In situ study of austenite formation by dilatometry in a low carbon microalloyed steel

Martín, David San; Rivera-Dı́az-del-Castillo, P.E.J.; García-de-Andrés, C.

doi:10.1016/j.scriptamat.2008.01.019

Cited by 49 publications

(32 citation statements)

References 24 publications

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“…[16][17][18] Good agreement between the measured and calculated volumes of martensite was confirmed when the effect of the alloying element was considered (called the "AE" calculation). Similarly good correspondence has been observed in the previous models [2][3][4][5][6][7][8] used for heat-treatable low-alloy steels when the alloying elements are considered. The other calculation performed (called the "CE" calculation) considered only the carbon effect on the lattice parameters without any other alloying effects, and is shown in Eqs.…”

Section: Notesupporting

confidence: 83%

“…Dilatometric analysis has been widely used for determining quantitative volume fractions of transformed phases, and many investigations have provided analytical models for converting dilatometric data into volume fractions of the constituent phases. [2][3][4][5][6][7][8] However, most of these previous models have been mainly focused on heat-treatable low-alloy steels whose total amount of alloying element is below 5 wt%. The principle used in these models for dilatometric analysis is based on the relative atomic volume change between parent phase and transformed phase.…”

mentioning

confidence: 99%

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Prediction of Martensite Volume Fraction in Fe–Cr–Ni Alloys

Lee

Tyne

2011

ISIJ Int.

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Martensitic stainless steels, such as those in the AISI type 4xx series, have good corrosion resistance, good edge retention, high strength, high hardness, and good wear resistance. 1) Maintaining control over the amount of martensite is important when designing alloy compositions and determining heat treatment conditions, because of the contribution of martensite to the mechanical and electrochemical properties in these stainless steels. Dilatometric analysis has been widely used for determining quantitative volume fractions of transformed phases, and many investigations have provided analytical models for converting dilatometric data into volume fractions of the constituent phases. [2][3][4][5][6][7][8] However, most of these previous models have been mainly focused on heat-treatable low-alloy steels whose total amount of alloying element is below 5 wt%. The principle used in these models for dilatometric analysis is based on the relative atomic volume change between parent phase and transformed phase. This volume change is affected by the changes of the crystal structure, the lattice parameters of the unit cells, and the thermal expansion coefficient during phase transformation. The crystal structure of the phase is determined by the thermo-mechanical conditions, while the lattice parameters can vary due to the type and amount of alloying elements added as a consequence of having different atomic radii. [9][10][11][12] The purpose of the present research is to demonstrate an analytical model for predicting the volume fraction of martensite from a dilation curve by considering the effect of alloying elements in Fe-Cr-Ni stainless steel alloys. The dilation curves of Fe-Cr-Ni alloys with different chemical compositions were selected from literature to verify the analytical model, and the effect of alloying elements is discussed as part of this study.

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Section: Notesupporting

confidence: 83%

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confidence: 99%

Prediction of Martensite Volume Fraction in Fe–Cr–Ni Alloys

Lee

Tyne

2011

ISIJ Int.

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“…Figure 7 shows the dilatometric curves that account for the transformation to austenite during heating of the T91 and T9 steels when the heating rate is settled at 1, 30 and 50 ºC/s and the initial metallurgical state is the as-received one. As expected, the higher the heating rates, the more the temperatures A c1 and A c3 are shifted to higher values [26][27][28][29][30][31] . At the same time, for the 30 and 50 ºC/s cases, there is a clear change of slope in the intercritical portion of the curve at temperatures in the region of 900-925 ºC, suggesting that the transformation to austenite proceeds with two distinct regimes.…”

Section: 2supporting

confidence: 78%

Heterogeneous austenite grain growth in martensitic 9cr steel: Coupled influence of initial metallurgical state and heating rate

Zavaleta-Gutierrez

Luppo

Danón

et al. 2013

Materials Science and Technology

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The coupled influence of the initial metallurgical state and the heating rate to austenite on the occurrence of heterogeneous grain growth during austenitization of an ASTM A213 -T91 steel has been studied. To that aim, two-step thermal cycles were designed. In the first step, different starting metallurgical conditions were obtained by treating the as-received material at 780 C for increasing times up to 6 hours. In the second step, "in situ" austenitization was performed by heating to austenite at rates of 1, 30 and 50 ºC/s and then holding at 1050 ºC for 30'.Two types of austenite grain structures were obtained after austenitization, namely, homogeneous and heterogeneous. The homogeneous structure was characterized by a smooth size distribution of approximately equiaxed, normally grown grains. The heterogeneous structure, instead, exhibited the exaggerated growth of a few austenite grains embedded in a small to medium-sized "matrix".For the 1 ºC/s heating rate and all of the initial metallurgical states, only homogeneous grain growth was observed, whereas for the 50 ºC/s heating rate only heterogeneous grain growth was observed regardless the starting metallurgical condition. Instead, the occurrence of homogeneous or heterogeneous grain growth after heating at 30 ºC/s was observed to be a function of the time of previous tempering. Some explanations of the phenomenon are advanced taking into account the precipitation state of second phases.

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“…Dilatometry is a powerful technique to study the phase transformation kinetics of steels [1][2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Method to Evaluate the Kinetics of Bainite Transformation in Low-Temperature Nanobainitic Steel Using Thermal Dilatation Curve Analysis

Mao

et al. 2017

Metals

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Abstract:The aim of this work was to develop a method to evaluate the kinetics of bainite transformation by theoretical deduction and thermal dilatation curve analysis. A Gleeble-3500 thermomechanical simulator and dilatometer (DIL805A) were employed to study the isothermal transformation in deformed (360 • C, 600 • C, and 860 • C) and undeformed conditions. The thermal dilatation information during isothermal transformation was recorded, and the dilatation curves were well smoothed. By taking a derivative of the dilation curve with respect to the transformation time, the peak time of transformation rate (PTTR) was obtained, which can serve as the essence of isothermal transformation time. The relative change of length (∆L/L) due to phase transformation was theoretically deduced, and the effect of temperature was taken into consideration. Combing experimental data, the volume fraction of bainite in isothermal transformation was calculated. Making a graph of volume fraction versus PTTR was a good method to evaluate the kinetics of bainitic transformation clearly and concisely which facilitated optimization of the preparation technique for low-temperature nanobainitic steel.

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In situ study of austenite formation by dilatometry in a low carbon microalloyed steel

Cited by 49 publications

References 24 publications

Prediction of Martensite Volume Fraction in Fe–Cr–Ni Alloys

Prediction of Martensite Volume Fraction in Fe–Cr–Ni Alloys

Heterogeneous austenite grain growth in martensitic 9cr steel: Coupled influence of initial metallurgical state and heating rate

Method to Evaluate the Kinetics of Bainite Transformation in Low-Temperature Nanobainitic Steel Using Thermal Dilatation Curve Analysis

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