Modelling the effect of carbon on deformation behaviour of twinning induced plasticity steels

Abstract

In this article, a physical model describing the deformation behaviour of Twinning Induced Plasticity (TWIP) steels has been extended to include the effect of carbon content. The experimental validation and the analysis show that carbon mainly controls the maximum number of dislocations piled up at the twin boundary, resulting in the increase of back-stresses (i.e. kinematic hardening) and therefore the work hardening rate. This explanation seems to be in agreement with recent TEM observations.

A thermo-mechanical correlation with driving forces for hcp martensite and twin formations in the Fe–Mn–C system exhibiting multicomposition sets

“…If a sufficiently positive driving force is needed to form deformation-induced hcp martensite or twin, Mn and C contents can be adjusted accordingly at production. This result may explain previous reports [6, 17, 43] where deformation twins were either present or absent in alloys having similar SFE values. Bouaziz et al [6] compared Fe–30Mn and Fe–22Mn–0.6C alloys with similar SFE values where, after deformation, extensive mechanical twinning was observed in the Fe–22Mn–0.6C alloy, whereas no twins were found in the Fe–30Mn alloy (figure 6).…”

Performance and Characterization of TWIP Steels for Automotive Applications

“…Guided by their physical model [72,75], Bouaziz et al [76] used the tensile response of several compositions of Fe-Mn-C to develop a semi-phenomenological constitutive model that depends on the weight percent of C and Mn, which is useful for alloy design. Both the initial yield strength and the coefficient of the stress associated with twinning depend on C and Mn via empirical relations.…”

“…The dislocations piled up at twin boundaries increase the back-stress [75]. Therefore, kinematic hardening is associated with twinning and is expressed as a power law,…”

Suppression of dislocations at high strain rate deformation in a twinning-induced plasticity steel

“…One interesting phenomenon found in TWIP steels is the decrease of work-hardening rate at higher strain rate [7][8][9][10][11][12]. As the work-hardening rate in TWIP steels depends largely on the evolution of dislocations and deformation twins [13][14][15], such phenomenon suggests that a higher strain rate may lead to the suppression of dislocations and deformation twins in TWIP steels. Experimental support for the suppression of deformation twins has been provided in [11,12].…”