本文關(guān)鍵詞： 激光-電弧復(fù)合焊接 高強(qiáng)鋼 顯微組織 拉伸強(qiáng)度　出處：《長春理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：激光-電弧復(fù)合焊作為激光焊接技術(shù)中的新興技術(shù),在國內(nèi)外具有較強(qiáng)的競爭力和廣闊的應(yīng)用市場,但是國內(nèi)對激光-電弧復(fù)合焊接技術(shù)的研究較晚,相對一些發(fā)達(dá)國家,我國在這方面的研究相對落后。因此,本論文采用激光-電弧復(fù)合熱源焊接方法,對焊后的高強(qiáng)鋼進(jìn)行微觀組織及力學(xué)性能的基礎(chǔ)分析。(1)首先,在實(shí)驗(yàn)室條件下對低合金調(diào)質(zhì)高強(qiáng)鋼進(jìn)行激光-電弧復(fù)合焊焊接,經(jīng)過打磨拋光等處理后將其制成標(biāo)準(zhǔn)試樣;其次,詳細(xì)介紹了試驗(yàn)過程中涉及的設(shè)備以及測量儀器的機(jī)械結(jié)構(gòu)以及主要功能等;最后,研究了維氏硬度分布規(guī)律、微觀組織形貌以及拉伸性能這三個方面,并且對不同方面給出了不同的研究方法。(2)首先,分析了試樣的顯微維氏硬度,通過研究發(fā)現(xiàn):靠近焊縫區(qū)中心硬度值有降低的趨勢,在焊縫區(qū)和過熱區(qū)之間硬度基本維持在較穩(wěn)定的水平,從正常晶粒區(qū)開始降低,并在軟化區(qū)達(dá)到最低。母材的硬度在400HV左右,除了個別點(diǎn)之外,焊縫和熱影響區(qū)的硬度基本處于500HV到600HV之間,軟化區(qū)的寬度大小在0.6~0.7mm內(nèi),其硬度最低。其次,分析了試樣的微觀組織形貌。通過金相顯微鏡和掃描電子顯微鏡觀察復(fù)合焊接接頭的顯微組織形貌,發(fā)現(xiàn):在熱影響區(qū)組織中沒有發(fā)現(xiàn)新成型的鐵素體組織,并且,從靠近基體位置到靠近融合線的位置,全是板條狀的馬氏體組織。再次,通過對試樣進(jìn)行X射線衍射分析,發(fā)現(xiàn):無論是焊縫區(qū)、熱影響區(qū)還是基體組織都是馬氏體組織。最后,通過對焊縫區(qū)進(jìn)行EDS分析,發(fā)現(xiàn):焊縫區(qū)的主要元素Mn、Cr、Ni的含量基本沒有變化,這也就說明,焊縫區(qū)的組成成分比較一致,硬度基本不變。(3)對試樣進(jìn)行拉伸試驗(yàn)。研究發(fā)現(xiàn),在拉伸過程中,試樣斷裂均發(fā)生在焊縫區(qū),同時,拉伸斷口形貌與拉伸強(qiáng)度有關(guān):強(qiáng)度為573MPa時,斷口缺陷為結(jié)晶裂紋;強(qiáng)度為806MPa時,斷口缺陷為結(jié)晶裂紋和氣孔缺陷;強(qiáng)度為941MPa時,斷口形式為韌窩斷裂和氣孔缺陷;強(qiáng)度為1073MPa時,斷口形式是典型的韌窩斷裂。
[Abstract]:As a new technology in laser welding technology, laser-arc composite welding has strong competitiveness and wide application market at home and abroad. However, the study of laser-arc composite welding technology in China is relatively late, compared with some developed countries. Therefore, in this paper, the laser arc composite heat source welding method is used to analyze the microstructure and mechanical properties of high strength steel after welding. The low alloy quenched and tempered high strength steel was welded by laser-arc composite welding under laboratory conditions. After polishing and polishing, it was made into a standard sample. Secondly, The mechanical structure and main functions of the equipment and measuring instruments are introduced in detail. Finally, the distribution of Vickers hardness, the microstructure and the tensile properties of Vickers hardness are studied. At first, the microhardness of the sample is analyzed. It is found that the hardness value near the center of the weld zone has a tendency to decrease. The hardness between the weld zone and the superheated zone is maintained at a stable level, which decreases from the normal grain area and reaches the lowest in the softening zone. The hardness of the base metal is about 400 HV, except for a few points, the hardness of the base metal is about 400HV, and the hardness of the base metal is about 400HV. The hardness of weld and heat affected zone is between 500HV and 600HV, and the width of softening zone is 0.6 ~ 0.7mm, and the hardness is the lowest. The microstructure of composite welded joints was observed by metallographic microscope and scanning electron microscope. It was found that no newly formed ferrite structure was found in the heat-affected zone. From the position near the matrix to the position near the fusion line, all the martensite structures are strip. Thirdly, by X-ray diffraction analysis of the sample, it is found that: no matter in the weld zone, The heat affected zone and matrix structure are both martensite microstructures. Finally, through the EDS analysis of the weld zone, it is found that the content of the main element of the weld zone is basically unchanged, which means that the composition of the weld zone is consistent. It was found that the fracture occurred in the weld zone during the tensile process, and the tensile fracture morphology was related to the tensile strength: when the tensile strength was 573 MPA, the fracture defect was crystalline crack; When the strength is 806 MPA, the fracture surface is crystalline crack and porosity defect, the fracture form is dimple fracture and pore defect when the strength is 941 MPA, and the fracture form is typical dimple fracture when the strength is 1073 MPA.
【學(xué)位授予單位】：長春理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG456.7

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本文編號：1511722