The effects of auto-tempering martensite on mechanical strength of a microalloyed steel containing boron and titanium
Wagner Monteiro de Souza, André Itman Filho, Rosana Vilarim da Silva, João Batista Ribeiro Martins, Luciana Xavier da Cruz Lima
Oil Country Tubular Goods (OCTG) steels are used in the form of tubes in the casing column of the oil well walls and exhibit tempered martensitic structure after quenching and tempering. In these steels, due to the high cost of chromium, nickel and molybdenum, an alternative is the replacement of these elements by boron, which increases the hardenability. In order to maintain the efficiency of boron in solution during the quenching, it is necessary to add titanium to form titanium nitrides (TiN), which inhibit austenitic grain growth and avoid the formation of boron nitride. Another factor is to evaluate the effect of heat treatment on the mechanical properties of this steel. In the present study were evaluated the microstructure, hardness and tensile properties of a microalloyed hot rolled steel containing boron and titanium after heat treatments. Samples of a coil were quenched at 850 and 1050°C and then tempered at 200 and 600°C. The results show that the hardness, yield stress and tensile strength after austenitization temperature at 1050°C are smaller, due to the formation of auto-tempering martensite in the quenching.
1 Li C, Yuan G, Ji F, Ren D, Wang G. Effects of auto-tempering on microstructure and mechanical properties in hot rolled plain C-Mn dual phase steels. Materials Science and Engineering A. 2016;665:98-107.
2 Ohlund CEIC, Schlangen E, Erik Offerman S. The kinetics of softening and microstructure evolution of martensite in Fe-C-Mn steel during tempering at 300°C. Materials Science and Engineering A. 2013;560:351-357.
3 Kamp A, Celotto S, Hanlon DN. Effects of tempering on the mechanical properties of high strength dual-phase steels. Materials Science and Engineering A. 2012;538:35-41. http://dx.doi.org/10.1016/j.msea.2012.01.008.
4 Gündüz S. Static strain ageing behaviour of dual phase steels. Materials Science and Engineering A. 2008;486(1-2):63-71. http://dx.doi.org/10.1016/j.msea.2007.08.056.
5 Ghali SN, El-Faramawy HS, Eissa MM. Influence of boron additions on mechanical properties of carbon steel. Scientif Research. 2012;11(10):995-999.
6 Panigrahi BK. Processing of low carbon steel plate and hot strip. Bulletin of Materials Science. 2001;24(4):361-371. http://dx.doi.org/10.1007/BF02708632.
7 Cruz JA Jr, Santos DB. Effect of tempering temperature on isothermal decomposition product formed below Ms. Journal of Materials Research and Technology. 2013;2(2):93-99. http://dx.doi.org/10.1016/j.jmrt.2012.11.001.
8 Shen Y, Hansen SS. Effect of the Ti/N ratio on the hardenability and mechanical properties of a Quenched-andTempered C-Mn-B steel. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science. 1997;28(10):2027-2035.
9 Frantov II, Golovanenko SA, Moiseev BA, Burnyashev II. Effect Influence of heat treatment on the effectiveness of microalloying of pipe steels. Metallovedenie i Termicheskaya Obrabotka Metallov. 1980;(11):51-54.
10 Kasatkin OG, Vinokur BB, Pilyushenko VL. Calculation models for determining the critical points of steel. Metal Science and Heat Treatment. 1984;26(1):27-31.
11 Matsuda H, Mizuno R, Funakawa Y, Seto K, Matsuoka S, Tanaka Y. Effects of auto-tempering behaviour of martensite on mechanical properties of ultra high strength steel sheets. Journal of Alloys and Compounds. 2013;577:661-667.
12 Nishibata T, Kojima N. Effect of quenching rate on hardness and microstructure of hot stamped steel. Journal of Alloys and Compounds. 2013;577:S549-S554. http://dx.doi.org/10.1016/j.jallcom.2011.12.154.
13 Speich GR, Leslie WC. Tempering of steel. Metallurgical Transactions. 1972;3(5):1043-1054.
14 Reed-Hill RE. Physical metallurgy principles. 4th ed. Stamford: Cengage Learning; 2009.
15 Cuddy LJ, Raley JC. Austenite grain coarsening in microalloyed steels. Metallurgical Transactions. A, Physical Metallurgy and Materials Science. 1983;14(10):1989-1995.
16 Gladman T. Precipitation hardening in metals. Materials Science and Technology. 1999;15(1):30-36.
17 Itman A, Silva RV, Souza WM, Martins JB, Casteletti LC, Totten GE. Effect of quenching and tempering in microalloyed steels containing boron and titanium. In: Proceedings of the 23rd International Federation of Heat Treatment and Surface Engineering Congress, 2016; Savannah, GA, USA. Materials Park: ASM; 2016. p. 536-540.
18 Korchynsky M. Application of titanium-nitride for grain refinement. In: Proceedings of the 35th Mechanical Working and Steel Processing Conference; 1993; Pittsburgh, PA, USA. Pittsburgh: ISS; 1993.