Caracterização da junta dissimilar em solda de materiais do tipo estrutural e ARBL

Abstract

This study aims to evaluate the effects of two different filler metals in mechanical properties and microstructure of a weld dissimilar formed by fine-grained structural steel ASTM A36 and structural steel HSLA (High Strength Low Alloy) S700MC. The materials were joined by the welding process to electric arc with shielding gas, known as GMAW (Gas Metal Arc Welding). As filler metal were used welding solid wire AWS ER 70S-6, for making the welded joint 1 (JS1), and AWS ER 80S-D2, for making the welded joint 2 (JS2). Both joints were welded with the same parameters of pulsed current in welding and robotic welding cell laboratory at UPF. Microstructural characterization of joints was performed using metallographic test (and macrography micrograph) and mechanical characterization of joints made to slant the Vickers microhardness profile, tensile test and fatigue test on a work critical voltage. The fractographic analysis of fatigued specimens gave up through scanning electron microscopy. The evaluation of the test results allowed out in JS1 including silicon (Si) and manganese (Mn) in the connection zone (ZL) of the filler metal (MA) with base metals (MB). Both together behaved similarly in the tensile test, breaking up in nearby voltages to 485 MPa in base metal ASTM A36. In the hardness test, the JS2 presented significantly higher values. In micrographs, there is the presence of Widmanstätten ferrite in the heat affected zone by heat (HAZ) of MB ASTM A36, where there was a fracture of the specimens in tensile tests. Regarding the fatigue test, the JS1 showed superior behavior to JS2. The fracture mechanism analysis in both welded joints predominant ductile rupture characterized by coalescence of wells (dimples). Thus, the use of different filler metals influenced more significantly as regards the mechanical behavior of the joints, especially the higher fatigue life of JS1.