Gas metal arc welding of dissimilar AHSS sheets

• Dissimilar gas metal arc welding (GMAW) between TWIP and TRIP steels has been investigated.
• After a pilot experimentation, proper welding parameters have been set to obtain sound TWIP/TRIP joints.
• Microstructure, hardness, mechanical strength and failure mode describe joints quality and their mechanical performance.
• The fracture of the welded tensile samples always occurred within the fusion zone in a ductile manner.
• GMAW can be a solution to assemble car body parts made of TWIP and TRIP steels.

Gas metal arc welding (GMAW) is one of the most common methods used in the automotive industry to assemble car body parts of dissimilar high strength steels. Load bearing capacity of these components depends largely on the quality (e.g. absence of cracks, microstructure and mechanical strength) of weldments. In this context, GMAW, with the use of an austenitic steel filler, of a new advanced high strength TWIP sheet steel and a TRIP sheet steel is investigated in this research. Quality of butt weld beads being examined in terms of processing, microstructure, and mechanical properties. The grain coarsening and microstructural changes, as well as volumetric fraction of each phase, in the heat affected zone at the TWIP and TRIP side of the joint were also determined. The optimal heat input range needed to obtain good quality joints was determined, achieving ultimate tensile strengths over 585 MPa and fracture elongations over 9%.

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