Undersökning av svetsegenskaper för svetsning med rörtråd kontra homogen tråd
WeldingMicrostructureFatigueTensile testingImpact testingMIG/MAGSvetsteknikMikrostrukturUtmattningDragprovSlagprovMIG/MAG
Welding is a common method for joining of metal or plastic construction parts. This report describes several different weld methods in general terms. The report focuses on the GMAW method, specifically MAG welding.A case study has also been performed for the company Wenmec. The task received from the company was to compare the mechanical properties of joints welded with the tube electrode called Nittetsu SM-3A and joints welded with the homogenous electrode called ESAB Aristorod 12.63. Both types of weld joint were welded with the MAG method with an Argon based shielding gas with 18% CO2. The final task of this study is to compare the cost of these electrodes and then help Wenmec to decide which electrode that is the most cost effective.Tensile testing, impact testing and fatigue testing were performed on the weld joint samples. The hardnesses, microstructures, failure zones and chemical composition were examined with optical microscopy and SEM.The weld time, the amount of consumed electrode and the weld energy was measured during welding. These properties were similar and the differences between the different joints could be ignored.Both weld joint types showed similar microstructures and hardnesses. The microstructure was ferrite with carbides or perlite at the grain boundaries. Some silicon oxides were found in the grains.The yield strength, ultimate tensile strength and cycles to fatigue failure were similar in the two joint types, but the Aristorod weld joint showed higher impact strength and elongation at break.The chemical composition showed that the SM-3A electrode was a metal cored electrode with some additions of deoxidizing elements and a Copper coating. The Aristorod 12.63 electrode also showed the presence of deoxidizing elements and likely had a Titanium based coating. The sheet metal used as the work pieces are called Ruukki Laser 355 MC and is steel with low Carbon content, some Manganese and some impurities.The SM-3A electrode was costlier than the 12.63 electrode. This work concluded that the 12.63 electrode was a better alternative for Wenmec due to the lower cost, higher impact strength and higher elongation at break