Characterizing and optimizing bondline reactions during electric resistance welding of advanced high strength steels

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To improve passenger safety and vehicle fuel economy, automotive companies are increasing use of both advanced high strength steels (AHSS) and adopting hydroformed tubular construction for automotive body-in-white. However, successful use new AHSS in tubular design requires successful electric resistance welding (ERW) of these grades. The high C, Si and Mn, and Al of new AHSS leads to bondline decarburization the formation of non-metallic particles that degrade bondline strength.The proposed project will understand ERW weld defects using both an industrial and laboratory approach. Industrial trials will be conducted to determine how welding parameters affect non-metallic formation and bondline decarburization. Then kinetics of non-metallic formation will be measured using thermal analysis. Using both industrial and lab data, new processing parameters will be designed to optimize bondline properties. The effectivity of these parameter will be tested using thermomechanical simulation. Successful parameters will be trialed on ArcelorMittal Dofasco's (AMD) tube mill.This project will i) characterize the kinetics of Mn, Si, and Al non-metallic formation, ii) develop a model for formation of non-metallics in the ERW process; iii) characterize how welding temperature and upset lead to bondline decarburization; iv) develop a cost-effective off-line technique to simulate production tubing; and v) develop robust ERW parameters to optimize weld properties in new AHSS. The know-how developed from this project will contribute to the competitiveness of Canada's steel industry, allowing Canadian tube producers to participate in a 49,000 T market. The advanced tubes will supply automotive parts suppliers, many of whom are Canadian based. Integration of these parts in to automotive designs have the potential to reduce vehicle greenhouse gas emissions (GHG) by 1.5 T over the vehicle life, cumulating to 3 MT for all vehicles sold across Canada; 1.5% of Canada's 2030 GHG reduction targets.