# Effect of Strain on Transformation Diagrams of 100Cr6 Steel

^{1}

^{2}

^{*}

## Abstract

**:**

## 1. Introduction

_{r3}is the transformation temperature of austenite to ferrite and A

_{r1}is the transformation temperature of austenite to pearlite by the cooling of hypoeutectoid steels). In addition, from Figure 2, it is evident that with increasing deformation (up to about 0.4), the area of ferritic transformation is narrowed—thus, the pearlitic transformation is accelerated [26]. This thesis confirms that even our previous research detected that the effect of previous deformation leads to an increased fraction of pearlite and ferrite [11,20].

## 2. Materials and Methods

_{c1}and A

_{cm}, which represent the temperatures of the transition during heating. In this case, the specimen was heated at 5 °C/s to 500 °C, and the heating rate was then slowed down to 10 °C/min (0.167 °C/s) to locate the transformation area. Evaluation of the measured data was carried out using the semi-automatic CCT software (Dynamic Systems Inc., Poestenkill, NY, USA), which uses the tangential method in combination with the derivation of the dilatation curve to determine the transformation temperatures. The result of this test is shown in Figure 5.

_{c1}and A

_{cm}temperatures), other specimens were uniformly preheated at 850 °C with a subsequent 10 min dwell at this temperature in order to construct (D)CCT diagrams. After that (in the case of the CCT diagram), the specimens were continuously cooled to room temperature by the constant cooling rates in the range of 0.2–150 °C/s. To achieve cooling rates above 25 °C/s, the specimens (with cooling rates of 60 and 150 °C/s = only for construction of CCT diagram) had to have a special hollow-head structure for high-speed cooling by air nozzles. Unfortunately, the disadvantage of these specially designed specimens is the inability to perform a deformation [45,46]. The temperature of heating at 850 °C is normal for the construction of CCT diagrams of 100Cr6 steel [42,43,44,47,48].

## 3. Results and Discussion

#### 3.1. CCT Diagram

#### 3.2. DCCT Diagram—Deformation e = 0.35

#### 3.3. DCCT Diagram—Deformation e = 1

#### 3.4. Comparison of the (D)CCT Diagrams

#### 3.5. Comparison of the Hardness HV30

## 4. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

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**Figure 1.**Influence of alloying, thermomechanical factors, and structure state on transformation kinetic [8].

**Figure 2.**Effect of deformation on the ferritic transformation of HSLA (High-Strength Low-Alloy) steel [26]. The temperatures of Ar1 and Ar3 represent the temperatures of the transition during cooling.

**Figure 3.**Effect of strain rate on the ferritic transformation of HSLA steel [26]. The temperatures of Ar1 and Ar3 represent the temperatures of the transition during cooling.

**Figure 4.**Influence of the previous deformation on martensite (Ms) temperature in selected low-alloyed steels [23].

**Figure 7.**The analysis of the influence of temperature on the austenitic grain size of the 100Cr6 steel. (

**a**) scheme of austenitic grain size (AGS) experiment; (

**b**) Microstructure of austenite, AGS = 9.8 µm.

**Figure 8.**Selected examples of dilatation curves, including determination of transformation points by use of the tangential method.

**Figure 10.**SEM microstructures of selected samples, without deformation. M, martensite; C, carbides; P, pearlite; T(P), troostite; RA, retained austenite.

**Figure 11.**CCT diagram of 100Cr6 steel—according to [51].

**Figure 12.**CCT diagram of 100Cr6 steel—according to [42].

**Figure 13.**Deformation continuously cooling transformation (DCCT) diagram of the 100Cr6 steel—after the deformation of e = 0.35.

**Figure 15.**The microstructures (SEM and light-microscopy) of selected samples and after the deformation of e = 0.35. M, martensite; C, carbides; T(P), troostite.

**Figure 17.**The microstructures (light-microscopy and SEM) of selected samples and after the deformation of e = 1. M, martensite; C, carbides; T(P), troostite.

**Figure 19.**Comparison of measured HV30 hardness in dependence on cooling rate and deformation value.

C | Mn | Si | P | S | Cr |
---|---|---|---|---|---|

0.994 | 0.38 | 0.324 | 0.011 | 0.001 | 1.45 |

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**MDPI and ACS Style**

Kawulok, R.; Schindler, I.; Sojka, J.; Kawulok, P.; Opěla, P.; Pindor, L.; Grycz, E.; Rusz, S.; Ševčák, V.
Effect of Strain on Transformation Diagrams of 100Cr6 Steel. *Crystals* **2020**, *10*, 326.
https://doi.org/10.3390/cryst10040326

**AMA Style**

Kawulok R, Schindler I, Sojka J, Kawulok P, Opěla P, Pindor L, Grycz E, Rusz S, Ševčák V.
Effect of Strain on Transformation Diagrams of 100Cr6 Steel. *Crystals*. 2020; 10(4):326.
https://doi.org/10.3390/cryst10040326

**Chicago/Turabian Style**

Kawulok, Rostislav, Ivo Schindler, Jaroslav Sojka, Petr Kawulok, Petr Opěla, Lukáš Pindor, Eduard Grycz, Stanislav Rusz, and Vojtěch Ševčák.
2020. "Effect of Strain on Transformation Diagrams of 100Cr6 Steel" *Crystals* 10, no. 4: 326.
https://doi.org/10.3390/cryst10040326