Effect of Cooling and Isothermal Holding on the Amount of Martensite/Austenite (M/A) Constituents, Microstructure and Mechanical Properties of Microalloyed Pipeline Steel

Abstract:

Constant increase of energy consumption in modern industry requires construction of heavily loaded pipelines with high throughput capacity. Therefore, high-strength steels should be used for the cost reasons. Additionally, the pipelines are also often used in the areas with cold climate and high seismicity. Therefore, strength and plasticity reduction is unacceptable. Bainitic steels with retained austenite (RA) or martensite/austenite (M/A) constituents meet these requirements. The purpose of this investigation is to determine thermo-mechanical treatment parameters with further accelerated cooling and additional isothermal holding for M/A-phase and mechanical properties formation. Experimental modeling of the production process was carried out using Gleeble HDS-V40 thermo-mechanical simulator. All investigations were realized with two high-strength micro-alloyed steels with different molybdenum and carbon content. Results showed that decrease of temperature and duration of isothermal holding as well as addition of molybdenum promote bainitic microstructure nucleation and reduce grain size and M/A-constituents. All these factors lead to a slight improvement in mechanical properties.

• Periodical: Materials Science Forum (Volume 918)
• Pages: 152-158
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.918.152
• Online since: March 2018
• Authors: Alexander Kabanov*, Grzegorz Korpala, Rudolf Kawalla, Sergey Ionov
• Keywords: Bainite with Retained Austenite, Heavy Plate, Martensite-Austenite Phase (MA Phase), Pipeline Steel, Thermo-Mechanical Treatment

References

[1] H. -G. Hillenbrand, A. Liessem, K. Biermann, C.J. Heckmann, V. Schwinn, Development of High Strength Material and Pipe Production Technology for Grade X120 Line Pipe, in: 2004 International Pipeline Conference, Volumes 1, 2, and 3, ASME, 2004, p.1743.

DOI: 10.1115/ipc2004-0224

[2] T. Shinmiya, N. Ishikawa, M. Okatsu, S. Endo, N. Shikanai, J. Kondo, others, Development of high deformability linepipe with resistance to strain-aged hardening by heat treatment on-line process, in: The Seventeenth International Offshore and Polar Engineering Conference, (2007).

DOI: 10.1115/omae2005-67149

[3] A. Kabanov, G. Korpala, R. Kawalla, S. Ionov, Effect of Hot Rolling and Thermal Treatment on the Microstructure Evolution of Microalloyed Bainitic Steels for Pipeline, KEM 746 (2017) 176–183.

DOI: 10.4028/www.scientific.net/kem.746.176

[4] M. Okatsu, N. Shikanai, J. Kondo, Development of a High-Deformability Linepipe with Resistance to Strain-aged Hardening by HOP\textregistered(Heat-treatment On-line Process), JFE Technical Report 12 (2008) 8–13.

[5] C. Wang, X. Wu, J. Liu, N. Xu, Transmission electron microscopy of martensite/austenite islands in pipeline steel X70, Materials Science and Engineering: A 438 (2006) 267–271.

DOI: 10.1016/j.msea.2006.02.118

[6] H.K. Sung, D.H. Lee, S.Y. Shin, S. Lee, J.Y. Yoo, B. Hwang, Effect of finish cooling temperature on microstructure and mechanical properties of high-strength bainitic steels containing Cr, Mo, and B, Materials Science and Engineering: A 624 (2015).

DOI: 10.1016/j.msea.2014.11.035

[7] L. -n. Duan, C. Yu, Q. -y. Liu, S. -j. Jia, C. -c. Jia, Microstructures and Mechanical Properties of X100 Pipeline Steel Strip, Journal of Iron and Steel Research, International 21 (2014) 227–232.

DOI: 10.1016/s1006-706x(14)60035-2

[8] H.F. Lan, L.X. Du, X.H. Liu, Microstructure and Mechanical Properties of a Low Carbon Bainitic Steel, steel research international 84 (2013) 352–361.

DOI: 10.1002/srin.201200186

[9] J. Kong, C. Xie, Effect of molybdenum on continuous cooling bainite transformation of low-carbon microalloyed steel, Materials & design 27 (2006) 1169–1173.

DOI: 10.1016/j.matdes.2005.02.006

[10] V. Biss, R.L. Cryderman, Martensite and retained austenite in hot-rolled, low-carbon bainitic steels, Metallurgical and Materials Transactions B 2 (1971) 2267–2276.

DOI: 10.1007/bf02917559

[11] S. Zajac, V. Schwinn, K.H. Tacke, Characterisation and quantification of complex bainitic microstructures in high and ultra-high strength linepipe steels, in: Materials Science Forum, 2005, p.387–394.

DOI: 10.4028/www.scientific.net/msf.500-501.387

[12] H.K. Sung, S. Lee, S.Y. Shin, Effects of Start and Finish Cooling Temperatures on Microstructure and Mechanical Properties of Low-Carbon High-Strength and Low-Yield Ratio Bainitic Steels, Metallurgical and Materials Transactions A 45 (2014).

DOI: 10.1007/s11661-013-2156-2