| As a high efficient welding technology,one-side welding has been widely used in the manufacture of ship,bridge,pressure vessel and a variety of large steel structure and equipment. Compared with double welding, it can significantly improve production efficiency, improve the working environment,reduces the labor intensity of workers, improve the welding quality.It has very significant economic and social benefits. At present, our country especially in Tangshan area, welding method of small pressure vessel is mainly CO2 gas shielded arc welding. The method has the advantages of high productivity, small welding deformation, high cost performance, easy to operate. But the CO2 gas shielded arc welding has many shortcomings, such as poor welding seam smoothness, spatter,gas hole, so it is difficult to realize one-side welding with back formation.Protective component and ratio of gas directly influence the properties of welding arc welding process, determine the formation of weld,process stability and properties of welded joints. Metal Active Gas Arc Welding(MAG) eliminates the disadvantages of CO2 gas shielded arc welding.It can improve the welding quality and achieve one-side welding with back formation.This paper aimed at welding conditions in the small pressure vessel industry, starting from the basic theory of Metal Active Gas Arc Welding in one-side welding with back formation, Analysed the effects of shielding gas in welding process stability, formation of weld, the weld mechanical properties for small pressure vessel; Experiments were made to study ceramic liner MAG one-side welding; Through the cost comparison of CO2 gas shielded arc welding and MAG, it analysed the feasibility of MAG one-side welding with back formation for pressure vessel. In the end,using ceramic liner MAG one-side welding process, the triers produced some small pressure vessels. The actual application shows that the ceramic liner MAG(20%CO2+80%Ar) can be used to weld small pressure vessel. The results of the process evaluation is good welding seam, no undercut, porosity or other defects. various tests such as the tensile test, bending test, impact test, the appearance and ray detection have proved that welding quality can meet requirements.This paper provides a reliable technical guarantee about welding process of one-side welding with back formation for the small pressure vessel. Ceramic liner MAG welding technology in one-side welding with back formation is applied to small pressure vessel. welding joint performance is better than that of CO2 gas shielded arc welding. It is worthy of popularization and application. |
