COLD-WIRE GMAW FOR AUTOMOTIVE APPLICATIONS

The use of dual phase (DP) high strength steel by automakers aims to reduce vehicle weight, which helps to decrease the fuel consumption and consequently CO2 emissions. Nowadays, most automotive welds are made using spot and/ or laser welding; however, many applications still demand arc welding processes to reduce cost and increase productivity. In this work the feasibility of using cold wire gas metal arc welding process (CW-GMAW) for joining of DP steel lap joints were investigated. DP600 steel lap joints were welded using both standard gas metal arc welding (GMAW) and CW-GMAW processes. Arc stability was evaluated, and the joints were compared in terms of distortion, microstructure, and microhardness. Results indicate that standard GMAW welds are more prone to porosity and exhibit higher distortion when compared with CW-GMAW, since the arc is established between the electrode and the plate in the GMAW. Meanwhile in CW-GMAW it is established between the electrode and the cold wire. This difference in arc attachment location and deposition rate in CW-GMAW welds leads to lower dilution when compared to standard GMAW specimens, and accounts for differences in microhardness profiles.