S620Q高强厚板焊接过程数值模拟及实验研究
发布时间：2019-01-10 11:50
【摘要】：S620Q厚板低碳调质钢广泛应用于机械、矿山等领域，焊接作为其应用中最主要的连接方式，焊接性能直接关系到设备构件的安全可靠运行。近年来，运用实验研究和数值模拟相结合的方法研究厚板的焊接性能日益受到关注。因此本文通过对40mm厚S620Q高强厚板分别进行实芯焊丝气体保护焊（GMAW）和药芯焊丝气体保护焊（FCAW）焊接实验，利用扫描电镜及拉伸试验等分析手段研究了焊接接头各道焊层的组织转变和力学性能变化规律。为了更好的研究S620Q厚板多层多道焊接，本文同时运用ANSYS有限元软件采用双椭球热源模型得到S620Q钢多层多道焊接温度场分布规律，并对厚板各道焊层热影响区（HAZ）宽度进行了预测。在温度场计算的基础上，，通过热－结构间接耦合法与实际残余应力测试，得出焊接接头残余应力的分布规律。 焊接实验表明， GMAW和FCAW工艺条件下，实芯焊缝主要组织为针状铁素体(AF)+粒状贝氏体(GB)，药芯焊缝组织为GB+少量AF；药芯接头焊缝的平均强度略高于实芯焊缝，而且接头硬度分布水平高于实芯焊缝。热输入较小时，实芯粗晶区组织为LB，药芯为ML，随着热输入的增大，实芯粗晶区组织转变为粗大LB，药芯转变为GB；冲击试验表明，实芯焊缝冲击值高于药芯焊缝，而药芯熔合区、粗晶区冲击值略高于实芯粗晶区。受到二次热循环作用，粗晶区晶界处生成了不规则、岛状M-A和贝氏体，部分淬火区晶界处为GB，但粗晶区晶界处不规则、岛状M-A对韧性损害较小。 通过数值模拟得到了S620Q厚板多层多道焊接温度场和应力场分布规律；实测热循环曲线与模拟计算HAZ的热循环曲线变化规律相同，最高峰值温度与实测值相比，最大误差为14%；数值模拟计算的HAZ各区域宽度与实际测得的HAZ各区域宽度基本吻合。厚板焊后残余拉应力主要分布在焊缝及其附近区域，最大等效残余拉应力为437MPa，X形坡口焊根处具有较大横向残余拉应力为500MPa；厚度方向上发生位移量为0.968mm的面外角变形；模拟残余应力曲线与厚板实测值变化趋势一致。 通过对S620Q高强厚板的GMAW和FCAW焊接实验及数值模拟结果进行分析研究，为S620Q厚板在实际焊接中选择合适的焊接方法及工艺参数，改善高强厚板的焊接质量，提供一定的实验依据。
[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.
【学位授予单位】：内蒙古科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG444.72
本文编号：2406271
[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.
【学位授予单位】：内蒙古科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG444.72
【参考文献】
相关期刊论文 前3条
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2 鹿安理,史清宇,赵海燕,吴爱萍;厚板焊接过程温度场、应力场的三维有限元数值模拟[J];中国机械工程;2001年02期
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