【摘要】：S620Q厚板低碳調(diào)質(zhì)鋼廣泛應(yīng)用于機械、礦山等領(lǐng)域，焊接作為其應(yīng)用中最主要的連接方式，焊接性能直接關(guān)系到設(shè)備構(gòu)件的安全可靠運行。近年來，運用實驗研究和數(shù)值模擬相結(jié)合的方法研究厚板的焊接性能日益受到關(guān)注。因此本文通過對40mm厚S620Q高強厚板分別進行實芯焊絲氣體保護焊（GMAW）和藥芯焊絲氣體保護焊（FCAW）焊接實驗，利用掃描電鏡及拉伸試驗等分析手段研究了焊接接頭各道焊層的組織轉(zhuǎn)變和力學(xué)性能變化規(guī)律。為了更好的研究S620Q厚板多層多道焊接，本文同時運用ANSYS有限元軟件采用雙橢球熱源模型得到S620Q鋼多層多道焊接溫度場分布規(guī)律，并對厚板各道焊層熱影響區(qū)（HAZ）寬度進行了預(yù)測。在溫度場計算的基礎(chǔ)上，，通過熱－結(jié)構(gòu)間接耦合法與實際殘余應(yīng)力測試，得出焊接接頭殘余應(yīng)力的分布規(guī)律。 焊接實驗表明， GMAW和FCAW工藝條件下，實芯焊縫主要組織為針狀鐵素體(AF)+粒狀貝氏體(GB)，藥芯焊縫組織為GB+少量AF；藥芯接頭焊縫的平均強度略高于實芯焊縫，而且接頭硬度分布水平高于實芯焊縫。熱輸入較小時，實芯粗晶區(qū)組織為LB，藥芯為ML，隨著熱輸入的增大，實芯粗晶區(qū)組織轉(zhuǎn)變?yōu)榇执驦B，藥芯轉(zhuǎn)變?yōu)镚B；沖擊試驗表明，實芯焊縫沖擊值高于藥芯焊縫，而藥芯熔合區(qū)、粗晶區(qū)沖擊值略高于實芯粗晶區(qū)。受到二次熱循環(huán)作用，粗晶區(qū)晶界處生成了不規(guī)則、島狀M-A和貝氏體，部分淬火區(qū)晶界處為GB，但粗晶區(qū)晶界處不規(guī)則、島狀M-A對韌性損害較小。 通過數(shù)值模擬得到了S620Q厚板多層多道焊接溫度場和應(yīng)力場分布規(guī)律；實測熱循環(huán)曲線與模擬計算HAZ的熱循環(huán)曲線變化規(guī)律相同，最高峰值溫度與實測值相比，最大誤差為14%；數(shù)值模擬計算的HAZ各區(qū)域?qū)挾扰c實際測得的HAZ各區(qū)域?qū)挾然疚呛�。厚板焊后殘余拉�?yīng)力主要分布在焊縫及其附近區(qū)域，最大等效殘余拉應(yīng)力為437MPa，X形坡口焊根處具有較大橫向殘余拉應(yīng)力為500MPa；厚度方向上發(fā)生位移量為0.968mm的面外角變形；模擬殘余應(yīng)力曲線與厚板實測值變化趨勢一致。 通過對S620Q高強厚板的GMAW和FCAW焊接實驗及數(shù)值模擬結(jié)果進行分析研究，為S620Q厚板在實際焊接中選擇合適的焊接方法及工藝參數(shù)，改善高強厚板的焊接質(zhì)量，提供一定的實驗依據(jù)。
[Abstract]:S620Q thick plate low carbon quenched and tempered steel is widely used in machinery, mining and other fields. Welding is the most important connection mode in its application. The welding performance is directly related to the safe and reliable operation of equipment components. In recent years, the research of welding performance of thick plate by means of experimental research and numerical simulation has been paid more and more attention. Therefore, through the experiments of 40mm thick S620Q high strength thick plate, the experiments of real cored wire gas shielded welding (GMAW) and flux cored wire gas shielded (FCAW) welding are carried out respectively. The changes of microstructure and mechanical properties of each pass layer of welded joint were studied by means of SEM and tensile test. In order to better study the multi-layer and multi-pass welding of S620Q thick plate, the temperature field distribution of S620Q steel multilayer and multi-pass welding is obtained by using the ANSYS finite element software and double ellipsoid heat source model at the same time. The (HAZ) width of heat affected zone (HAZ) of each pass welding layer of thick plate is predicted. Based on the calculation of temperature field, the distribution of residual stress in welded joints is obtained by means of the thermal-structure indirect coupling method and the actual residual stress measurement. The welding experiments show that under the conditions of GMAW and FCAW, the main microstructure of solid core weld is acicular ferrite (AF) granular bainite (GB), fluid-core weld with a small amount of GB AF;. The average strength of the flux-cored joint weld is slightly higher than that of the solid core weld, and the hardness distribution level of the joint is higher than that of the solid core weld. When the heat input is small, the coarse crystal structure of solid core becomes LB, core, and ML, becomes ML,. With the increase of heat input, the coarse crystal zone structure of solid core changes into coarse LB, core into GB; core. The impact test shows that the impact value of the solid core weld is higher than that of the flux-cored weld, while the impact value of the core-fusion zone and coarse grain zone is slightly higher than that of the core-cored weld. Due to the secondary thermal cycling, the coarse grain boundary is irregular, island M-A and bainite are formed, the partial quenching zone grain boundary is GB, but the coarse grain area grain boundary is irregular, and the island M-A has little toughness damage. The distribution of temperature field and stress field of S620Q thick plate multilayer and multi-pass welding is obtained by numerical simulation, the variation law of thermal cycle curve of measured thermal cycle curve is the same as that of simulated calculation of HAZ, and the maximum error of maximum peak temperature is 14% compared with the measured value. The HAZ region width calculated by numerical simulation is basically consistent with the measured HAZ region width. The residual tensile stress after welding is mainly distributed in the weld seam and its adjacent area, the maximum equivalent residual tensile stress is 437 MPA / a, and the transverse residual tensile stress is 500MPa at the root of the X groove welding, and the displacement is 0.968mm in the thickness direction. The simulated residual stress curve is consistent with the measured value of thick plate. Through the analysis of GMAW and FCAW welding experiments and numerical simulation results of S620Q high strength thick plate, this paper provides a certain experimental basis for selecting appropriate welding method and technological parameters in actual welding of S620Q thick plate and improving the welding quality of high strength thick plate.
【學(xué)位授予單位】：內(nèi)蒙古科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG444.72

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