Influence of shielding gas variation and welding parameters on the microstructure and microhardness of SAE 1035 steel welded by the MAG process

Abstract

The objective of this work was to evaluate the effect of changing the parameters of voltage, electric current and gases on the microstructure and microhardness of SAE 1035 steel. The welding process applied to the samples was the MILF STELL-MAG mode in the 4G position. The metallographic preparation was performed, following the ASTM E3 standard. The microstructural observations of each region of the welded joint were carried out in an optical microscope (THS – 200 Olympus) and for microhardness analysis a microhardness tester (HM-100 Mitutoyo) was used with a load of 1.0 kgf. ASTM E384 – 11 both carried out at the Science and Materials Engineering Laboratory of the State University of Amazonas (UEA). For sample 1, 170 ± 30A and 100% CO2 were used, for sample 2, 175 ± 30A and 100% CO2 were used, for sample 3, 180 ± 30A and 100% CO2 were used, for sample 4, 190 ± 30A and 100%CO2 and for sample 5 230 ± 30A and 100% Ar were used. By the microhardness analysis it was observed that there is an increase in the HAZ with the increase of the current using the CO2 gas. Welding using Argon gas showed a reduction in the microhardness of the HAZ. It is observed that there was an increase in the pearlite colony of the base metal close to the HAZ with the increase of the electric current. There was an increase in the HAZ with increasing electrical current.