| Abstract Scope |
The introduction of advanced high-strength steels in the automotive industry has sparked renewed interest in resistance welding research, aiming to reduce vehicle weight and improve fuel efficiency. Understanding the weldability of these new materials to optimize process parameters for better weld strength is crucial. Various standards from different regions and complexities govern this type of welding. Among them, a set of standards was selected to enable the choice of parameters, electrodes, machine preparation, and analysis of welded joint quality. Initially, the machine used must comply with standards and specifications established in ISO-669 concerning electrical and mechanical characteristics. Electrode selection must meet hardness and load requirements according to ISO-5821:2009 and ISO-18278-1:2015 standards to prevent plastic deformation, especially for high-strength steels requiring higher welding forces. Electrode alignment should follow ISO-18278-2:2016(E) to ensure parallelism and centering. Its geometry is extensively discussed in literature and recommended by ISO-18278-2:2016(E) and AWS-C1.1M 2019 standards, where the electrode contact area diameter is a fundamental factor in the size of the imprint left on the material, as well as the weld nugget. For coated or galvanized sheets, longer welding times and more pulses are recommended, depending on the sheet thickness, primarily to avoid zinc inclusion in the welded joint, as recommended in literature and AWS-C1.1M:2019, ISO-5182:2008, and ISO-18278-2:2016(E) standards. Maximum indentation and minimum weld nugget diameter are defined by AWS D8.1:2021. For high-strength steels, more conservative criteria for minimum weld nugget diameter are recommended according to AWS-C1.1M:2019. Metallographic and mechanical tests for pullout and shear, as described in ISO-14270:2016, ISO-14273:2016, ISO-14272:2016, and AWS-C1.1M:2019 are essential to assess the quality of the welded joint and its failure modes. Additional analyses via SEM and chemical analysis may also be conducted. |