水下高压干式GMAW电弧及熔滴过渡行为特征和机理研究

The underwater hyperbaric GMAW is a preferred, fast, economic,and reliable progress for pipeline repair. Due to the underwater high pressure ambient and the special atmosphere，the GMAW progress will become unstable gradually together with the environmental pressure increasing. This problem restricts appling the hyperbaric GMAW progress into practice. This project is planning to work on the following items: (1) Study on the charateristics and laws of the arc behavior and metal transfer of underwater hyperbaric GMAW progress in special pressure environment. (2) Simulate on the arc behavior and metal transger of underwater hyperbaric GMAW progress. (3) Discuss and search for the methods to enhance the stability of the arc and metal transfer in underwater hyperbaric GMAW progress. According to the above-mentioned study, the project intends to acquire the following results: One is to obtain the behavior charateristics and the evolving laws of the welding arc and transfer mode in underwater hyperbaric GMAW progress. The other is to confirm the key effects on the stability of arc and metal transfer , and to give the direction to enhance the welding stability of the underwater hyperbaric GMAW progress using the sensitivity weigh valueing method. Another is to achieve the optimized parameters for a stable underwater hyperbaric GMAW procedure. All the results make the basis of the underwater hyperbaric GMAW process for putting it into practice. The study will effectively promote our underwater pipeline repairing technology level,at the same time, has important practical meaning to ensure China's developing and transporting the maritime oil and gas safely.

水下高压干式GMAW焊接是快速、经济且质量可靠的水下管道修复的优选方法。在水下高压干式环境中，随环境压力增加焊接过程逐渐趋于不稳定，从而限制了GMAW方法实际应用。本研究模拟水下高压干式环境开展如下研究工作：（1）多因素作用的水下高压干式GMAW电弧及熔滴过渡行为；（2）多场耦合的水下高压干式GMAW电弧及熔滴过渡机理的数值模拟及试验验证；（3）水下高压干式GMAW电弧及熔滴过渡稳定性的调控方法。通过上述研究，以揭示水下高压环境下GMAW焊接电弧及熔滴过渡的行为特征及演变规律，利用敏感权重方法确定影响电弧及熔滴过渡稳定性的关键因素，给出水下高压干式GMAW焊接稳定性的改进方向，获得稳定的水下高压干式GMAW焊接新工艺，为水下高压GMAW焊接实际工程应用提供理论和基础数据。该研究将有效促进我国水下管道修复技术水平的提升，对保障我国海洋油气资源开发及运输安全具有重要的现实意义。

水下高压干式GMAW焊接是快速、经济且质量可靠的水下管道修复的优选方法。在水下高压干式环境中，随环境压力增加焊接过程逐渐趋于不稳定，限制了GMAW方法实际应用。本研究通过实验与数值模拟相结合的方法开展研究工作：（1）进行了多因素作用的水下高压干式GMAW电弧及熔滴过渡行为特征研究，获得了环境压力、焊接电流和电弧电压、保护气体、焊丝伸出长度等主要因素对水下高压干式环境下GMAW电弧、熔滴过渡行为的作用规律；（2）建立了水下高压干式GMAW电弧及熔滴过渡数值模型，分析了不同压力环境下电弧温度分布及特征、焊接熔滴过渡的动态行为，进一步探索了各主要因素对电弧及熔滴过渡影响的变化规律，并与试验结果相验证；（3）探索了提高水下高压干式GMAW电弧及熔滴过渡稳定性的新措施和新方法。通过上述研究，揭示水下高压环境下GMAW焊接电弧及熔滴过渡的行为特征及演变规律，利用敏感权重方法确定影响电弧及熔滴过渡稳定性的关键因素，分别从提高电弧能量和电弧挺度等方面给出水下高压干式GMAW焊接稳定性的改进方向，即通过改变电源极性、提高电弧能量等措施或采用脉冲焊接方法和CMT焊接方法，可以改善水下高压干式GMAW焊接过程不稳定问题，为水下高压GMAW焊接实际工程应用提供理论和基础数据。

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