CARACTERIZAÇÃO DAS TRANSFORMAÇÕES DE FASES ISOTÉRMICAS E DOS SEUS RESPECTIVOS PRODUTOS EM TRES AÇOS EUTETÓIDES DE APLICAÇÃO FERROVIÁRIA
CHARACTERIZATION OF THE ISOTHERMAL PHASES TRANSFORMATIONS AND THE RESPECTIVES PRODUCTS IN THREE EUTECTOID STEELS FOR RAILROAD APPLICATION
Karine Fernandes Rodrigues, Gabriel Marques Magalhães Mourão, Geraldo Lúcio de Faria
Resumo
Artigos recentemente publicados vêm destacando a importância do conhecimento sobre a cinética de transformação de fases em aços eutetóides aplicados em ferrovias, visando o aprimoramento de processos de fabricação e de soldagem. Nesse sentido, o presente trabalho apresenta um estudo de caracterização da cinética de decomposição isotérmica da austenita em três aços atualmente utilizados no mundo para a fabricação de trilhos ferroviários, sendo dois de classificação premium e um de classificação standard. Os aços estudados foram caracterizados em seu estado de entrega e, por meio de ensaios de dilatometria, as temperaturas críticas de austenitização e os intervalos de tempo de decomposição da austenita foram medidos. Diagramas tempo-temperatura-transformação (TTT) foram determinados. A influência de alguns parâmetros como o espaçamento interlamelar perlítico original e o tamanho de grão austenítico prévio sobre as transformações de fases e sobre as microestruturas resultantes, foram discutidos. Mostrou-se ainda que, a partir de tratamentos isotérmicos bem planejados, é possível a obtenção de uma microestrutura majoritariamente bainítica em aços eutetoides com composições químicas relativamente simples.
Palavras-chave
Abstract
Recently published papers have been enhancing the importance of understanding about the kinetics of phase transformation in eutectoid steels applied to railways, aiming the improvement of the manufacturing and the welding processes. In this sense, this work presents a characterization study on the austenite’s isothermal decomposition kinetics in three steels currently used worldwide in the manufacturing of railway tracks, being two of then premium and the other standard. The steels studied were characterized at initial state and, through dilatometry, the austenitization critical temperatures and the austenite decomposition’s time intervals were measured. Time-temperature-transformation (TTT) diagrams were determined. The influence of some parameters such as the original pearlite interlamellar spacing and the prior austenitic grain’s size on the phase transformations and the resulting microstructures, was discussed. The study also showed that stemming from well-planned isothermal treatments, it is possible to obtain a mostly-bainitic microstructure in eutectoid steels of fairly simple chemical compositions.
Keywords
Referências
1 Sahay SS, Mohapatra GT. Overview of pearlitic rail steel: accelerated cooling, quenching, microstructure, and mechanical properties. Journal of ASTM International. 2009;6(7):1-25.
2 Porcaro RR, Faria GL, Godefroid LB, Apolonio GR, Candido LC, Pinto ES. Microstructure and mechanical properties of a flash buttwelded pearlitic rail. Materials Processing Technology. 2019;270:20-27. http://dx.doi.org/10.1016/j.jmatprotec.2019.02.013.
3 Nishikawa LP, Goldenstein H. Divorced eutectoid on heat-affected zone of welded pearlitic rails. The Journal of The Minerals, Metals & Materials Society (TMS). 2019;71(2):815-823. https://doi.org/10.1007/s11837-018-3213-5.
4 Taleff EM, Lewandowski JJ, Pourladian B. Microstructure-property relationships in pearlitic eutectoid and hypereutectoid carbon steels. Journal of The Minerals, Metals & Materials Society (TMS). 2002;54(7):25-30. http://dx.doi.org/10.1007/BF02700982.
5 Offerman SE, van Wilderen LJGW, van Dijk NH, Sietsma J, Rekveldt MT, van der Zwaag S. In-situ study of pearlite nucleation and growth during isothermal austenite decomposition in nearly eutectoid steel. Acta Materialia. 2003;51(13):3927-3938. http://dx.doi.org/10.1016/S1359-6454(03)00217-9.
6 Pickering FB. Physical metallurgy and the design of steels. USA: Applied Sciences Publishers; 1978. p. 90-100.
7 Wang M, Zhang F, Yang Z. Effects of high-temperature deformation and cooling process on the microstructure and mechanical properties of an ultrahigh-strength pearlite steel. Materials & Design. 2017;114:102-110. http://dx.doi.org/10.1016/j.matdes.2016.10.049.
8 Marder AR, Bramfitt BL. The effect of morphology on the strength of pearlite. Metallurgical Transactions. A, Physical Metallurgy and Materials Science. 1976;7(3):365-372. http://dx.doi.org/10.1007/BF02642832.
9 Hyzak JM, Bernstein IM. The role of microstructure on the strength and toughness of fully pearlitic steels. Metallurgical Transactions. A, Physical Metallurgy and Materials Science. 1976;7(8):1217-1224. http://dx.doi.org/10.1007/BF02656606.
10 Dollar M, Bernstein IM, Thompson AW. Influence of deformation substructure on flow and fracture of fully pearlitic steel. Acta Metallurgica. 1988;36(2):311-320. http://dx.doi.org/10.1016/0001-6160(88)90008-9.
11 Godefroid LB, Moreira LP, Vilela TCG, Faria GL, Candido LC, Pinto ES. Effect of chemical composition and microstructure on the fatigue crack growth resistance of pearlitic steels for railroad application. International Journal of Fatigue. 2019;120:241-253. http://dx.doi.org/10.1016/j.ijfatigue.2018.10.016.
12 Farhangi H, Mousavizadeh SM. Horizontal split-web fractures of flash butt welded rails. In: Proceedings of the 8th International Fracture Conference; 2007; Istanbul, Turkish. Istanbul. p. 509-517.
13 Tawfik D, Mutton PJ, Chiu WK. Transient thermal stress analysis on rapid post-weld heat treatments applied to flash butt welded rails. Science and Technology of Welding and Joining. 2006;11(3):326-336. http://dx.doi.org/10.1179/174329306X107629.
14 American Railway Engineering and Maintenance-of-Way Association. Manual for railway engineering. Lanham, Maryland: AREMA; 2013.
15 Lee KM, Polycarpou AA. Wear of conventional pearlitic and improved bainitic rail steels. Wear. 2005;259(1-6):391- 399. http://dx.doi.org/10.1016/j.wear.2005.02.058.
16 Aglan HA, Liu ZY, Hassan MF, Fateh M. Mechanical and fracture behavior of bainitic rail steel. Journal of Materials Processing Technology. 2004;151(1-3):268-274. http://dx.doi.org/10.1016/j.jmatprotec.2004.04.073.
17 American Society for Testing and Materials. ASTM E3: Standard Guide for Preparation of Metallographic Specimens. West Conshohocken: ASTM; 2017.
18 American Society for Testing and Materials. ASTM E112: Standard Test Methods for Determining Average Grain Size. West Conshohocken: ASTM; 2014.
19 Silva PRT. Caracterização de trilhos ferroviários quanto a tenacidade à fratura e comportamento em fadiga. [dissertação]. Porto Alegre: Universidade Federal do Rio Grande do Sul; 1995.
20 Gomes MGMF, Almeida LH, Gomes LCFC, May IL. Effects of microstructural parameters on the mechanical properties of eutectoid rail steels. Materials Characterization. 1997;39(1):1-14. http://dx.doi.org/10.1016/S1044-5803(97)00086-7.
21 Limberger IF. Estudo da propagação de trincas transversais por fadiga em trilhos ferroviários [tese]. Porto Alegre: Universidade Federal do Rio Grande do Sul; 2000.
22 American Society for Testing and Materials. ASTM E1382: Standard Test Methods for Determining Average Grain Size Using Semiautomatic and Automatic Image Analysis. West Conshohocken: ASTM; 2015.
23 Clayton P, Devanathan R. Rolling/sliding wear behavior of a chromium- molybdenum rail steel in pearlitic and bainitic conditions. Wear. 1992;156(1):121-131. http://dx.doi.org/10.1016/0043-1648(92)90148-2.
24 Olivares RO, Garcia CI, Deardo A, Kalay S, Hernández FCR. Advanced metallurgical alloy design and thermomechanical processing for rails steels for North American heavy haul use. Wear. 2011;271(1-2):364-373. http://dx.doi.org/10.1016/j.wear.2010.10.048.
25 Gladman T, Mclvor ID, Pickering FB. Some aspects of the structure – property relationship in high-carbon ferritepearlite steels. ISIJ International. 1972:916-930.
26 Moreira LP. Efeito de características microestruturais na tenacidade à fratura e no crescimento de trinca por fadiga de aços perlíticos de aplicação ferroviária [dissertação] Ouro Preto: Rede Temática em Engenharia de Materiais, Universidade Federal de Ouro Preto; 2015.
27 Krauss G. Processing, structure, and performance. Ohaio: ASM International; 2005.
28 Andrés CG, Caballero FG, Capdevila C, Álvarez LF. Application of dilatometric analysis to the study of solid-solid phase transformations in steels. Materials Characterization. 2002;48(1):101-111. http://dx.doi.org/10.1016/S1044- 5803(02)00259-0.
29 Caballero FG, Capdevila C, Andrés CG. Influence of scale parameters of pearlite on the kinetics of anisothermal pearlite-to-austenite transformation in a eutectoid steel. Scripta Materialia. 2000;42(12):1159-1165. http://dx.doi.org/10.1016/S1359-6462(00)00352-3.
30 Roosz A, Gacsi Z, Fuchs EG. Isothermal formation of austenite in eutectoid plain carbon steel. Acta Metallurgica. 1983;31(4):509-517. http://dx.doi.org/10.1016/0001-6160(83)90039-1.
31 Jacot A, Rappaz M, Reed RC. Modelling of reaustenitization from the perlite structure in steel. Acta Metallurgica. 1998;46(11):3949-3962.
32 Caballero FG, Capdevila C, Andrés CG. Modelling of isothermal formation of pearlite and subsequent reaustenitisation in eutectoid stell during continuous heating. Materials Science and Technology. 2001;17(6):686-692. http://dx.doi.org/10.1179/026708301101510401.
33 Zhang G, Chae J, Kim K, Suh DW. Effects of Mn, Si and Cr addition on the dissolution and coarsening of pearlitic cementite during intercritical austenitization in fe-1mass% alloy. Materials Characterization. 2013;81:56-67. http://dx.doi.org/10.1016/j.matchar.2013.04.007.
34 Miyamoto G, Usuki H, Li Z-D, Furuhara T. Effects of Mn, Si and Cr addition on reverse transformation at 1073K from spheroidized cementite structure in Fe-0.6 mass% C alloy. Acta Materialia. 2010;58(13):4492-4502. http://dx.doi.org/10.1016/j.actamat.2010.04.045.
35 Karmazin L, Krejci J. The dependence of the austenitization kinetics on the type of initial spheroidized structure in low alloy steel. Materials Science and Engineering. 1994;185(1-2):5-7. http://dx.doi.org/10.1016/0921- 5093(94)90944-X.
36 Pawlowski B, Bala P, Dziurka R. Improper interpretation of dilatometric data for cooling transformations in steels. Arquives of Metallurgy and Materials. 2014:1159-1161. http://dx.doi.org/10.2478/amm-2014-0202.
37 Wang L, Wang Z, Lu K. Grain size effects on the austenitization process in a nanostructured ferritic steel. Acta Materialia. 2011;59(9):3710-3719. http://dx.doi.org/10.1016/j.actamat.2011.03.006.
38 Zhao JC, Notis MR. Continuous cooling transformation kinetics versus isothermal transformation kinetics of steels: a phenomenological rationalization of experimental observations. Materials Science and Engineering. 1995;15(4-5):135-207. http://dx.doi.org/10.1016/0927-796X(95)00183-2. 39 Prakash AK, Brimacombe JK. Mathematical model of heat flow and austenite-perlite transformation in eutectoid carbon steel rods for wire. Metallurgical Transactions. B, Process Metallurgy. 1981;12(1):121-133.
40 Brooks CR. Principles of the austenitization of steels. London: Elsevier Science; 1992.
41 Seol JB, Raabe D, Choi PP, Im YR, Park CG. Atomic scale effects of alloying, partitioning, solute drag and austempering on the mechanical properties of high-carbon bainitic–austenitic TRIP steels. Acta Materialia. 2012;60(17):6183-6199. http://dx.doi.org/10.1016/j.actamat.2012.07.064.
42 Vicente FA, Carsí M, Penãlba F, Taleff E, Ruano OA. Toughness dependence on the microstructural parameters for an ultrahigh carbon steel (1.3 wt.% C). Materials Science and Engineering. 2001;335(1-2):175-185.
43 Lewandowski JJ, Thompson AW. Effects of the prior austenite grain size on the ductility of fully pearlitic eutectoid steel. Metallurgical Transactions. A, Physical Metallurgy and Materials Science. 1986;17(3):461-472. http://dx.doi.org/10.1007/BF02643953.
44 Puls MP, Kirkaldy JS. The pearlite reaction. Metallurgical Transactions. 1972;3(11):2777-2796. http://dx.doi.org/10.1007/BF02652844.
45 Steele RK. Steel alloys with lower bainite microstructures for use in railroad cars and track. USA: U.S. Department of Transportation; 2002.
Facebook
Google+
Twitter
LinkedIn
Mendeley
StumbleUpon
CiteULike
Reddit
Email