Investigation of interior structure and mechanical properties of AISI 316 L austenitic stainless steel sheets joint with arc welding

In this study, the effect of the shielding gas type used in 6 mm thick AISI 316L austenitic stainless-steel plates combined with non-melting Tungsten Inert Gas (TIG) and Metal Inert Gas (MIG) welding methods and the welding current values applied in the passes on the micro-macro structure and strength of the weld seam are discussed. Shielding gas parameters were selected as 100% Argon (Ar), 97.5% Ar + 2.5% CO2 and Mix-212 (84% Ar, 12% CO2 and 4% O2) and three different heat inputs were applied under each shielding gas. It has been observed that the use of 97.5% Ar + 2.5% CO2 gas in the MIG welding method increases the tensile strength in the tensile test. In the micro-hardness studies of the samples, it was observed that the hardness in the weld zone was generally at a balanced level in all samples. It was observed that the highest hardness value was obtained by MIG welding method with 97.5% Ar + 2.5% CO2 gas with high ampere. It has been observed that the grains in the ITAB region progressed from the source area towards the base metal (unwelded region) side in accordance with the cooling morphology, and the grains with more clear boundaries and smaller size than the ITAB region were formed in the region of origin. It was observed that the highest tensile strength belonged to the plate with the MIG welding method medium amperage value.