Study On Welding Process Of Stainless Steel Vacuum Vessels

Production of stainless steel vacuum vessels generally encountered high rate of product defects. This paper tested a number of samples, analyzed their production process, and determined the location of welding defects, a welding fixture was designed, welding parameters were adjusted, the quality of welding was improvedA number of insulation cup samples were tested by leak detection with compressed air, the results showed that the leak site mostly distributed in the edge weld seam position and sealing position of the tail brass at the bottom of the insulation cup, the main welding defects were weld beading, burning through and incomplete fusion, the main causes of welding defects are welding alignment deviation and the unsuitable welding parameters in welding process.The main causes of weld misalignment for mechanized welding process, are coaxial deviation, end jump and roundness deviation of the cups; an automatic TIG welding fixture was designed fixed program of automatic adjustment and flexible connection, the position of the insulation cup can be automatically adjusted, welding alignment deviation can be controlled within0.2mm; the applicability, stability and manufacturing cost control of the fixture achieved the expected goals.Welding parameters were optimized by experiment, the optimal welding current is20-22A, and the optimal welding speed is550-600mm/min for the welding with the welding fixture.With the welding fixture and suitable welding parameters, high quality weld can be obtained, the appearance of the weld was smooth, the melting depth was uniform, there were no obvious welding defects, the weld is compact and the weld microstructure is small austenite and a small amount of ferrite, qualified rate of the weld ban be close to100%in experimental conditions...