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采用CMT焊接方法,在模拟水下高压环境的实验系统中分别进行了常压环境下(0.1 MPa)和环境压力为0.5 MPa下的焊接实验,实验中采用API X65管线钢接头为研究对象.焊接过程中采用高速摄像观察焊接电弧行为,2种环境压力下焊接过程均稳定,但与常压环境相比较,0.5 MPa环境压力下的CMT焊接电弧产生收缩,熔滴过渡频次降低.焊后对焊缝分别取样进行力学性能检测和金相组织观察,高压环境下焊缝及热影响区的金相组织因为环境冷却作用增强而出现上贝氏体组织,拉伸性能没有明显变化,低温冲击韧性下降,但测试数据也远高于相关标准要求.结果表明,CMT焊接方法改善了高压焊接过程的稳定性,满足水下高压干式焊接作业要求.
The CMT welding method was used to test the welding under the atmospheric pressure (0.1 MPa) and the ambient pressure (0.5 MPa) in the experimental system simulating the underwater high pressure environment, and the experiment was conducted using the API X65 pipeline steel joint as the research object. During the process, the welding arc behavior was observed by high-speed camera, and the welding process was stable under the two kinds of environmental pressures. However, compared with the normal pressure environment, the CMT welding arc shrinks at 0.5 MPa ambient pressure and the droplet transfer frequency decreases. The microstructure of the weld and heat-affected zone in the high pressure environment was bainite because of the cooling effect of the environment. The tensile properties did not change obviously and the low temperature impact toughness decreased , But the test data is also much higher than the relevant standards.The results show that the CMT welding method improves the stability of high pressure welding process and meets the requirements of underwater high pressure dry welding operation.