本文選題：7A04鋁合金　切入點(diǎn)：變形溫度　出處：《中北大學(xué)》2011年碩士論文

【摘要】：超高強(qiáng)度鋁合金由于具有質(zhì)量輕、比強(qiáng)度高、韌性較好、熱加工性能好以及可熱處理等優(yōu)良的性能，一直在交通運(yùn)輸、航空航天、節(jié)能減排等領(lǐng)域發(fā)揮著重要的作用。在鋁合金棒材的生產(chǎn)和加工過(guò)程中，不可避免的會(huì)帶有一定強(qiáng)度地纖維狀晶粒和織構(gòu)。而它們所引起的各向異性會(huì)對(duì)鋁合金材料的塑性變形產(chǎn)生嚴(yán)重的影響。因此如何控制纖維狀晶粒和織構(gòu)的不良影響，并最大程度的利用它們發(fā)揮出鋁合金的潛在力學(xué)性能，，一直是材料工程領(lǐng)域重要的課題。 本文采用室溫拉伸實(shí)驗(yàn)、高溫壓縮實(shí)驗(yàn)、金相觀察、x-射線(xiàn)衍射等分析方法研究了在不同變形溫度下7A04鋁合金力學(xué)性能與微觀組織的變化規(guī)律，旨在為熱加工制度的制定、合金組織與性能的預(yù)測(cè)和控制等提供參考。 對(duì)變形溫度的研究表明，變形初期(達(dá)到真應(yīng)力峰值前)，流動(dòng)應(yīng)力隨應(yīng)變的增加而迅速增加，當(dāng)應(yīng)變超過(guò)一定值后，流動(dòng)應(yīng)力開(kāi)始稍微下降并逐漸趨于穩(wěn)定，出現(xiàn)了穩(wěn)態(tài)流動(dòng)特征；在給定應(yīng)變速率的條件下，流動(dòng)應(yīng)力隨著溫度的升高而顯著降低，且合金流動(dòng)應(yīng)力進(jìn)入穩(wěn)態(tài)流動(dòng)時(shí)所需的應(yīng)變也隨著溫度的升高而減小。對(duì)材料的金相觀察表明：隨著壓縮變形溫度的升高，晶粒會(huì)有明顯長(zhǎng)大的現(xiàn)象。 對(duì)應(yīng)變速率的研究表明，7A04鋁合金在320℃壓縮載荷作用下，在與合金棒材擠壓方向成O。、90。兩個(gè)方向下，應(yīng)變率敏感性部比較低；而在400℃、480℃時(shí)鋁合金對(duì)應(yīng)變速率非常敏感。對(duì)材料的金相觀察表明：在溫度不變時(shí)，在低應(yīng)變速率(ε=0．1s~(-1))和高應(yīng)變速率(ε=1s~(-1))壓縮載荷作用下變形時(shí)，晶粒的大小沒(méi)有明顯的變化。 對(duì)各向異性的研究表明，在常溫拉伸狀態(tài)(ε=1.3×10~(-3)s~(-1))下和在低應(yīng)變速率(ε=0．1s~(-1))、溫度較低(T=320。C)的熱模擬壓縮狀態(tài)下時(shí)，7A04鋁合金在O。、45。、90。三個(gè)方向上的力學(xué)性能差異較大。隨著溫度的升高，材料的力學(xué)性能趨于各向同性。 織構(gòu)檢測(cè)發(fā)現(xiàn):材料中有典型“銅型”和“黃銅型”特征織構(gòu),強(qiáng)度分別為6級(jí)和8級(jí)。還有少量的立方織構(gòu)和戈斯織構(gòu),強(qiáng)度都為3級(jí)。在纖維狀晶粒和織構(gòu)的耦合作用下,使合金產(chǎn)生了各向異性。
[Abstract]:Ultra high strength Aluminum Alloy due to the advantages of light weight, high strength, good toughness, good thermal processing performance and heat treatment and other excellent properties, has been in the transportation, aerospace, energy conservation and other areas play an important role in the production and processing Aluminum Alloy bar, inevitably with certain the strength of fibrous grain and texture. And their anisotropy caused by plastic deformation will have a serious impact on Aluminum Alloy materials. So how to control the adverse effects of fibrous grain and texture, and they use the maximum potential mechanical properties of Aluminum Alloy, has been an important task in material engineering field.
The room temperature tensile test, high-temperature compression test, metallographic observation, x- ray diffraction analysis method to study the variation at different deformation temperatures and mechanical properties and microstructure of 7A04 Aluminum Alloy, aims to develop for the thermal processing system, provide reference for the alloy microstructure and properties prediction and control.
Study shows that the deformation temperature, initial deformation (really reach the peak stress before), the flow stress increases rapidly with the increase of strain, when the strain exceeds a certain value, the flow stress was slightly decreased gradually stabilized, the steady flow characteristics; at a given strain rate under the condition of flow stress with the increase of temperature and significantly decreased, and the alloy flow stress and strain are required to enter steady state flow also decreases with the increase of temperature. The material metallographic observation showed that: with the deformation temperature, the grain will be significantly long big phenomenon.
Study on the strain rate showed that 7A04 Aluminum Alloy compression load at 320 DEG C, in O. alloy extrusion direction, 90. in two directions, strain rate sensitivity of relatively low; and in 400 C, 480 C Aluminum Alloy is sensitive to the strain rate. The material that observe the metallographic observation: at the same temperature, at low strain rate (=0.1s~ (-1)) and high strain rate (=1s~ (-1)) deformation under compression, the grain size did not change significantly.
Study on anisotropy show that in tensile state (=1.3 * 10~ (-3) s~ (-1)) and at low strain rate (=0.1s~ (-1)) and low temperature (T=320.C) of the thermal simulation compression state, 7A04 Aluminum Alloy in O., 45., mechanical 90. the three directions can differ greatly. With the increase of temperature, the mechanical properties of the material tends to be isotropic.
Texture detected: typical "copper" and "brass" characteristics of textured materials, strength were 6 and 8. There is a small amount of cube texture and texture of Goss, the strength of 3. In the coupling of fibrous grain and texture, so that the alloy has anisotropy.

【學(xué)位授予單位】：中北大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2011
【分類(lèi)號(hào)】：TG146.21

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