质铜及铜锌合金的力学行为研究
发布时间：2018-09-18 14:35
【摘要】：本文通过采用Cu和Cu-30%Zn金属作为两种研究材料,采用一种设计多级构筑纳米金属结构的思路,即首先通过大塑性变形细化晶粒,随后再利用部分再结晶退火引入部分再结晶晶粒,以此来获得一种非均质的纳米金属结构材料。通过大塑性变形技术和热处理工艺的参数调控来获得最佳拉伸强度与均匀延伸率的匹配。对变形机理的研究思路为结合位错理论与包申格效应,再通过微结构表征,对非均质纳米金属的拉伸应变硬化行为进行分析。(1)Cu:粗晶组织Cu经过2道次的ECAP剪切变形,晶粒得到有效细化,再采用短时退火引入部分再结晶,以获得非均质纳米结构。利用室温准静态拉伸实验得到不同结构的应力应变响应。通过循环加卸载拉伸试验研究非均质纳米Cu中的包申格效应,对粗晶和非均质结构所表现出来的不同背应力硬化行为对比研究。循环应力松弛拉伸试验可以有效表征纳米金属在准静态拉伸变形过程中的激活体积和可动位错密度演化,进而将纳米金属的林位错行为及其硬化机制进行阐明。对粗晶和非均质结构Cu的循环应力松弛拉伸结果进行对比,各自给出林位错硬化机制与微结构的演化关系。最后对粗晶和非均质Cu进行DIC全场应变测量,从宏观变形的角度,完整地把各自不同的应变硬化行为展现出来。(2)Cu-30%Zn:通过大应变冷轧将粗晶Cu-30%Zn的屈服强度从100MPa提高到了750 MPa。加部分再结晶退火后,对热处理工艺进行不同尝试,以获得了较好的强度塑性匹配。在300℃退火30 min后材料可以达到最好的强度塑性匹配,屈服强度为约600 MPa,均匀拉伸塑性为20%。同样对其做循环加卸载拉伸试验探究非均质的低层错能材料在拉伸变形过程中的包申格效应与背应力硬化,以研究背应力硬化对加工硬化能力的提升作用。通过EBSD表征证明该材料在拉伸变形过程中发生了孪生变形,进一步证明低层错能材料在拉伸变形的过程中不再是单纯以位错的滑移为主导的变形机制,而是变成了以孪生为主导的变形机制。另外,通过低温下的准静态拉伸性能结果与室温准静态拉伸对比,结合EBSD表征,分析低温下Cu-30%Zn的强韧化效果与应变硬化行为。此外,高应变速率下的拉伸应力应变响应研究了其对应变速率敏感性。
[Abstract]:In this paper, Cu and Cu-30%Zn metals are used as two kinds of research materials, and a multi-level design method is used to construct nanocrystalline structure. Firstly, grain refinement is made by large plastic deformation, and then partial recrystallization grain is introduced by partial recrystallization annealing, and then part recrystallization grain is introduced by partial recrystallization annealing. In order to obtain a heterogeneous nanometallic structure material. The best match of tensile strength and uniform elongation is obtained by means of large plastic deformation technique and parameter control of heat treatment process. The research idea of deformation mechanism is to combine dislocation theory with Bauschinger effect, and then analyze the tensile strain hardening behavior of heterogeneous nanometers by microstructure characterization. (1) Cu of Cu: coarse grain structure has undergone two ECAP shearing deformation. The grain was refined effectively and the partial recrystallization was introduced by short time annealing to obtain heterogeneous nanostructures. The stress-strain response of different structures was obtained by quasi-static tensile test at room temperature. The Bauschinger effect in heterogeneous nanocrystalline Cu was studied by cyclic loading and unloading tensile tests. The different back stress-hardening behaviors of coarse crystal and heterogeneous structure were compared. Cyclic stress relaxation tensile test can effectively characterize the evolution of activation volume and movable dislocation density of nanometallic metals during quasi-static tensile deformation, and then explain the stand dislocation behavior and hardening mechanism of nanometallic materials. The cyclic stress relaxation and tensile results of coarse grained and heterogeneous Cu were compared and the relationship between dislocation hardening mechanism and microstructure evolution was given. Finally, the DIC full-field strain measurement of coarse grain and heterogeneous Cu is carried out. From the angle of macroscopic deformation, the different strain-hardening behaviors of Cu-30%Zn: are presented completely. (2) the yield strength of coarse grain Cu-30%Zn is increased from 100MPa to 750 MPa. by Cu-30%Zn: cold rolling with large strain. After partial recrystallization annealing, different attempts were made on the heat treatment process to obtain a better strength and plasticity match. After annealing at 300 鈩，
本文编号：2248221
[Abstract]:In this paper, Cu and Cu-30%Zn metals are used as two kinds of research materials, and a multi-level design method is used to construct nanocrystalline structure. Firstly, grain refinement is made by large plastic deformation, and then partial recrystallization grain is introduced by partial recrystallization annealing, and then part recrystallization grain is introduced by partial recrystallization annealing. In order to obtain a heterogeneous nanometallic structure material. The best match of tensile strength and uniform elongation is obtained by means of large plastic deformation technique and parameter control of heat treatment process. The research idea of deformation mechanism is to combine dislocation theory with Bauschinger effect, and then analyze the tensile strain hardening behavior of heterogeneous nanometers by microstructure characterization. (1) Cu of Cu: coarse grain structure has undergone two ECAP shearing deformation. The grain was refined effectively and the partial recrystallization was introduced by short time annealing to obtain heterogeneous nanostructures. The stress-strain response of different structures was obtained by quasi-static tensile test at room temperature. The Bauschinger effect in heterogeneous nanocrystalline Cu was studied by cyclic loading and unloading tensile tests. The different back stress-hardening behaviors of coarse crystal and heterogeneous structure were compared. Cyclic stress relaxation tensile test can effectively characterize the evolution of activation volume and movable dislocation density of nanometallic metals during quasi-static tensile deformation, and then explain the stand dislocation behavior and hardening mechanism of nanometallic materials. The cyclic stress relaxation and tensile results of coarse grained and heterogeneous Cu were compared and the relationship between dislocation hardening mechanism and microstructure evolution was given. Finally, the DIC full-field strain measurement of coarse grain and heterogeneous Cu is carried out. From the angle of macroscopic deformation, the different strain-hardening behaviors of Cu-30%Zn: are presented completely. (2) the yield strength of coarse grain Cu-30%Zn is increased from 100MPa to 750 MPa. by Cu-30%Zn: cold rolling with large strain. After partial recrystallization annealing, different attempts were made on the heat treatment process to obtain a better strength and plasticity match. After annealing at 300 鈩，
本文编号：2248221
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