Quantitative Evaluation of Deformation Mechanisms in Austenitic Hadfield Steel under Different Strain Rates

An austenitic Hadfield steel (1.13% C and 12.45% Mn) is tensile tested under different strain rates (10−5, 10−3, and 10−1 s−1) to quantitatively evaluate the contribution of different deformation mechanisms to the flow stress. Dislocation densities are determined through X‐ray diffraction, twin plates characteristics are assessed via transmission electron microscopy, and dynamic strain aging (DSA) is estimated based on carbon concentration revealed by 3D atomic probe tomography. The results indicate a rise in dislocation density, twin volume fraction, and twin plates width with rising strain rates, while DSA exhibits a decrease. Furthermore, no contribution of strain‐induced martensite is observed. At 10−5 s−1, the contribution of forest hardening induced by dislocations, mechanical twining, and DSA recorded ≈300, 400, and 60 MPa, respectively, whereas the respective values at 10−1 s−1 were ≈560, 510, and 6 MPa. Scanning electron microscope analysis of fracture surfaces reveals an increase in dimple features with increasing strain rate, attributed to the concurrent enhancement of strength and ductility.