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Abstract
Galvannealed high strength low alloy steel 350 (GA HSLA 350), because of its high strength-to-weight ratio, is particularly attractive in transportation applications. The GA HSLA 350 steel was spot welded at different welding currents to identify a suitable welding current giving good spot welds. Failure loads in the tensile shear increased with increasing welding current. There was a concomitant increase in the nugget diameter and the failure mode changed from interfacial fracture to button pull-out failure. Cross tension and microhardness tests were also carried out. The fusion zone microstructure was martensitic with a microhardness that was twice that of the base metal.
Galvannealed high strength low alloy steel 350 (GA HSLA 350), because of its high strength-to-weight ratio, is particularly attractive in transportation applications. The GA HSLA 350 steel was spot welded at different welding currents to identify a suitable welding current giving good spot welds. Failure loads in the tensile shear increased with increasing welding current. There was a concomitant increase in the nugget diameter and the failure mode changed from interfacial fracture to button pull-out failure. Cross tension and microhardness tests were also carried out. The fusion zone microstructure was martensitic with a microhardness that was twice that of the base metal.
L'acier 350, à haute résistance et faiblement allié, recuit par galvanisation (GAHSLA350), est particulièrement intéressant pour les applications en transport grâce à son rapport résistance-poids élevé. On a soudé par points l'acier GA HSLA 350 à différents courants de soudage pour identifier un courant de soudage adéquat produisant de bonnes soudures par points. Les charges de rupture en cisaillement sous traction augmentaient avec l'augmentation du courant de soudage. Il y avait une augmentation concomitante du diamètre du noyau et le mode de rupture changeait de rupture interfaciale à rupture par arrachement du bouton. On a également effectué des essais de traction et de microdureté. La microstructure de la zone de fusion était martensitique avec une microdureté qui était deux fois celle du métal de base.
