Figure 1: Strengthening of FeMnC TWIP steel by pre-torsion treatment.
From: Evading the strength–ductility trade-off dilemma in steel through gradient hierarchical nanotwins
(a) Torsion experiments on samples at four different torsional angles. The resultant shear strain γ is a function of position r along the radial direction, γ=θrL−1, where θ is the overall twist in a selected region with uniform diameter and length L=70 mm. For a nominal pre-torsion of 180°, the maximum shear strain in the sample with R=5 mm is ~0.2, where R is the radius of the sample. (b) Variation of hardness in the radial direction. Values represent average from n=10 tests (error bars: s.d.). Data are for as-received samples, samples subject to 180° torsion, and those subject to 180° pre-torsion and subsequent tension. (c) Stress–strain curves for the pre-torsioned samples. (d) Hardening modulus as a function of strain upon stretching of pre-torsioned samples.
