In this research, it is aimed to investigate the effect of different shielding gas compositions and different welding speeds on the welding quality in MAG (Metal Active Gas) welding of S355J2+N structural steel. Welding process was carried out with semi-automatic welding mechanism designed for the welding process. 27 welded parts were obtained by using 9 gas mixtures and 3 speed values for welding processes. Various combinations of Ar (Argon), O2 (Oxygen), CO2 (Carbon Dioxide) gases were used as a shielding gas mixture. Amount of O2 in Ar was kept constant and the amount of CO2 was changed in the triple gas compositions. And then amount of CO2 in Ar was kept constant and the amount of O2 was changed. Flow rate of the gas mixtures was set at 12 lt/min and the wire feed speed was 4.9 m/min for the welding process. Welding speed values in the semi-automatic welding mechanism were chosen as 10 cm/min, 15 cm/min and 22.5 cm/min. Impact strength values of the welded parts were measured by performing Charpy V-notch impact tests. As a result of this study, changes in the impact strength value were observed as the amount of CO2 increased while the O2 in the shielding gas was constant, or as the amount of O2 increased while the CO2 in the shielding gas was constant. It was determined that as the welding speed increased, the toughness value decreased.
Anahtar Kelimeler: Mag Welding, S355 Structural Steel, Shielding Gas Mixture, Automatic Welding
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