Optimization Of Hyperbaric Pulsed Gmaw Parameters And Influence On Surfacing Layers Corrosion Resistance

Underwater welding technology plays an important role in maintenance of submarine pipelines and offshore platforms.Hyperbaric welding can eliminate the influence of water on welding process,it has higher quality and more wide application than the wet underwater welding.Because seawater is a very strong electrolyte,so corrosion performance and service life of weld seam under underwater environment should also be considered except mechanical properties.In this paper,hyperbaric welding tests of Q345 steel were carried out.Effects of environmental pressure,process parameters and protective gas ratio on the corrosion resistance of the surfacing layer were investigated by electrochemical experiments and microstructure.In this paper,the influence of different pressures on the corrosion performance of the surfacing layer was studied.In the hyperbaric welding test chamber,surfacing layers were produced on Q345 steel plate under pressures from 0.1MPa to 0.7MPa,and were subjected to electrochemical experiment and microstructure metallographic observation.With the increase of environmental pressure,the corrosion resistance of the surfacing layer decreases,the grain size of the microstructure increases,and the density decreases.In this paper,the effects of different welding process parameters and shielding gas ratios on the corrosion performance of the surfacing layer were studied.In the hyperbaric welding test chamber,surfacing layers were produced on Q345 steel plate under pressures of 0.3MPa,0.5MPa,and 0.7MPa,and were subjected to electrochemical experiment and microstructure metallographic observation.With the increase of welding voltage,pulse peak current,or pulse frequency,the corrosion resistance of the surfacing layer increases,and microstructure uniformity and compactness also are improved.As the content of CO2 in the shielding gas increases from 0 to 15%,the anticorrosion performance of the surfacing layer is gradually improved,but will be weakened when CO2 content is further increased to 20%.