## 1 Introduction
Limits for the activation of the individual mechanisms can rather be regarded as threshold values of transition regions, in which several deformation mechanisms can also be activated in parallel [19; 22]. Despite significantly differing information, a range of mean SFEs between 20 and 50 mJ/m\({}^{2}\) can be deduced from the literature, in which the TWIP effect is the preferred deformation mechanism [1; 23; 24]. While deformation-induced twinning is replaced by the TRIP effect in the range of low SFEs below 20 mJ/m\({}^{2}\), dislocation slip represents the dominant deformation mechanism in the range of high SFEs \(>\) 50 mJ/m\({}^{2}\)[25]. In this area of high SFEs, another subgroup of HMnS, the aforementioned density-reduced light-weight steels, have gained significant attention in recent investigations [26]. Following the TWIP and TRIP effect, new deformation mechanisms, namely the shear-band-induced plasticity (SIP) [27], the microband-induced plasticity (MBIP) [28], the slip-band refinement-induced plasticity (SRIP) [29] or the dynamic slip band refinement (DSBR) [30], have been reported. A detailed summary of these deformation mechanisms is presented in [31]. In HMnS, the SFE itself is strongly influenced by the alloying concept as well as the deformation temperature, highlighting the influence of these two parameters on the active deformation mechanisms [5; 13; 14; 18; 32]. According to the literature, the alloying elements can primarily be divided into elements increasing the SFE (C, Al, Ni and Cu) and elements that cause a decrease in the SFE (Cr and Si). The main alloying element Mn has a parabolic influence on the SFE in binary Fe-Mn alloys as well as in the Fe-Mn-C alloy system, i.e., the SFE decreases with increasing Mn content up to about 13 wt.% and then increases again with further addition of Mn [32; 33; 34; 35]. In addition, the influence of Ni on the SFE shows different tendencies depending on the chemical composition of the base material as well as the range of the Ni concentration [32]. Furthermore, the deformation temperature also has a significant effect on the resulting SFE as it increases with higher temperatures [5]. Using the thermodynamic approach of [PERSON] and [PERSON] [36], [PERSON] et al. [37] for example were able to determine the Gibbs free energy and, hence, the SFE as a function of temperature for an Fe-Mn-Si-Al alloy, demonstrating a proportional increase in the SFE with increasing temperature. The influence of temperature on the SFE was additionally discussed by [PERSON] et al. [38] for the austenitic X40 MnCrAl19-2 TWIP steel, the alloy being in focus of the present study. Investigating the effect of pre-deformation temperature on the fatigue behavior, the authors showed that pre-deformation at room temperature (RT) resulted in deformation-induced twinning, whereas for a pre-deformation temperature of \(-196\)\({}^{\circ}\)C, the TWIP-effect was accompanied by the formation of \(\varepsilon\)- as well as \(\alpha^{\prime}\)-martensite. An elevated pre-straining temperature of 400 \({}^{\circ}\)C led to the suppression of both effects. Due to their outstanding mechanical properties as well as the possibility to overcome the strength-ductility trade-off, HMnS exhibit a great potential for the development of components for the mobility sector, e.g., crash-relevant body structures. As many of the intended applications of these steels will be subjected to cyclic loadings during their service life, the fatigue behavior is of utmost importance. As a result, the crack growth behavior as well as the fatigue properties in different regimes, including low-cycle and high-cycle fatigue (LCF/HCF) regimes, have been investigated in several studies focusing on the influences of twinning and martensitic phase transformation, i.e., TWIP- and TRIP-effect, as well as the influence of grain size, strain rate, deformation temperature and pre-deformation on the fatigue behavior. A detailed literature survey on these studies is presented in [39].