Strain Rate Dependent Mechanical Properties of TWIP Steel

Abstract

The effect of strain rate on the work-hardening behavior of high-manganese twinning-induced plasticity (TWIP) steel has been investigated. The influence of adiabatic heating and deformation rate on the mechanical properties was studied by quasi-static and dynamic tensile tests with synchronous temperature and strain measurements. TWIP steel has excellent strain-hardening behavior under both quasi-static and dynamic loading conditions. Strain rate has negligible effects on yield and tensile strength, but the uniform and total elongation decreases under dynamic tests. TWIP steel has excellent energy absorption (EA) capacity of above 55 kJ/kg at all strain rates compared to dual-phase steels, transformation-induced plasticity steel and ferritic steels. However, the EA of TWIP steel is slightly lower compared to austenitic stainless steels. A rise in temperature due to adiabatic heating has led to the increase of stacking fault energy, thereby resulting in a change of twinning behavior or the promotion of dislocation glide under dynamic loading.

Effect of Discontinuous Yielding on the Strain Hardening Behavior of Fine-Grained Twinning-Induced Plasticity Steel

“…After the valley, the SHR value decreases gradually to the true strain of 0.3, and it fluctuated largely due to the serrations in the further strain range. This valley-type strain hardening behavior at an early stage of the tensile deformation has been reported repeatedly in diverse TWIP steels having an average grain size mostly below 10 µm (Tian et al, 2017;Madivala and Bleck, 2019;Gwon et al, 2020). While the level of the SHR in the valley region varies with the experimental conditions, the gap between the levels of the lower and upper bounds of the valley is about 1,000 MPa or greater in many samples.…”

“…Although the similar increase of the SHR about 1,000 MPa or more at the initial stage of the tensile deformation is frequently observed in fine-grained TWIP steels, discontinuous yielding is not regarded as its principal cause (Madivala and Bleck, 2019;Gwon et al, 2020). Rather, since the analysis of the strain hardening behavior with stages, it is generally interpreted as a result of the onset of deformation twinning, corresponding to "stage B" (Barbier et al, 2009).…”

Estudo do comportamento termomecânico do aço inoxidável AISI 430 por meio da termografia por infravermelho

“…O aumento de temperatura durante a estrição é decorrente da energia de deformação localizada. Além disso, a taxa de deformação varia exponencialmente com a tensão triaxial [18]. Portanto, o aumento da temperatura durante a deformação plástica do material é maior para a maior taxa de deformação.…”

Strain Hardening, Damage and Fracture Behavior of Al-Added High Mn TWIP Steels

“…TWIP steels exhibit extraordinary mechanical properties such as exceptional strength (>1000 MPa), high ductility (>50%) and excellent energy absorption capacity (>55 kJ/kg) making them highly suitable for automotive applications [9][10][11][12][13][14][15]. The sustained and high strain hardening rate (SHR) of TWIP steels can be ascribed to their deformation mechanisms such as dislocation glide, deformation twinning, and ε-martensite transformation.…”

“…The sustained and high strain hardening rate (SHR) of TWIP steels can be ascribed to their deformation mechanisms such as dislocation glide, deformation twinning, and ε-martensite transformation. The materials behavior strongly dependent on their chemical composition, microstructure and deformation conditions [15][16][17][18][19]. The unique characteristic behavior of these steels is the nucleation and propagation of deformation bands during deformation, which results in serrations on the σ-ε curves, known as Portevin-Le Chatelier (PLC) effect [20][21][22].…”