등온 열처리에 따른 중탄소 베이나이트강의 미세조직과 기계적 특성

이지민; 이상인; 임현석; 황병철; Ji-Min Lee; Sang-In Lee; Hyeon-Seok Lim; Byoungchul Hwang

Korean Journal of Materials Research, Vol.28, No.9, 522-527, September, 2018

DOI10.3740/MRSK.2018.28.9.522 Export Citation

등온 열처리에 따른 중탄소 베이나이트강의 미세조직과 기계적 특성

Effect of Isothermal Heat Treatment on the Microstructure and Mechanical Properties of Medium-Carbon Bainitic Steels

이지민, 이상인, 임현석, 황병철 ^†

서울과학기술대학교 신소재공학과

Ji-Min Lee, Sang-In Lee, Hyeon-Seok Lim, and Byoungchul Hwang^†

Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea

E-mail:

This study investigates the effects of isothermal holding temperature and time on the microstructure, hardness and Charpy impact properties of medium-carbon bainitic steel specimens. Medium-carbon steel specimens with different bainitic microstructures are fabricated by varying the isothermal conditions and their microstructures are characterized using OM, SEM and EBSD analysis. Hardness and Charpy impact tests are also performed to examine the correlation of microstructure and mechanical properties. The microstructural analysis results reveal that granular bainite, bainitic ferrite, lath martensite and retained austenite form differently in the specimens. The volume fraction of granular bainite and bainitic ferrite increases as the isothermal holding temperature increases, which decreases the hardness of specimens isothermally heat-treated at 300 °C or higher. The specimens isothermally heat-treated at 250 °C exhibit the highest hardness due to the formation of lath martensite, irrespective of isothermal holding time. The Charpy impact test results indicate that increasing isothermal holding time improves the impact toughness because of the increase in volume fraction of granular bainite and bainitic ferrite, which have a relatively soft microstructure compared to lath martensite for specimens isothermally heat-treated at 250 °C and 300 °C.

Keywords:medium carbon;bainitic steels;isothermal heat treatment;microstructure;mechanical properties

[References]

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Zhang F, Yang Z, Kang J, J. Yanshan University, 1, 2 (2013)
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Zhou M, Xu G, Hu H, Yuan Q, Tian J, Met. Mater. Int., 24, 28 (2018)
Tian J, Xu G, Jiang Z, Hu H, Zhou M, Met. Mater. Int., 29 April 2018 [Epub]. https://doi.org/10.1007/s12540-018-0139-y.
Zhang S, Wang P, Li D, Li Y, Mater. Des., 84, 385 (2015)
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Garcia-Mateo C, Sourmail T, Caballero FG, Smanio V, Ziegler MKC, Leiro A, Vuorinen E, Elvira R, Teeri T, Mater. Sci. Technol., 30, 1071 (2014)
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Xiong XC, Chen B, Huang MX, Wang JF, Wang L, Scr. Mater., 68, 321 (2013)
Soliman M, Palkowski H, ISIJ Int., 47, 1703 (2007)
Huang H, Sherif MY, Rivera-Diaz-del-Castillo PEJ, Acta Mater., 61, 1639 (2013)
Lim HS, Lee JM, Song YB, Kim HK, Hwang BC, Korean J. Mater. Res., 27(7), 357 (2017)
Long XY, Kang J, Lv B, Zhang FC, Mater. Des., 64, 237 (2014)
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Lee JM, Han JJ, Song YB, Ham JH, Kim HK, Hwang B, Korea J. Mater. Res., 28, 459 (2018)

[Related Articles]

[1] Sandvik BPJ, Nevalainen HP, Mater. Sci. Technol., 8, 213 (1981)

[2] Bhadeshia HKDH, Edmonds DV, Mater. Sci. Technol., 17, 411 (1983)

[3] Caballero FG, Santofimia MJ, Garcia-Mateo C, Chao J, Andres CG, Mater. Des., 30, 2077 (2009)

[4] Chakraborty J, Bhattacharjee D, Mannaa I, Scr. Mater., 59, 247 (2008)

[5] Kalker JJ, Cannon DF, Orringer O, p.454, Kluwer Academic, Alphen aan den Rijn, Netherlands (1993).

[6] Pointner P, Wear, 265, 1373 (2008)

[7] Zhang F, Yang Z, Kang J, J. Yanshan University, 1, 2 (2013)

[8] Hu H, Xu G, Zhou M, Yuan Q, Met. Mater. Int., 23, 233 (2017)

[9] Zhou M, Xu G, Hu H, Yuan Q, Tian J, Met. Mater. Int., 24, 28 (2018)

[10] Tian J, Xu G, Jiang Z, Hu H, Zhou M, Met. Mater. Int., 29 April 2018 [Epub]. https://doi.org/10.1007/s12540-018-0139-y.

[11] Zhang S, Wang P, Li D, Li Y, Mater. Des., 84, 385 (2015)

[12] Garcia-Mateo C, Caballero FG, Sourmail T, Smanio V, Andres CG, Int. J. Mater. Res., 105, 725 (2014)

[13] Garcia-Mateo C, Sourmail T, Caballero FG, Smanio V, Ziegler MKC, Leiro A, Vuorinen E, Elvira R, Teeri T, Mater. Sci. Technol., 30, 1071 (2014)

[14] Zhou YX, Song XT, Liang JW, Shen YF, Misra RDK, Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process., 718, 267 (2018)

[15] Shen YF, Qiu LN, Sun X, Zuo L, Liaw PK, Raabe D, Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process., 636, 551 (2015)

[16] Choi KS, Soulami A, Liu WN, Sun X, Khaleel MA, Comput. Mater. Sci., 50, 720 (2010)

[17] Xiong XC, Chen B, Huang MX, Wang JF, Wang L, Scr. Mater., 68, 321 (2013)

[18] Soliman M, Palkowski H, ISIJ Int., 47, 1703 (2007)

[19] Huang H, Sherif MY, Rivera-Diaz-del-Castillo PEJ, Acta Mater., 61, 1639 (2013)

[20] Lim HS, Lee JM, Song YB, Kim HK, Hwang BC, Korean J. Mater. Res., 27(7), 357 (2017)

[21] Long XY, Kang J, Lv B, Zhang FC, Mater. Des., 64, 237 (2014)

[22] Dieter GE, Mechanical Metallurgy, p.800, McGraw-Hill Education, New York, USA (2001).

[23] Hertzberg RW, John Wiley & Sons Inc., New Jersey, USA 1996.

[24] Lee JM, Han JJ, Song YB, Ham JH, Kim HK, Hwang B, Korea J. Mater. Res., 28, 459 (2018)