Effect of welding parameters on the microstructure and mechanical behavior of dissimilar AISI 304/AISI 430 thin plates welded by gas Tungsten arc welding

Abstract

In this work, the microstructure and mechanical behavior of dissimilar AISI 430 and AISI 304 thin sheets welded by Gas Tungsten Arc Welding using AISI 304 and AISI 316L as filler metals were studied. The obtained joints were characterized by optical and scanning electronic microscopy, Energy-dispersive X-ray spectroscopy and fluorescence, tensile tests and the Vickers microhardness test. Measurements carried out by energy dispersion X-ray spectrometry in the melting zone indicated a slightly heterogeneous distribution of nickel and iron. It was observed that the beginning of solidification of the zone fusion occurred through epitaxial growth. The WM solidification morphology was basically cellular influenced by temperature gradient, solidification rate and chemical composition. Variations in chemical composition and solidification morphology did not significantly alter the Vickers microhardness values in the melting zone. Results obtained in tensile tests indicated adequate mechanical behavior for the joints using AISI 304 as filler rod; those exhibited a ductile fracture behavior with the presence of dimples. However, the AISI 316L joints failure prematurely resulting in a fragile behavior.