A Study on Micro Tig Tube Welding of Thin Extra Aisi 321 Austenitic Stainless Steel Sheets

Abstract

Exhaust gas recirculation tubes were used for this study. To make bellows shape from TIG (Tungsten Inert Gas) welded extra thin tubes hydraulic forming method is used in industry. For this study, 0.2 mm thick AISI 321 austenitic sheets were combined by using micro TIG welding method and 11.80 mm in diameter pipes were produced. For the TIG welding process of thin sheet tubes shaped by liquid pressure precise welding parameter adjustment is required. With the micro TIG arc welding technique, healthy weld seams were obtained in three different power parameters. The effects of this differences on the mechanical properties and microstructure of the weld joints were experimentally investigated. The welding speed was kept constant and three different welding current and voltage values were selected. The images of the weld zone of the samples were taken by an optical microscope. The microstructures formed in the weld zone were examined. Micro hardness values of the base metal, HAZ (Heat Affected Zone) and weld zone were evaluated. Tensile tests of the samples were carried out for three different parameters. Strength of welding seams is very important in the hydroforming process. In order to evaluate the strength of the joint, the welded tube elastomer expansion test was applied. The effect of the expanding tube wall on the welded joint was evaluated by the expansion test. As a consequence of the study, the optimum power parameters of the welded joint was determined by destructive and non-destructive tests.

Keywords

• TIG welding,EGR tubes,Elastomer expansion test

References

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