Influence of Heat Input on the Characteristics and Properties of AISI 316 and AISI 316L Steels Weld Beads

Abstract

AISI 316 and AISI 316L steels have wide industrial application, so the importance of evaluating the weldability of these alloys. In this study, comparative analysis was made between the samples of both welded steels with heat inputs of 0.5, 1.5 and 2.5 kJ/mm using autogenous TIG process. The variation of heat input on weld bead morphology, the spacing between δ ferrite bands, the volumetric fraction of ferrite δ and the microhardness in the molted zone were analyzed. The results showed that the dimensions of the welding metal, the spacing between ferrite bands and the volumetric fraction of ferrite δ become larger with the increase of the heat input. The welded samples of AISI 316L steel presented larger ferrite band spacing and larger δ ferrite fractions than AISI 316 steel. As for microhardness, the study showed that the closer to the center of the molted zone, the greater the microhardness value and the hardness of AISI 316 steel higher than that of AISI 316L steel. Through computational modeling it was possible to evaluate the temperature distribution along the welded plates and compare the thermal cycle obtained by simulation with the experimentally calculated cycle for the input of 0.5 kJ/mm.

Key-words:
Austenitic stainless steels; Weldability; Autogenous TIG Process; Computational modeling