Experimental Determination of Tensile Properties of an Ultra-High-Strength Structural Steel Alloy via Uniaxial Tensile Testing

This report experimentally characterizes the mechanical and plastic yield behavior of an ultra-high-strength steel alloy under uniaxial tensile testing. The experiment was carried out at room temperature using a universal testing machine, with load values recorded as a function of displacement. The resulting force–displacement curve was used to derive engineering stress–strain and true stress–strain curves using the relevant constitutive equations. The localized reduction in cross-sectional area due to specimen necking led to an inaccurate evaluation of the true stress values beyond the point of ultimate tensile strength. This discrepancy was corrected by implementing the Hollomon power-law extrapolation, enabling the post-necking true stress to increase monotonically in accordance with physical plastic flow behavior. Based on the experimental results, the material’s modulus of elasticity was 198 GPa, its yield strength was 1400 MPa, its ultimate tensile strength (UTS) was 1630 MPa, and its fracture stress was 1674 MPa. These values enable the material to be used directly as constitutive input data for crashworthiness evaluations and non-linear finite element analysis (FEA) simulations.