Effect of Strain on Transformation Diagrams of 100Cr6 Steel

Abstract

Based on dilatometric tests, the effect of various values of previous deformation on the kinetics of austenite transformations during the cooling of 100Cr6 steel has been studied. Dilatometric tests have been performed with the use of the optical dilatometric module of the plastometer Gleeble 3800. The obtained results were compared to metallographic analyses and hardness measurements HV30. Uniaxial compression deformations were chosen as follows: 0, 0.35, and 1; note that these are true (logarithmic) deformations. The highly important finding was the absence of bainite. In addition, it has been verified that with the increasing amount of deformation, there is a further shift in the pearlitic region to higher cooling rates. The previous deformation also affected the temperature martensite start, which decreased due to deformation. The deformation value of 1 also shifted the critical cooling rate required for martensite formation from the 12 °C/s to 25 °C/s.

Effects of Austenitization Temperature and Pre-Deformation on CCT Diagrams of 23MnNiCrMo5-3 Steel

“…Such behavior is surprising and inconsistent with the results of many other studies on the effect of plastic deformation on the continuous cooling transformation diagrams [ 1 , 2 , 3 , 5 , 6 , 10 , 14 , 22 , 38 , 39 , 40 , 41 , 58 ]. However, less unambiguous data can be found comparing the CCT and DCCT diagrams for some steels.…”

“…The kinetics of austenite decomposition is not only fundamentally influenced by the chemical composition of the steel but also by the parameters of the structure entering the given phase transformation. The prior microstructure depends on the austenitization conditions, the parameters of the pre-deformation, and the cooling time [ 1 , 2 , 3 , 4 , 5 , 6 ]. The continuous cooling transformation (CCT) diagrams show the temperatures of the phase transformations, and the individual decomposition products of austenite depend on the cooling at different rates.…”

Continuous cooling transformation diagrams of HSLA steel for seamless tubes production

“…The final cooling rate makes it possible to control the austenite softening processes, and phase transformations during decomposition of austenite and grain growth. The published results [4][5][6][7][8][9][10][11][12], and our experiences gained in the laboratory conditions using the hot deformation simulator Gleeble 3800 [13][14], as well as the semi-continuous hot rolling mill [15][16] prove the crucial role of the cooling parameters after hot forming. This can be deduced from the continuous cooling transformation diagrams, especially when considering the previous deformation history.…”

“…This can be deduced from the continuous cooling transformation diagrams, especially when considering the previous deformation history. Recently, thanks to two dilatometer systems available on the Gleeble simulator, the researchers of the VŠB-TUO have created continuous cooling transformation diagrams for a number of chemically very different steel grades in the traditional version (CCT), as well as after the previous deformation of austenite (DCCT) -see [17,18], for example. The effect of austenite deformation is very complex and manifests itself differently, e.g., by refining the prior austenite grains due to static recrystallization or by the modification of the austenite decomposition kinetics as a result of deformation strengthening.…”

“…The nucleation rate is high; however, the mobility of phase interfaces is severely decelerated by a high density of dislocations in austenite and that is why the final fraction of ferrite decreases. In the case of very large plastic deformation, the high nucleation rate compensates the slow growth of nuclei and the resulting ferrite fraction is approximately the same as in the case of austenite not affected by plastic deformation; however, the ferrite grains are much finer [17,[23][24][25][26][27][28].…”