Analysis of the tensile behavior of a TWIP steel based on the texture and microstructure evolutions

Abstract

a b s t r a c tThe texture and microstructure evolutions of a fine-grained TWIP steel subjected to tensile tests at room temperature were investigated in relation to the mechanical behavior. This steel combines both high ductility and strength owing to the TWIP effect. Also the steel exhibits a high strain hardening rate that evolves according to five stages, which are related to the microstructure and texture evolutions and characteristics. The formation of nano-twins in the initial stage of deformation leads to an increase in strain hardening rate. The development of the pronounced <1 1 1> fiber in the tensile direction sustains mechanical twinning and maintains the strain hardening rate on a high level. The resulting microstructure exhibits several types of twin configurations and sub-boundaries with high misorientations due to intense activities of dislocation glide. The twin volume fraction was estimated to be 9% at the final stage of tensile deformation. The new orientations generated by mechanical twinning do not change considerably the final texture.

Transmission Electron Microscopy Observation of Twin Variant Selection in Austenitic Twinning-Induced Plasticity Steel

“…Although the mean grain size of the specimens used in the present experiment was 3.814 μm, such effects could potentially occur because the sizes of individual grains were very different. Additionally, unexpected errors may exist because of interactions with surrounding grains (Barbier et al, 2009;Han et al, 2004;Karaman et al, 2000;Pérez-Prado & Doncel, 2006;Vercammen et al, 2004).…”

Investigation of Deformation Mechanisms in Deep-Drawn and Tensile-Strained Austenitic Mn-Based Twinning Induced Plasticity (TWIP) Steel

“…[1][2][3][4][5][6][7] With increasing e ac eq , deformation is facilitated initially by dislocation multiplication, followed by twinning or martensitic transformations, providing barriers for further dislocation slip. [1][2][3][4][5][6][7] Austenite with a relatively low stability can transform by means of c fi e fi a 0 martensitic transformations, resulting in a high work-hardening rate. Stability against c fi e-martensite transformation often implies stability against c fi (e fi) a 0 -martensite transformation.…”

“…Equation [4] can be defined in an analogous manner for the W parameter. In the previous work, [17] the larger defect type D 1 was attributed to perfect dislocations, whereas the smaller defect type D 2 was attributed to partial dislocations.…”

“…One of the latest developments is austenitic Mn-based twinning induced plasticity (TWIP) steels, which combine high strength with high ductility. These superior mechanical properties are a result of deformation mechanisms involving twinning or plasticity-induced transformation [1][2][3][4][5][6] related to the austenite (c) stability. The deformation mechanisms in these Mn-based TWIP steels have been most intensively investigated for tensile straining, [3][4][5][6] leaving the role of large strain on the twinning or transformation-induced plastic deformation mechanism less exposed.…”

“…These superior mechanical properties are a result of deformation mechanisms involving twinning or plasticity-induced transformation [1][2][3][4][5][6] related to the austenite (c) stability. The deformation mechanisms in these Mn-based TWIP steels have been most intensively investigated for tensile straining, [3][4][5][6] leaving the role of large strain on the twinning or transformation-induced plastic deformation mechanism less exposed. [7] In the present work, the effect of both deep drawing and tensile straining on the defect and microstructure evolution in Mn-based TWIP steels was experimentally investigated using magnetic measurements, X-ray diffraction (XRD), and positron annihilation.…”