窄间隙双缆式GMAW熔池流体行为研究

发布时间：2018-05-17 12:48

本文选题：双丝气保焊 + 缆式焊丝　；参考：《江苏科技大学》2017年硕士论文

【摘要】：近年来,在海洋工程、油气管道、压力容器及船舶制造等行业中焊接工作量有了大幅度的增加,传统焊接方法难以满足日益增加的焊接生产需求。在保证焊接质量的前提下,提高焊接生产效率成为了焊接工作者的主要研究方向,本文研究的窄间隙双缆式GMAW焊接技术就是在这种大环境下发展起来的。本研究主要研究Q235钢厚板的双缆式GMAW焊接,以缆式焊丝作为填充材料,用GAMBIT软件建立合适的数学模型,基于FLUENT和UDF的二次开发,考虑相变潜热、材料热物理性能等问题,对双缆式GMAW堆焊和窄间隙双缆式GMAW焊熔池温度场及流场进行模拟计算。为了验证所建模型的准确性,分别采用红外热像仪测温和焊缝宏观金相验证了模拟仿真结果,对模拟结果进行了试验验证。建立了双缆式GMAW焊三维数值模型,对双缆式GMAW焊熔池温度场和流场的演变过程进行了模拟计算。研究结果表明,随着焊接过程的进行,熔池逐渐长大,熔池内部温度逐渐升高,并且流动加剧,温度场和流场分布范围随之增大,熔池前端等温线分布较为密集,温度梯度大,熔池后端等温线分布较为稀疏,温度梯度较小。并将模拟结果与普通单丝气保焊的熔池温度场及流场进行对比分析,和传统单丝气保焊相比,双缆式GMAW焊具有加热范围大、保温时间长、熔敷速度快等特点,能够有效解决传统单丝气保焊加热过于集中、焊接熔池过热、熔敷效率低等问题。研究不同焊接工艺参数对双缆式GMAW焊接过程中熔池温度场和流场的影响。研究表明,在其它焊接参数保持不变的前提下,熔池温度场和流场分布范围随着焊接电流的增大而增大,熔池最高温度和最大流速也随着焊接电流的增大而增大,总电流为400A、500A和600A时熔池最高温度分别为2377K、2514K和2726K,熔池最大流速分别为9.1cm/s、10.3cm/s和12.6cm/s;当焊接速度不断增加时,熔池温度场和流场分布范围则随之减小,熔池内部最高温度和最大流速也随之减小,焊接速度为600mm/min、900mm/min和1200mm/min时熔池最高温度分别为2810K、2726K和2569K,熔池最大流速分别为13.9cm/s、12.6cm/s和11.5cm/s。研究了不同前后丝电流下的焊接熔池温度场及流场,对比得出较大的前丝电流有利于焊缝的铺展。研究不同焊接工艺参数对窄间隙双缆式GMAW焊接过程中熔池温度场和流场的影响,其变化规律和双缆式GMAW焊的变化规律基本相同。随着间隙的增大,熔池温度场和流场分布范围随之减小,最高温度和最大流速也随之减小,间隙为14mm、16mm和18mm下熔池最高温度分别为3219K、3134K和3022K,熔池最大流速分别为14.1cm/s、13.4cm/s和12.6cm/s;随着双丝间距的增大,熔池温度场和流场分布范围随之减小,最高温度随之增大,最大流速随之减小,双丝间距间距为10mm、15mm和20mm下熔池最高温度分别为3134K、3209K和3279K,熔池最大流速分别为13.4cm/s、12.6cm/s和11.7cm/s;随着双丝偏移量的增加,熔池温度场分布范围减小,最高温度也随之减小,双丝偏移间距为0mm、2mm和4mm下熔池最高温度分别为3134K、2997K和2904K。研究了脉冲电流下的窄间隙双缆式GMAW焊熔池温度场和流场分布规律,得出一脉冲加一普通电流为最佳组合。验证了模拟结果的准确性,证明了本研究所建计算模型的可靠性。
[Abstract]:In recent years, the workload of welding in marine engineering, oil and gas pipeline, pressure vessel and shipbuilding industry has been greatly increased. The traditional welding method is difficult to meet the increasing demand of welding production. In the premise of ensuring the quality of welding, the improvement of welding production efficiency is the main research direction of the welding workers. The narrow gap double cable GMAW welding technology is developed in this big environment. This study mainly studies the double cable type GMAW welding of the thick Q235 steel plate. The cable type welding wire is used as filling material and the GAMBIT software is used to establish the appropriate mathematical model. Based on the two development of FLUENT and UDF, the latent heat of phase change and the thermal physical properties of the material are considered. The temperature field and flow field of double cable type GMAW surfacing and narrow gap double cable type GMAW welding pool are simulated. In order to verify the accuracy of the model, the simulation results are verified by infrared thermograph temperature measurement and weld macroscopic metallography, and the simulation results are verified. A three dimensional numerical model of double cable type GMAW welding is established. The temperature field and the evolution process of the flow field of the cable type GMAW weld pool are simulated. The results show that, with the process of welding, the molten pool grows up gradually, the temperature in the molten pool increases gradually, and the flow is intensified. The distribution range of temperature field and flow field increases, the distribution of the isothermal line in the front end of the molten pool is more dense, the temperature gradient is large and the molten pool is after the pool. The distribution of the end isotherm is relatively sparse and the temperature gradient is small. Compared the simulation results with the temperature field and flow field of the weld pool of ordinary monofilament welding, compared with the traditional monofilament gas shielded welding, the double cable GMAW welding has a large heating range, long heat preservation time and fast melting speed, which can effectively solve the traditional monofilament welding heat welding heating too much. The influence of different welding parameters on the temperature field and flow field of the molten pool during the double cable GMAW welding process is studied. The study shows that the temperature field and the flow field distribution of the molten pool increase with the increase of the welding current, and the highest temperature of the pool and the maximum temperature of the molten pool. The maximum flow velocity increases with the increase of welding current, the total current is 400A, the maximum temperature of the pool is 2377K, 2514K and 2726K at 500A and 600A. The maximum flow velocity of the pool is 9.1cm/s, 10.3cm/s and 12.6cm/s respectively. When the welding speed is increasing, the temperature field and the distribution range of the flow field are reduced, and the highest temperature and the most temperature in the molten pool are found. The maximum flow velocity also decreases with the welding speed of 600mm/min, 900mm/min and 1200mm/min, the maximum temperature of the pool is 2810K, 2726K and 2569K respectively. The maximum flow velocity of the molten pool is 13.9cm/s, 12.6cm/s and 11.5cm/s. respectively, and the welding pool temperature field and flow field under different wire current are studied, and the comparison shows that the larger front wire current is beneficial to the weld. The influence of different welding parameters on the temperature field and flow field of the weld pool during the narrow gap double cable GMAW welding process is studied. The variation law of the weld pool and the double cable type GMAW welding are basically the same. With the increase of the gap, the temperature field and the distribution range of the flow field decrease, the maximum temperature and the maximum flow velocity also decrease, the gap is 14mm, 1 The maximum temperature of molten pool in 6mm and 18mm is 3219K, 3134K and 3022K respectively, and the maximum flow velocity of molten pool is 14.1cm/s, 13.4cm/s and 12.6cm/s, respectively. With the increase of double wire spacing, the temperature field and the distribution range of flow field decrease, the maximum temperature increases, the maximum velocity decreases, the distance between the two wires is 10mm, and the molten pool in 15mm and 20mm is the most high temperature. The maximum flow velocity of the molten pool is 13.4cm/s, 12.6cm/s and 11.7cm/s, respectively 3134K, 3209K and 3279K. With the increase of the double wire offset, the distribution range of the melting pool temperature field decreases, the maximum temperature decreases, the offset distance of the double wire is 0mm, the maximum temperature of the molten pool under 2mm and 4mm is 3134K, 2997K and 2904K. have studied the narrow gap between the pulse current. The temperature field and the distribution of the flow field in the weld pool of double cable type GMAW welding are obtained. The optimum combination of a pulse plus a common current is obtained. The accuracy of the simulation results is verified, and the reliability of the calculated model is proved.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.11

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