Extending the Boundaries of Mechanical Properties of Ti-Nb Low-Carbon Steel via Combination of Ultrafast Cooling and Deformation During Austenite-to-Ferrite Transformation

다국어 초록 (Multilingual Abstract)

We underscore here a novel approach to extend the boundaries of mechanical properties of Ti-Nb low-carbon steel via combination of ultrafast cooling and deformation during austenite-to-ferrite transformation.
The proposed approach yields a refined microstructure and high density nano-sized precipitates, with consequent increase in strength. Steels subjected to ultra-fast cooling during austenite-to-ferrite transformation led to 145 MPa increase in yield strength, while the small deformation after ultra-fast cooling process led to increase in strength of 275 MPa. The ultra-fast cooling refined the ferrite and pearlite constituents and enabled uniform dispersion, while the deformation after ultra-fast cooling promoted precipitation and broke the lamellar pearlite to spherical cementite and long thin strips of FexC. The contribution of nano-sized precipitates to yield strength was estimated to be ~247.9 MPa and ~358.3 MPa for ultrafast cooling and deformation plus ultrafast cooling processes. The nano precipitates carbides were identified to be (Ti, Nb)C and had a NaCl-type crystal structure, and obeyed the Baker-Nutting orientation relationship with the ferrite matrix.

참고문헌 (Reference)

1 N. J. Petch, 3 : 1089-, 1958

2 H. Kestenbach, 13 : 731-, 1997

3 M. Thompson, 41 : 891-, 2001

4 E. V. Pereloma, 210 : 16-, 1996

5 S. Shanmugam, 460-461 : 335-, 2007

6 R. D. K. Misra, 394 : 339-, 2005

7 G. D. Wang, 30 : 1-, 2008

8 Y. Tian, 55 : 1566-, 2012

9 X. Li, 47A : 1929-, 2016

10 B. Wang, 575 : 189-, 2013

11 X. T. Deng, 24 : 1072-, 2015

12 Y. Funakawa, 44 : 1945-, 2004

13 S. N. Prasad, 399 : 161-, 2005

14 R. M. Brito, 16 : 1257-, 1981

15 R. D. K. Misra, 34A : 2341-, 2003

16 Y. Ohmori, 11 : 339-, 1971

17 A. J. E. Foreman, 45 : 511-, 1967

18 Y. Funakawa, 93 : 49-, 2007

19 I. B. Timokhina, 56 : 601-, 2007

20 C. Y. Chen, 499 : 162-, 2009

21 H. W. Yen, 61 : 616-, 2009

22 H. W. Yen, 26 : 421-, 2010

23 J. H. Jang, 60 : 208-, 2012

24 S. G. Hong, 46 : 163-, 2002

25 C. Y. Chen, 499 : 162-, 2009

26 Z. Jia, 528 : 7077-, 2011

27 K. Kamibayashi, 52 : 151-, 2012

28 J. H. Jang, 29 : 309-, 2013

29 C. Y. Chena, 88 : 69-, 2014

30 N. Kamikawa, 54 : 212-, 2014

31 D. B. Park, 560 : 528-, 2013

32 R. Okamoto, 58 : 4783-, 2010

33 L. H. Friedman, 83 : 2715-, 1998

34 T. Gladman, "The Physical Metallurgy of Microalloyed Steels" Institute of Materials 39-, 1997

35 M. F. Ashby, "Strengthening Methods in Crystals" Applied Science Publishers Ltd 9-, 1971

36 Q. L. Yong, "Secondary Phases in Steels" Metallurgy Industry Press 8-, 2006

37 F. B. Pickering, "Physical Metallurgy and the Design of Steels" Applied Science Publishers Ltd 63-, 1978

38 K. Seto, "JFE Technical Report 10" JFE 19-, 2007