The study investigated the tensile properties of two low-carbon ferritic low-density steels at strain rates of 1 × 10−4 s−1, 1 × 10−3 s−1, and 1 × 10−2 s−1. These steels underwent cold and warm rolling as well as annealing. Various tensile properties were evaluated, including yie
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The study investigated the tensile properties of two low-carbon ferritic low-density steels at strain rates of 1 × 10−4 s−1, 1 × 10−3 s−1, and 1 × 10−2 s−1. These steels underwent cold and warm rolling as well as annealing. Various tensile properties were evaluated, including yield strength, ultimate tensile strength, strain hardening exponent, energy absorption up to 10 pct engineering strain, and strain rate sensitivity. The results showed that higher strain rates increased yield strength, ultimate tensile strength, and energy absorption in both steels. The strain hardening exponent was determined using the Hollomon and differential Crussard–Jaoul analysis. The electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM) technique were employed to explain the strain hardening response in both steels. Both steels exhibited two distinct stages of deformation, describing their strain hardening behavior. The study observed a decrease in strain rate sensitivity with increasing true strain in both steels. Steel 1 displayed higher strain rate sensitivity than Steel 2, resulting in a delayed necking tendency and higher total elongation. Micrographs of fracture surfaces revealed the presence of quasi-cleavage facets and secondary cracks at strain rates of 1 × 10−3 s−1 and 1 × 10−2 s−1 in both steels. At a lower strain rate of 1 × 10−4 s−1, Steel 1 exhibited a dimple fracture due to its lower strength and higher total elongation, while Steel 2 displayed a quasi-cleavage fracture. The progression of voids in Steel 1 at a strain rate of 1 × 10−4 s−1 was characterized by establishing a relationship between actual thickness strain and the quantity of voids. This analysis provided insights into the steels void formation and growth mechanisms under specific conditions.
