本文關(guān)鍵詞： 雙面雙弧MIG焊 對(duì)接接頭 T型接頭 預(yù)熱溫度 數(shù)值仿真　出處：《吉林大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：隨著經(jīng)濟(jì)發(fā)展和社會(huì)城市化建設(shè)造成的能源危機(jī)和環(huán)境污染問題不斷加劇,城市軌道客車必然是向著輕量化、節(jié)能和環(huán)保的方向發(fā)展。鋁合金具有質(zhì)量輕、強(qiáng)度高、加工性能好、抗腐蝕性能強(qiáng)等優(yōu)點(diǎn),因而增加城市軌道客車中鋁合金的使用量是實(shí)現(xiàn)城市軌道客車輕量化最直接有效的方法之一。目前,城市軌道客車生產(chǎn)中鋁合金的焊接結(jié)構(gòu)一般采用手工電弧焊和半自動(dòng)焊,工藝落后,產(chǎn)品的質(zhì)量穩(wěn)定性差,一次焊接合格率低,生產(chǎn)周期長(zhǎng),生產(chǎn)效率低,并且工人勞動(dòng)強(qiáng)度大。因此,本文研究了一種中厚板鋁合金雙面雙弧MIG焊工藝方法,并對(duì)關(guān)鍵工藝問題進(jìn)行探究,此工藝減少了工序的復(fù)雜程度,免除了清根工序,節(jié)約了材料,大大提高了焊接效率,對(duì)鋁合金在城市軌道客車中的廣泛應(yīng)用具有重要的理論意義和實(shí)用價(jià)值。本文首先研究了6082-T6鋁合金雙面雙弧MIG焊對(duì)接接頭和T型接頭的微觀組織的特點(diǎn)及力學(xué)性能。研究結(jié)果表明,鋁合金雙面雙弧MIG焊對(duì)接接頭和T型接頭試樣的宏觀形貌均分為焊縫區(qū)、熔合區(qū)和熱影響區(qū)三部分。當(dāng)預(yù)熱溫度為100℃,焊接電弧前后間距為0 mm時(shí),對(duì)接接頭打底焊的焊縫金屬熔厚最大;當(dāng)預(yù)熱溫度為100℃,T型接頭的根部間隙為3 mm時(shí),T型接頭打底焊的焊縫金屬熔厚最大。鋁合金雙面雙弧MIG焊對(duì)接接頭和T型接頭試樣的微觀組織從焊縫區(qū)到熔合區(qū)依次為樹枝晶和柱狀晶,晶粒尺寸的大小會(huì)隨著熱輸入量的增大而增大,且焊縫側(cè)的柱狀晶晶粒的尺寸要大于母材側(cè)柱狀晶晶粒的尺寸。當(dāng)T型接頭的根部間隙較小和預(yù)熱溫度過低時(shí),接頭容易出現(xiàn)氣孔、裂紋和未熔合的焊接缺陷。鋁合金雙面雙弧MIG焊接頭的焊縫區(qū)有Mg2Si析出。研究發(fā)現(xiàn),鋁合金雙面雙弧MIG焊對(duì)接接頭和T型接頭熱影響區(qū)的顯微硬度低于焊縫區(qū)的顯微硬度,對(duì)接接頭熱影響區(qū)的寬度隨著預(yù)熱溫度的升高和焊接電弧前后間距的增大而加寬;T型接頭熱影響區(qū)的寬度隨著預(yù)熱溫度的增大而加寬,同時(shí)隨著根部間隙的增大呈現(xiàn)先增大后減小的現(xiàn)象,且當(dāng)根部間隙為3 mm時(shí)寬度最大。鋁合金雙面雙弧MIG焊對(duì)接接頭的抗拉強(qiáng)度和屈服強(qiáng)度,隨著預(yù)熱溫度的升高和焊接電弧前后間距的增大而有所下降,拉伸斷口呈典型的韌窩結(jié)構(gòu),為韌性斷裂。當(dāng)預(yù)熱溫度為100℃、焊接電弧前后間距為0 mm時(shí),鋁合金雙面雙弧MIG焊對(duì)接接頭的彎曲試樣合格率最高,彎曲性能最好。通過對(duì)雙面雙弧焊對(duì)接接頭和T型接頭的溫度場(chǎng)和應(yīng)力場(chǎng)進(jìn)行數(shù)值仿真分析發(fā)現(xiàn),在合適的工藝條件下,對(duì)接接頭和T型接頭試件兩側(cè)的熱輸入基本對(duì)稱,并且能夠形成共同熔池;應(yīng)力場(chǎng)的計(jì)算結(jié)果表明雙面雙弧焊工藝不僅能夠調(diào)整試件的殘余應(yīng)力分布,而且在一定程度上能夠降低殘余應(yīng)力的水平,這對(duì)工件的工藝性以及使用性能都是有利的。
[Abstract]:With the economic development and social urbanization caused by the energy crisis and environmental pollution, urban rail passenger cars are bound to develop towards the direction of lightweight, energy saving and environmental protection. Aluminum alloy has light quality. High strength, good processing performance, strong corrosion resistance and other advantages, so increasing the use of aluminum alloy in urban rail cars is one of the most direct and effective methods to realize the lightweight of urban rail cars. Manual arc welding and semi-automatic welding are generally used in welding structure of aluminum alloy in the production of urban rail cars. The process is backward, the quality stability of the products is poor, the qualification rate of primary welding is low, the production cycle is long, and the production efficiency is low. And the labor intensity of workers is high. Therefore, this paper studies a double-arc MIG welding process for medium and thick aluminum alloy, and probes into the key process issues, this process reduces the complexity of the process. The utility model eliminates the root cleaning process, saves the material and greatly improves the welding efficiency. It has important theoretical significance and practical value for the wide application of aluminum alloy in urban rail passenger cars. In this paper, the microstructure of 6082-T6 aluminum alloy double-side double-arc MIG butt joint and T-joint is studied firstly. The characteristics and mechanical properties of the fabric. The macroscopic morphology of double arc MIG welding butt joint and T type joint of aluminum alloy is divided into three parts: weld zone, fusion zone and heat affected zone. The preheating temperature is 100 鈩，

本文編號(hào)：1480371