【摘要】：隨著微系統(tǒng)技術(shù)(MST)、微機(jī)電系統(tǒng)(MEMS)、醫(yī)療工程領(lǐng)域的迅猛擴(kuò)展,對微型化零部件的市場需求與日俱增,加速了微制造產(chǎn)業(yè)的興起和發(fā)展。然而在微成形中,由于尺寸效應(yīng)的影響,采用傳統(tǒng)的塑性加工理論難以解釋材料的變形行為,限制了微成形的工業(yè)化生產(chǎn),因此有必要對尺寸效應(yīng)進(jìn)行研究。本文在實(shí)驗(yàn)室研究了不同退火工藝條件下晶粒尺寸對純銅薄板的力學(xué)性能的影響,采用微軋制實(shí)驗(yàn)、數(shù)值模擬和XRD等方法研究了晶粒尺寸和壓下率對純銅在微軋制過程中不均勻變形、邊裂、顯微組織和織構(gòu)演變規(guī)律的影響。主要研究結(jié)果如下:(1)隨晶粒尺寸增大,純銅薄板的延伸率和抗拉強(qiáng)度逐漸降低,拉伸試樣斷口表面的微孔數(shù)目明顯減少。(2)隨晶粒尺寸增大,軋件邊部不均勻變形增加,邊部凸起越來越明顯,寬展不均勻增加,材料的塑性越來越不穩(wěn)定,軋制力逐漸減小,軋制力不穩(wěn)定性增加。隨著壓下率增大,軋件邊部不均勻變形增加,邊部凸起越來越明顯,寬展不均勻增加,軋件整體的不均勻變形增加。(3)當(dāng)壓下率為80%、晶粒尺寸為65μm時(shí),軋件開始出現(xiàn)邊裂,但裂痕較小;當(dāng)晶粒尺寸增大到200μm時(shí),邊裂增大,裂痕加深;當(dāng)晶粒尺寸為200μm時(shí),壓下率小于60%時(shí)無邊裂出現(xiàn);當(dāng)壓下率增大到80%時(shí),開始出現(xiàn)邊裂。(4)變形較大時(shí),晶粒被拉長,顯微組織呈片層狀結(jié)構(gòu);隨著晶粒尺寸增大,晶粒沿軋制方向被拉長;當(dāng)晶粒增大到200μm時(shí),晶粒呈連續(xù)片層狀結(jié)構(gòu);當(dāng)軋件晶粒尺寸不變時(shí),隨著壓下率增大,晶粒逐漸被壓扁拉長,沿軋制方向呈現(xiàn)出片層狀。(5)當(dāng)壓下率為80%、晶粒尺寸為20μm到65μm之間時(shí),織構(gòu)類型保持不變,軋件的織構(gòu)強(qiáng)度略有變化,表現(xiàn)為較強(qiáng)的{112}111Copper織構(gòu)和{123}634S織構(gòu);當(dāng)晶粒尺寸增大到200μm時(shí),{112}111Copper織構(gòu)和{123}634S織構(gòu)明顯減弱,織構(gòu)類型演變?yōu)樵俳Y(jié)晶織構(gòu);當(dāng)軋件晶粒尺寸不變時(shí),隨著壓下率增大,{112}111Copper織構(gòu)和{123}634S織構(gòu)強(qiáng)度逐漸增大,{001}100Cube織構(gòu)逐漸減弱。
[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.
【學(xué)位授予單位】：遼寧科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TG339;TG146.11

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本文編號：2456092