## 3 Results and Discussion
### Influence of Cr Content on the CCT and DCCT Diagrams and Hardness  
As commonly observed [13; 14; 15; 16; 17], the hardenability of the present steels increases with increasing Cr content. This shows as a lowering of transformation temperatures in both CCT and DCCT diagrams as the Cr content increases, see Figure 8, which promotes the formation of the low-temperature transformation product BF and reduces the formation of the transformation products that form at relatively high temperatures, i.e., PF and GB.  
As can be seen from Figure 9, the effect of the preceding hot deformation on the transformation products is decreased with increasing Cr content. In the case of Steel I, with the lowest Cr content (1 wt.%), prior hot deformation had a great effect on the transformation curves which shifted to significantly higher temperatures as a result of ferrite formation. This caused a significant drop in hardness as can be seen from Figure 10. This behavior results from the dislocation substructure formed in the austenite after deformation in the non-recrystallization region, which provides nucleation sites and diffusional paths for the diffusional transformation products [18; 19]. In the case of Steel II (2.5 wt.% Cr), the preceding hot deformation shifted the transformation curves of ferrite to higher CRs, while  
Figure 7: Scanning electron microscopy (SEM) micrographs of Steel I (**a,d**), II (**b,e**), and III (**c,f**) with austenite deformation after cooling at 80 and 2 \({}^{\circ}\)C/s, respectively. Abbreviations: BF = bainitic ferrite, GB = granular bainitic, PF = polygonal ferrite, and P = pearlite.  
shifted to lower temperatures. These changes led to an increase in the formation of PF and GB, while the formation of BF was reduced even at high CRs. However, in the case of Steel III with the highest Cr content (4.0 wt.%), the effect of the preceding hot deformation on the transformation temperatures and products became very small. The transformation curves were shifted to slightly lower temperatures, but this effect decreased with increasing cooling rate. Austenite deformation increased the fraction of GB somewhat at the lower CRs. The insensitivity to deformation also reflected in the final hardness as a function of cooling rate as shown in Figure 10.  
Figure 8: Influence of Cr content on the transformation temperatures for CCT diagrams (**a**) and DCCT diagrams (**b**). Abbreviations: \(\mathrm{F_{s}}\) = ferrite start temperature, \(\mathrm{F_{f}}\) = ferrite finish temperature, \(\mathrm{B_{s}}\) = bainite start temperature, and \(\mathrm{B_{f}}\) = bainite finish temperature.  
Figure 10: Influence of CR, Cr content, and prior hot deformation on hardness.  
Figure 9: Influence of austenite deformation on CCT curves for a Cr content of 1 wt.% (**a**), 2.5 wt.% (**b**), and 4 wt.% (**c**). CCT curves bold and DCCT curves dotted. Abbreviations: \(\mathrm{F_{s}}\) = ferrite start temperature, \(\mathrm{F_{f}}\) = ferrite finish temperature, \(\mathrm{B_{s}}\) = bainite start temperature, and \(\mathrm{B_{f}}\) = bainite finish temperature.  
At all CRs, the hardness values increased with increasing the Cr content (Figure 10). This is due to the higher solid solution strengthening combined with the lower transformation temperatures which refine the microstructure significantly (see Figure 6a-c). Overall, it can be concluded that austenite deformation with a high Cr content lowers the transformation temperatures, while transformation temperatures are increased in the case of low Cr contents.