Microstructure and tensile behaviour of 15–24 wt-Mn TWIP steels

Abstract

The present study examines the microstructure and tensile behaviour of twinning induced plasticity steel with different Mn contents. The results show that reducing the Mn content from 24 to 15 wt-% is beneficial for the improvement of the tensile strength and fracture strain of the steels. The effect of Mn content on the microstructure and workhardening behaviour as well as the effect of strain rate on the microstructure and tensile behaviour is discussed.

Critical assessment 19: Stacking fault energies of austenitic steels

“…94 Pierce et al 56 obtained the σ values by subtracting the DG g 1 and E str values from the SFE values measured using the TEM. The σ values range from 8.6 to 11.8 mJ m −2 for Fe- (22,25,28)Mn-3Al-3Si and Fe-18Mn-0.6C-(0,1.5)Al-(0,1.5)Si (wt-%) steels; the σ value decreases from 32.5 to 15.7 mJ m −2 with increasing Mn concentration in Fe- (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)Mn (wt-%) binary steels.…”

“…Vitos et al 86 also collected the SFE values of Fe- (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) Cr- (13)(14)(15)(16))Ni (at.-%) steels measured using the TEM and the XRD from the literature, and compared them with the values calculated using ab initio simulation. They found that the addition of Cr to austenitic stainless steels lowers their SFE values.…”

“…The temperature as well as alloying elements is also an important factor for the SFE. Rémy et al 122 gave an overview of a temperature dependence of SFE, which was measured using the TEM, in Fe- (17)(18)(19)(20)Cr- (13)(14)(15)Ni and Fe-20Mn-4Cr-0.5C (wt-%) steels. They reported that the SFE value of Fe-Cr-Ni steels increased by approximately 0.1 mJ m −2 per K when the temperature rose from 300 to 400 K and that those of Fe-Mn-Cr-C steels were arisen by 0.06 mJ m −2 per K with increasing temperature from 300 to 390 K; these results stemmed from the improvement of γ stability with an increase in temperature.…”

“…[1][2][3][4][5][6][7][8][9][10][11] The strengthening mechanism of the fcc steels is strongly dependent upon the stacking fault energy (SFE) of γ austenite. 1,4,8,[10][11][12][13][14][15][16][17][18][19][20][21] It is known that whereas the mechanical stimulation of ε martensite is a dominant strengthening mechanism when the SFE value is less than approximately 20 mJ m −2 , TWIP begins to dominate as the SFE value ranges from 20 to 40 mJ m −2 . 1,2,8,9 For TWIP steels, the SFE influences a 'critical stress' for mechanical twinning, 13,[22][23][24][25][26] the twin fraction [27][28][29] and the twin thickness.…”

Strain rate-dependent hardening with dislocation-twin interaction of Fe–Mn–Al–C steel using crystal plasticity

“…The studies above have provided bases for the theoretical modelling of twinning-induced macroscopic deformation behaviour of TWIP steel. The mechanical properties in the deformation process of TWIP steel are highly dependent on strain rate, which has been widely investigated [9][10][11]. However, the influence of strain rate on hardening behaviour associated with twinning mechanism needs to be paid more attentions.…”