Abstract
The structures produced in a Nb-microalloyed steel by oil quenching after intercritical anneals at 760 and 810 °C have been examined by light and transmission electron microscopy. After both anneals, the periphery of the austenite pool transforms on cooling to ferrite in the same orientation as the ferrite retained during intercritical annealing. Thus the ferrite forms by an epitaxial growth mechanism without the formation of a new interface or grain boundary. The new ferrite is precipitate-free in contrast to the retained ferrite which develops a very dense precipitate dispersion during intercritical annealing. In the carbonenriched interior of the austenite pool beyond the epitaxial ferrite only martensite forms in specimens annealed at 760 °C but various mixtures of ferrite and cementite form in specimens annealed at 810 °C. The latter structures include lamellar pearlite, a degenerate pearlite, and cementite interphase precipitation. All Nb is in solution in the austenite formed at 810 °C, and therefore the low hardenability of the specimens annealed at that temperature is best explained by the effect of low austenite carbon content.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
David K. Matlock, George Krauss, Luis F. Ramos, and Glenn S. Huppi:Structure and Properties of Dual-Phase Steels, R. A. Kot and J. W. Morris, eds., pp. 62–90, TMS-AIME, Warrendale, PA, 1979.
M. S. Rashid: Automotive Engineering Congress, Rep. No. 760206, Detroit, Soc. Auto. Engineers, 1976.
R. G. Davies:Met. Trans. A, 1978, vol. 9A, pp. 41–52.
A. P. Coldren, G. Tither, A. Cronford, and J. R. Hiam:Formable HSLA and Dual-Phase Steels, A. T. Davenport, ed., pp. 205–26, TMS-AIME, Warrendale, PA, 1979.
P. R. Mould and C. C. Skena:Formable HSLA and Dual-Phase Steels, A. T. Davenport, ed., pp. 181–204, TMS-AIME, Warrendale, PA, 1979.
Richard D. Lawson, David K. Matlock, and George Krauss:Metallography, 1980, vol. 13, pp. 71–87.
I. H. Khan:Handbook of Thin Film Technology, L. I. Maissel and R. Glang, eds., pp. 10–13, McGraw-Hill, Inc., New York, 1970.
M. A. Grossman and E. C. Bain:Principals of Heat Treatment, 5th ed., ASM, Metals Park, OH, 1964.
C. A. Siebert, D. V. Doane, and D. H. Breen:The Hardenability of Steels, ASM, Metals Park, OH, 1977.
G. T. Eldis and W. C. Hagel:Hardenability Concepts with Applications to Steel, D. V. Doane and J. S. Kirkaldy, eds., pp. 397–413, AIME, Warrendale, PA, 1978.
A. T. Davenport, L. C. Brossard, and R. E. Miner:J. Met., June 1975, vol. 27, pp. 21–7.
P. L. Mangonon, Jr. and W. E. Heitmann:Microalloying ’75, pp. 59–74, Union Carbide Corporation, New York, 1977.
T. M. Hagendoorn and M. J. Spanraft:Microalloying ’75, pp. 75–85, Union Carbide Corporation, New York, 1977.
J. M. Gray:Processing and Properties of Low-Carbon Steel, J. M. Gray, ed., pp. 225–42, AIME, Warrendale, PA, 1973.
M. Cohen and S. S. Hansen: ASTM STP 672, pp. 34–52, American Society for Testing and Materials, Philadelphia, PA, 1979.
R. W. K. Honeycombe:Met. Trans. A, 1976, vol. 7A, pp. 915–36.
L. Meyer, F. Heisterkamp, and W. Mueshenborn:Microalloying ’75, pp. 153–67, Union Carbide Corporation, New York, 1977.
E. L. Brown, A. J. DeArdo, and J. H. Bucher:The Hot Deformation of Austenite, pp. 250–85, AIME, 1977.
T. Sakai, M. Shiozaki, and K. Takashina:J. Appl. Phys., 1979, vol. 50, pp. 2369–71.
N. C. Law and D. V. Edmonds:Met. Trans. A, 1980, vol. 11 A, pp. 33–6.
A. T. Davenport and P. C. Becker:Met. Trans., 1971, vol. 2, pp. 2962–64.
J. M. Gray and R. B. G. Yeo:ASM Trans. Q., 1968, vol. 61, pp. 255–69.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Geib, M.D., Matlock, D.K. & Krauss, G. The effect of intercritical annealing temperature on the structure of niobium microalloyed dualphase steel. Metall Trans A 11, 1683–1689 (1980). https://doi.org/10.1007/BF02660523
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02660523