Effect of Chromium and Nickel Additions on the Transformation Characteristic and Ferrite Grain Size Refinement of Low Carbon Structural Steels Containing 0.13% C

Abstract:

The effect of small addition of chromium and nickel alone or in combination on the transformation characteristic and ferrite grain size of low carbon (0.13%C) structural steels have been studied by cooling suitable steels at four different cooling rates ranging from 120°C/min to 3.6° C/min from temperatures giving a constant austenite grain size of 37 μm. Radio Frequency generator with control system was used for the heat treatment of the steel samples. Optical microscopy of the heat treated samples was carried out. Ferrite grain size was determined from the fictitious ferrite grain size measured by mean linear intercept method and the volume fraction of pearlite obtained by optical microscopy and point counting. It was found that although the heat treatment of the steels was started from a common austenite grain size, their subsequent ferrite grain size after cooling at the same cooling rate were not the same. Both chromium and nickel enhance the formation of Widmanstatten structure. But chromium is more effective than nickel in the formation of Widmanstatten structure. It was also found that the undissolved particles of chromium carbide (Cr₂C) present during austenitizing have no role in determining the ferrite grain size. The precipitating particles of chromium carbide (Cr₂C) are excellent ferrite grain size refiners. Nickel refines the ferrite grain size. In presence of nickel, Cr2C precipitates are less effective than Cr₂C precipitates in absence of nickel in the refinement of ferrite grain size.

• Periodical: Applied Mechanics and Materials (Volume 860)
• Pages: 158-164
• DOI: https://doi.org/10.4028/www.scientific.net/AMM.860.158
• Online since: December 2016
• Authors: Md Mohar Ali Bepari*, Mohiuddin Ahmed
• Keywords: Chromium Addition, Chromium Carbide Precipitates, Constant Austenite Grain Size, Cooling Rate, Ferrite Grain Size, Mean Linear Intercept, Nickel Addition, Pearlite Volume Fraction, Radio Frequency Generator, Structural Steel, Widmanstätten Structure

References

[1] E. O. Hall, Proc. Phys. Soc., 1951, Series B, 64, p.747.

[2] N. J. Petch, J.I.S.I., 1953, 174, p.25.

[3] N. J. Petch, Swampscott conf., 1959, M.I.T. Press, p.54.

[4] H. J. Wiester, H.A. Vogles, and H. Ulmer, Stahlund Eisen, 1959, 79, No. 16, 1120.

[5] W. B. Morrison, J. Iron Steel Inst., 1963, 201, 317.

[6] D. Websterand J. H. Woodhead, J. Iron steel Inst., 1964, 202, pp.987-994.

[7] K. J, Irvine and F. B. Pickering, J. Iron steel Inst., 1963, 201, 987.

[8] K. J. Irvine, F.B. Pickering, and T. Gladman, J.I.S.I., 1967, 205, p.161.

[9] F. B. Pickering, and T. Gladman, Metallurgical Development in Carbon Steels, I.S.I. Special Report, 1963, 81, p.10.

[10] M. M. A. Bepari, 1981, Ph. D. Thesis, University of Sheffield, U. K.

[11] M. M. A. Bepari, Materials Science and Technology, Jan, 1989, (5), p.13.

[12] M. Z. Hoque, M. Sc. Engineering Thesis, 1989, Dept. of Materials and Metallurgical Engineering, BUET, Dhaka.

[13] M. A. Rahman, M. Sc. Engineering Thesis, 1998, Dept. of Materials and Metallurgical Engineering, BUET, Dhaka.

[14] M. A, Rahman and M .M. A., Bepari, Proceedings of the International Conference on Advances in Materials and Processing Technology (AMPT 2009), 26-29 October, 2009, Kuala Lumpur, Malaysia.

[15] M. Ahmed, M.M.A. Bepari, R.H. Galib, Proceeding of the International conference on International Conference on Materials and Manufacturing Engineering (ICMME-2015), 25-27 December, 2015, Dhaka, Bangladesh.