本文選題：6082-T6鋁合金 + 攪拌摩擦焊(FSW)�。� 參考：《蘭州理工大學》2017年碩士論文

【摘要】：隨著交通運輸業(yè)的發(fā)展,能源危機的日益加劇,輕量化技術(shù)受到越來越多的關(guān)注。鋁合金因其密度小、比強度高、耐腐蝕、成型性能優(yōu)良等特點,廣泛運用于列車車體。攪拌摩擦焊可以解決鋁合金焊接比較困難的問題。試驗采用的6082-T6鋁合金由于其良好的焊接性、優(yōu)良的機械加工性能以及較強的耐腐蝕性能,在交通運輸和機械工程行業(yè)的應(yīng)用越來越普遍。本文對2mm厚的6082-T6鋁合金進行攪拌摩擦焊接,焊后采用透射電子顯微鏡(TEM)對攪拌摩擦焊縫組織進行研究,采用掃描電鏡(SEM)分析焊接接頭斷口形貌,同時結(jié)合組織變化對拉伸強度和硬度變化原因進行分析研究。結(jié)果表明:6082-T6鋁合金FSW接頭焊縫上層與焊縫下層組織發(fā)生了變化,各個區(qū)域沉淀相分別為:母材主要是β″;焊核區(qū)為GP區(qū)和尺寸細小的Fe Si2;熱影響區(qū)為β′。由于受到熱輸入作用,各個區(qū)域都發(fā)生了不同程度的動態(tài)回復(fù)和動態(tài)再結(jié)晶。顯微硬度曲線近似為″W″形,硬度最小值出現(xiàn)在前進側(cè)熱影響區(qū)。焊縫區(qū)接頭整體抗拉強度為母材的72%,焊縫區(qū)上層的拉伸強度高于焊縫下層。6082-T6鋁合金FSW接頭匙孔前方中含有β″沉淀相,匙孔后方存在Fe Si2沉淀相。6082-T6鋁合金接頭縱截面顯微硬度在匙孔前后幅值變化較大,匙孔后方硬度顯著降低。焊接接頭硬度從接頭底部到上部,逐漸增大,同時存在的熱影響區(qū)軟化帶逐漸擴大。6082-T6鋁合金攪拌摩擦焊匙孔前方區(qū)域拉伸性能最高,各個區(qū)域都含有夾雜相,不同區(qū)域的斷裂方式都為典型的韌性斷裂。針對6082-T6鋁合金攪拌摩擦焊接頭焊后抗拉強度不高、力學性能較差等原因?qū)嚢枘Σ梁附咏宇^進行自然時效和人工時效處理,結(jié)果表明:人工時效處理后顯微硬度比焊態(tài)和自然時效高10-25HV,人工時效對提高焊核區(qū)和熱機影響區(qū)硬度明顯高于自然時效。經(jīng)過焊后自然時效、人工時效的焊接接頭力學性能得到一定程度的提升,人工時效比自然時效抗拉強度提高12%,延伸率降低9%,人工時效提高拉伸強度效果更明顯。由于鋁合金FSW接頭組織成分不均勻,同一焊縫可能會發(fā)生多種腐蝕類型,通過對腐蝕后的FSW接頭鋁合金微觀組織形貌進行觀察,結(jié)合電化學試驗發(fā)現(xiàn):6082-T6鋁合金攪拌摩擦焊接試樣在焊縫中間區(qū)域的耐腐蝕性能最好,母材的耐腐蝕性能性能次于匙孔后方和匙孔前方。6082-T6鋁合金母材和匙孔前方和匙孔后方發(fā)生腐蝕類型主要為晶間腐蝕和剝落腐蝕,隨著時間增加,晶間腐蝕和剝落腐蝕程度加劇。焊縫中間區(qū)域基本不發(fā)生腐蝕。
[Abstract]:With the development of transportation industry and the intensification of energy crisis, the lightweight technology is being paid more and more attention. Aluminum alloy is widely used in train body because of its small density, high strength, corrosion resistance and good molding performance. Friction stir welding can solve the difficult problem of aluminum alloy welding. The 6082-T6 aluminum alloy used in the experiment is used. Because of its good weldability, excellent mechanical processing property and strong corrosion resistance, gold is becoming more and more popular in the transportation and mechanical engineering industry. In this paper, 2mm thick 6082-T6 aluminum alloy was welded by friction stir welding. After welding, transmission electron microscope (TEM) was used to study the structure of friction stir welds, and the scan was scanned. The fracture morphology of welded joints was analyzed by SEM, and the changes of tensile strength and hardness were analyzed with microstructure changes. The results showed that the upper layer of the weld seam of the 6082-T6 aluminum alloy FSW joint and the underlayer of the weld seam changed, and the precipitates in each region were mainly beta, the weld core area was GP and the size of Fe S. I2, the heat affected zone is beta '. Due to the heat input, the dynamic recovery and dynamic recrystallization have occurred in various degrees. The microhardness curve is approximately "W" shape, and the minimum hardness value appears in the forward side heat affected zone. The overall tensile strength of the weld zone joint is 72% of the base material, and the tensile strength of the upper seam zone is higher than that of the weld seam. In the front of the lower.6082-T6 aluminum alloy FSW joint spoon hole, there is a beta precipitation phase in front of the key hole. Behind the keyhole, the microhardness of the longitudinal section of the.6082-T6 aluminum alloy joint with the Fe Si2 precipitation phase changes greatly before and after the keyhole, and the hardness in the rear of the keyhole is significantly reduced. The hardness of the welding joint is gradually increased from the bottom to the upper part of the joint, and the heat affected zone is softened. The tensile property in front of the friction welding spoon hole with gradual expansion of.6082-T6 aluminum alloy is the highest, all regions contain inclusions, and the fracture modes in different regions are typical ductile fracture. The friction welding joints of 6082-T6 aluminum alloy friction stir welding joints are not high after welding, and the mechanical properties are poor. The results of natural aging and artificial aging treatment show that the microhardness of artificial aging is higher than that of welding state and natural aging, and the hardness of artificial aging is obviously higher than that of natural aging. After natural aging after welding, the mechanical properties of the welded joint of artificial aging are improved to a certain extent, and the artificial aging is made by artificial aging. The tensile strength is increased by 12% than that of natural aging, and the elongation is reduced by 9%. The effect of artificial aging on tensile strength is more obvious. Due to the uneven microstructure of the FSW joint of aluminum alloy, many kinds of corrosion types may occur in the same weld seam. The microstructure of the aluminum alloy after corrosion of the FSW joint is observed and the electrochemical test is found to find 6082-T6 The corrosion resistance performance of the aluminum alloy friction stir welding specimens is the best in the middle area of the weld. The corrosion resistance performance of the parent material is second to the rear of the keyhole and the front of the.6082-T6 aluminum alloy and the key hole in front of the keyhole. The corrosion types are mainly intergranular corrosion and peeling corrosion behind the spoon hole, and the intergranular corrosion and the exfoliation corrosion process are increased with time. There is no corrosion in the middle area of the weld.
【學位授予單位】：蘭州理工大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TG453.9

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