The role of welding parameters on the control of the microstructure and mechanical properties of rails welded using FBW

Bauri, Luiz Felipe; Alves, Luiz Henrique Dias; Pereira, Henrique Boschetti; Tschiptschin, André Paulo; Goldenstein, Hélio

doi:10.1016/j.jmrt.2020.05.030

Cited by 24 publications

(37 citation statements)

References 11 publications

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“…Nowadays, with the continuous increase of train operation speed and transported axle load, the use of better rail steels and the improvement of welding techniques have been sought with the aim to increase the rail life and to decrease the cost of track maintenance. This actual need has been the driving force for recent developments and for the increasingly number of published studies addressing the improvement and innovation in rail steel manufacturing and welding [1][2][3][4][5][6][7] .…”

Section: Introductionmentioning

confidence: 99%

“…Pearlitic steels are widely used in the railway industry worldwide due to their good wear resistance and satisfactory toughness, in association with its relatively manufacturing low cost. The mechanical properties of pearlitic steels are controlled by the microstructures arising from their thermomechanical processing, especially by characteristics such as previous austenitic grain size, pearlite interlamellar spacing and pearlite colony size [1][2][3][4][5][6][7][8][9][10][11] . According to the AREMA 12 , these rail steels presenting pearlitic microstructures can be classified into two classes: standard and premium.…”

Section: Introductionmentioning

confidence: 99%

“…According to some recent published studies, it is possible to improve the pearlitic rail performance improving its microstructural characteristics. For this purpose, authors have been pointing out the importance to well characterize and to understand the rail steel phase transformations aiming to better design the thermal cycles to which they are submitted during their manufacturing or welding processes [1][2][3][4][5] .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Characterization and Prediction of Continuous Cooling Transformations in Rail Steels

Rodrigues

Faria

2021

Mat. Res.

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This paper presents the characterization of austenite to pearlite transformation in rail steels (premium and standard) using dilatometry. The critical transformation temperatures were measured as a cooling rate function and the obtained microstructures were qualitatively and quantitatively characterized. Aiming to study the transformation kinetics, three equations proposed by technical literature were evaluated in order to predict the transformation evolution. Experimental and calculated CCT diagrams were compared. It was concluded once the kinetics of phase transformation in rail steels is well characterized, it can be used as reference to enable suitable heat treatment to obtain pearlitic microstructures for the standard steel as refined as those of premium. The minor prior austenite grain size of the standard steel favoured the pearlite nucleation, however its highest Mn, Nb and Si contents delayed the growth stage. All equations evaluated in order to predict the kinetics of austenite to pearlite transformation under continuous cooling were satisfactory.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization and Prediction of Continuous Cooling Transformations in Rail Steels

Rodrigues

Faria

2021

Mat. Res.

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“…Currently, there is an effort to reduce the heat-affected zone (HAZ) width of flash-butt welding [6][7][8]. Saita et al [8] showed a higher wear resistance at the softened region by narrowing the HAZ width.…”

Section: Introductionmentioning

confidence: 99%

“…Recent works [6,7] have also shown that the decrease in HAZ width leads to an improvement in the mechanical properties of Premium and Super Premium pearlitic rails.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Effect of Heat Input and Cooling Rate of Rail Flash-Butt Welding using Finite Element Method Simulation

et al. 2022

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Simulations using the finite element method (FEM) were done to understand the effects of heating/cooling rates on the distribution of residual stresses. Two material parameters from rails were used while the boundary conditions remained constant: heat-affected zone size, maximum temperature and heating extraction rate. To complement the analysis, a flash-butt weld of a Premium rail was done with welding parameters adjusted to obtain a narrow HAZ, without forced cooling, to examine the microstructure formed in the critical regions in the web and the edge of the rail foot. The results showed that there was a concentration of vertical residual stresses in the web region, while the presence of horizontal compression residual stresses was mostly superficial in the rail head region. The main result from the simulation sets was that when using two simulation parameters with similar materials (rails) substantially different results were obtained. Metallographic examinations showed that there was no presence of acicular microconstituents (martensite/bainite). In the rail web, proeutectoid ferrite was observed in the central region, cementite in a previous austenitic grain boundary, in the region that reached temperatures close to AC3, and almost complete spheroidization in the region of maximum spheroidization. In contrast, in the rail foot edge region, there was a completely pearlitic microstructure, in the central region and in the zone that reached temperatures close to AC3, and a lower volume of spheroidization in the region where maximum spheroidization is typically observed, probably due to the higher cooling rate in this region.

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Kinetics of Isothermal Phase Transformations in Premium and Standard Rail Steels

Rodrigues

Mourão

Faria

2020

steel research int.

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Recently published articles have enhanced the importance of understanding phase transformations in rail eutectoid steels in an attempt to improve their manufacturing and welding processes. Herein, the kinetics of isothermal phase transformations of three eutectoid steels used in railways around the world are evaluated. Computer simulations are performed to evaluate the effect of steel chemical compositions on phase transformations considering thermodynamic equilibrium conditions. Austenitizing temperatures under continuous heating and the time intervals of isothermal austenite decomposition are measured by dilatometry. The time–temperature–transformation diagrams are determined. Qualitative and quantitative microscopy techniques are applied to characterize the phase transformation products. It is shown that by applying a well‐planned heat treatment, it is possible to obtain microstructural characteristics for a standard steel as refined as those achieved for premium steels. Empirical equations proposed in the literature to predict the Bs temperatures are applied, and the experimental values are compared. Using the dilatometry data, it is possible to determine the global activation energy for austenite–bainite transformation. Results show that premium steels have higher overall activation energy for austenite–bainite decomposition than what occurs in standard. This article presents unpublished data useful for steel researchers as well for rail manufacturers and welders.

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The role of welding parameters on the control of the microstructure and mechanical properties of rails welded using FBW

Cited by 24 publications

References 11 publications

Characterization and Prediction of Continuous Cooling Transformations in Rail Steels

Characterization and Prediction of Continuous Cooling Transformations in Rail Steels

Evaluation of the Effect of Heat Input and Cooling Rate of Rail Flash-Butt Welding using Finite Element Method Simulation

Kinetics of Isothermal Phase Transformations in Premium and Standard Rail Steels

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