Effects of Workshop Fabrication Processes on the Deformation Capacity of S960 Ultra-high Strength Steel

Deformation of a direct quenched type of ultra-high strength steel (UHSS) with low-carbon content is studied in this work. Although this material, as manufactured, combines high strength and good ductility, it is highly sensitive to the workshop fabrication processes used. The presence of stress concentration due to structural discontinuity or notch effects can accentuate the effect of fabrication processes on the deformation capacity of the material. To evaluate the influence of fabrication methods on deformation capacity, a series of tensile tests are done on both pure base material (BM) and after the steel has been subjected to heat input (HI) or cold forming (CF). To study the effect of HI due to welding or other heat-based workshop fabrication processes, the surface of the material was dressed by laser beam at controlled speed and laser intensity. CF effects were studied by bending the specimens to a predetermined angle prior to subjecting the steel to tensile testing. Experimental results were compared with numerical simulation using LS-DYNA simulation software. The generated results show acceptable agreement between experimental and numerical simulation outcomes.