scholarly journals Influence of Vanadium Microalloying on Deformation-Induced Pearlite Transformation of Eutectoid Steel

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 268 ◽  
Author(s):  
Zhen Cai ◽  
Xinping Mao ◽  
Siqian Bao ◽  
Gang Zhao ◽  
Yaowen Xu
Keyword(s):  
Microalloyed Steel ◽  
Small Strain ◽  
Vanadium Content ◽  
Transformation Kinetics ◽  
Eutectoid Steel ◽  
Vanadium Nitrides ◽  
Austenite Grain ◽  
Thermomechanical Simulation ◽  
Vanadium Carbides ◽  
Kinetics Of

In order to investigate the influence of vanadium microalloying on deformation-induced pearlite transformation (DIPT) of eutectoid steel, thermomechanical simulation tests were carried out in this study. The following four compositions of vanadium microalloying were applied in the tests: vanadium free in Steel A, vanadium content of 0.1 mass% in Steel B, vanadium content of 0.27 mass% in Steel C, and vanadium content of 0.1 mass% with the addition of 0.02 mass% N in Steel D. The dissolution of vanadium and precipitation of vanadium carbides, nitrides, or carbonitridesand the effect of vanadium microalloying on the fraction and morphology of deformation-induced pearlite for different magnitudes of strain were examined, and the mechanism of the effect was elucidated. The results revealed that DIPT could be significantly improved by vanadium microalloying with the addition of N but decreased and postponed without the addition of N because vanadium nitrides or carbonitrides were precipitated in austenite under a small strain and facilitated the nucleation of pearlite both along the boundary of austenite grain (AG pearlite) and intragranular (IG pearlite). Moreover, transformation kinetics of DIPT was fitted and compared. The results further revealed that the rate of DIPT in vanadium-microalloyed steel with the addition of N was twice as fast as that in the vanadium-free steel. In order to ensure the complete spheroidization of lamellar cementites in vanadium-microalloyed steel, a comparison of the morphology of cementites revealed that a greater magnitude of strain was required.

Alloying Effects on Reverse Transformation to Austenite from Pearlite or Tempered Martensite Structures

2010 ◽  
Vol 638-642 ◽  
pp. 3400-3405 ◽  
Author(s):  
Goro Miyamoto ◽  
Zhao Dong Li ◽  
Hirokazu Usuki ◽  
Tadashi Furuhara
Keyword(s):  
Decomposition Reaction ◽  
Reverse Transformation ◽  
Transformation Kinetics ◽  
Tempered Martensite ◽  
Austenite Grain Size ◽  
Austenite Grain ◽  
Cr Addition ◽  
Alloying Effects ◽  
Kinetics Of ◽  
Martensite Structure

Reverse transformation has been frequently used to refine austenite grain size for refining ferrite, pearlite and martensite structures. However, kinetics and microstructure change during reverse transformation to austenite has not been examined systematically compared with the austenite decomposition reaction. Therefore, alloying effects of 1mass% Mn, Si and Cr on reverse transformation kinetics from pearlite and tempered martensite structures in Fe-0.6mass%C alloys were investigated in this study. Vickers hardness of all the specimens increases with increasing holding time at 1073K because reversely-formed austenite transforms to martensite by quenching. In the reverse transformation from pearlite structure, the kinetics of reverse transformation is hardly changed by the Mn addition while Si and Cr additions delay it. Kinetics of reverse transformation from tempered martensite structure becomes slower than from the pearlite structure in all the alloys. In particular, retarding effect by the Cr addition is most significant among those elements.

The Influence of Increased Cr Content and Austenite Grain Size on the Kinetics of Phase Transformations when Cooling Hypo-Eutectoid Steel

2006 ◽  
Vol 258-260 ◽  
pp. 421-426
Author(s):  
Ignacy Wierszyłłowski
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Carbon Steel ◽  
Phase Transformations ◽  
Austenite Phase ◽  
Eutectoid Steel ◽  
Austenite Grain Size ◽  
Cr Content ◽  
Austenite Grain ◽  
Kinetics Of

The paper presents the influence of the grain size and a little higher Cr content on the kinetics of austenite phase transformations during continuous cooling of hypo-eutectoid steel. The kinetics of austenite phase transformations during continuous cooling were determined by means of analysis of the dilatometric curves and structure investigations. The influence of the austenite grain size and the higher Cr content was analysed in two hypoeutectoid steels containing about 0.4% C. One of them had, Cr content higher, by about 1%. In both steels, the austenite grain size was changing insignificantly up to the austenitising temperature of about 950fl. Above that temperature, the austenite grain size in carbon steel grew much quicker than that in the steel with Cr addition. The austenite grain in the Cr enriched steel was smaller than that in carbon steel and, in spite of that, the duration of cooled austenite transformations were several times longer. This means that the phase transformations are much more strongly influenced by the addition of chromium slowing down carbon diffusion in austenite, than by the austenite grain size. For each phase transformation in the examined steels, the activation energy of the transformation has been determined. The activation energy of all the phase transformations varied slightly with the increase of austenitising temperature. On the basis of the obtained results, curves of true isothermal transformations have been developed for the beginning of the phase transformations in both steels, related to infinitely quick cooling down to the transformation temperature.

Study on Deformation-Induced Pearlite Transformation in Vanadium Microalloyed Eutectoid Steel

2019 ◽  
Vol 1156 ◽  
pp. 17-24
Author(s):  
Cai Zhen ◽  
Xin Ping Mao ◽  
Si Qian Bao ◽  
Zhao Gang
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Microalloyed Steel ◽  
Hot Compression ◽  
Lower Strain Rate ◽  
Compression Tests ◽  
Eutectoid Steel ◽  
Lower Strain ◽  
Vanadium Carbides

In this paper, the hot compression tests were performed to study on deformation-induced pearlite transformation in vanadium microalloyed eutectoid steel. The results showed that volume fraction of deformation -induced pearlite were higher and the pearlite were spheroidized better under lower strain rate and higher strain in vanadium microalloyed steel. Ferrite grains and granular cementites were further refined through vanadium microalloying combined with deformation-induced pearlite transformation .Vanadium dissolved in γmatrix could retard deformation-induced pearlite transformation under low strain, vanadium carbides precipitated due to strain-induced precipitation eliminate the retardation when the strain was increased to a certain extent. Under heavy deformation, ferrite grains and granular cementites in vanadium microalloyed steel were finer compared with vanadium free steel.

scholarly journals Continuous Cooling Transformation Behaviour and Bainite Transformation Kinetics of 23CrNi3Mo Carburised Steel

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 48
Author(s):  
Wenjun Song ◽  
Min Lei ◽  
Mingpan Wan ◽  
Chaowen Huang
Keyword(s):  
Phase Transformation ◽  
Volume Fraction ◽  
Austenite Formation ◽  
Steel Matrix ◽  
Transformation Kinetics ◽  
Bainite Transformation ◽  
Continuous Cooling ◽  
The Matrix ◽  
Dimensional Growth ◽  
Kinetics Of

In this study, the phase transformation behaviour of the carburised layer and the matrix of 23CrNi3Mo steel was comparatively investigated by constructing continuous cooling transformation (CCT) diagram, determining the volume fraction of retained austenite (RA) and plotting dilatometric curves. The results indicated that Austenite formation start temperature (Ac1) and Austenite formation finish temperature (Ac3) of the carburised layer decreased compared to the matrix, and the critical cooling rate (0.05 °C/s) of martensite transformation is significantly lower than that (0.8 °C/s) of the matrix. The main products of phase transformation in both the carburised layer and the matrix were martensite and bainite microstructures. Moreover, an increase in carbon content resulted in the formation of lamellar martensite in the carburised layer, whereas the martensite in the matrix was still lath. Furthermore, the volume fraction of RA in the carburised layer was higher than that in the matrix. Moreover, the bainite transformation kinetics of the 23CrNi3Mo steel matrix during the continuous cooling process indicated that the mian mechanism of bainite transformation of the 23CrNi3Mo steel matrix is two-dimensional growth and one-dimensional growth.

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