纯铜微轧制晶粒尺寸效应与数值模拟研究

发布时间：2019-04-10 20:12

【摘要】：随着微系统技术(MST)、微机电系统(MEMS)、医疗工程领域的迅猛扩展,对微型化零部件的市场需求与日俱增,加速了微制造产业的兴起和发展。然而在微成形中,由于尺寸效应的影响,采用传统的塑性加工理论难以解释材料的变形行为,限制了微成形的工业化生产,因此有必要对尺寸效应进行研究。本文在实验室研究了不同退火工艺条件下晶粒尺寸对纯铜薄板的力学性能的影响,采用微轧制实验、数值模拟和XRD等方法研究了晶粒尺寸和压下率对纯铜在微轧制过程中不均匀变形、边裂、显微组织和织构演变规律的影响。主要研究结果如下:(1)随晶粒尺寸增大,纯铜薄板的延伸率和抗拉强度逐渐降低,拉伸试样断口表面的微孔数目明显减少。(2)随晶粒尺寸增大,轧件边部不均匀变形增加,边部凸起越来越明显,宽展不均匀增加,材料的塑性越来越不稳定,轧制力逐渐减小,轧制力不稳定性增加。随着压下率增大,轧件边部不均匀变形增加,边部凸起越来越明显,宽展不均匀增加,轧件整体的不均匀变形增加。(3)当压下率为80%、晶粒尺寸为65μm时,轧件开始出现边裂,但裂痕较小;当晶粒尺寸增大到200μm时,边裂增大,裂痕加深;当晶粒尺寸为200μm时,压下率小于60%时无边裂出现;当压下率增大到80%时,开始出现边裂。(4)变形较大时,晶粒被拉长,显微组织呈片层状结构;随着晶粒尺寸增大,晶粒沿轧制方向被拉长;当晶粒增大到200μm时,晶粒呈连续片层状结构;当轧件晶粒尺寸不变时,随着压下率增大,晶粒逐渐被压扁拉长,沿轧制方向呈现出片层状。(5)当压下率为80%、晶粒尺寸为20μm到65μm之间时,织构类型保持不变,轧件的织构强度略有变化,表现为较强的{112}111Copper织构和{123}634S织构;当晶粒尺寸增大到200μm时,{112}111Copper织构和{123}634S织构明显减弱,织构类型演变为再结晶织构;当轧件晶粒尺寸不变时,随着压下率增大,{112}111Copper织构和{123}634S织构强度逐渐增大,{001}100Cube织构逐渐减弱。
[Abstract]:With the rapid expansion of micro-system technology (MST), micro-electro-mechanical system (MEMS),) medical engineering field, the market demand for micro-parts is increasing day by day, which accelerates the rise and development of micro-manufacturing industry. However, due to the influence of size effect in micro-forming, it is difficult to explain the deformation behavior of materials by traditional plastic working theory, which limits the industrial production of micro-forming, so it is necessary to study the size effect. In this paper, the effect of grain size on the mechanical properties of pure copper sheet under different annealing conditions was studied in laboratory. The effects of grain size and reduction rate on the inhomogeneous deformation, edge crack, microstructure and texture evolution of pure copper during micro rolling were studied by numerical simulation and XRD. The main results are as follows: (1) with the increase of grain size, the elongation and tensile strength of pure copper sheet decrease gradually, and the number of micropores on the fracture surface of tensile specimens decreases obviously. (2) with the increase of grain size, the number of micropores on the fracture surface of tensile specimens decreases obviously. The non-uniform deformation of the edge increases, the protruding of the edge becomes more and more obvious, the width increases unevenly, the plasticity of the material becomes more and more unstable, the rolling force decreases gradually, and the instability of the rolling force increases. With the increase of the reduction rate, the non-uniform deformation of the edge of the rolling piece increases, the bulge of the edge becomes more and more obvious, the spread of the strip increases unevenly, and the non-uniform deformation of the rolling piece increases. (3) when the reduction rate is 80% and the grain size is 65 渭 m, the non-uniform deformation of the rolling piece increases. The edge crack appears at first, but the crack is small. When the grain size increases to 200 渭 m, the edge crack increases and the crack deepens, and when the grain size is 200 渭 m, the edge crack occurs when the reduction rate is less than 60%. When the reduction rate increases to 80%, edge cracks begin to appear. (4) when the deformation is large, the grain is elongated and the microstructure is lamellar, and with the increase of grain size, the grain is elongated along the rolling direction. When the grain size increases to 200 渭 m, the grain has a continuous lamellar structure. When the grain size of the rolled piece is constant, the grain is gradually flattened and elongated along the rolling direction with the increase of the reduction rate. (5) when the reduction rate is 80% and the grain size is between 20 渭 m and 65 渭 m, the texture type remains the same, while the grain size is between 20 渭 m and 65 渭 m, and the grain size is between 20 渭 m and 65 渭 m. The texture strength of the rolled piece changed slightly, showing strong {112} 111Copper texture and {123} 634S texture. When the grain size increases to 200 渭 m, the {112} 111Copper texture and {123} 634S texture obviously weaken, and the texture type evolves to recrystallization texture. When the grain size is constant, the {112} 111Copper texture and {123} 634S texture strength increase with the increase of the reduction rate, and the {001} 100Cube texture decreases gradually.
【学位授予单位】：辽宁科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG339;TG146.11

【参考文献】