Abstract
The effects of controlled rolling on transformation behavior of two powder forged (P/F) microalloyed vanadium steels and a cast microalloyed vanadium steel were investigated. Rolling was carried out in the austenitic range below the recrystallization temperature. Equiaxed grain structures were produced in specimens subjected to different reductions and different cooling rates. The ferrite grain size decreased with increasing deformation and cooling rate. Ferrite nucleated on second phase particles, deformation bands, and on elongated prior austenite grain boundaries; consequently a high fractional ferrite refinement was achieved. Deformation raised the ferrite transformation start temperature while the time to transformation from the roll finish temperature decreased. Cooling rates in the cast steel were higher than in P/F steels for all four cooling media used, and the transformation start temperatures of cast steels were lower than that of P/F steel. Intragranular ferrite nucleation, which played a vital role in grain refinement, increased with cooling rate. Fully bainitic microstructures were formed at higher cooling rates in the cast steel. In the P/F steels inclusions and incompletely closed pores served as sites for ferrite nucleation, often forming a ‘secondary’ ferrite. The rolling schedule reduced the size of large pores and particle surface inclusions and removed interconnected porosity in the P/F steels.
Similar content being viewed by others
References
G. R. Speich and R. L. Miller:Structure and Properties of DualPhase Steels, AIME, Warrendale, PA, 1979, pp. 145–82.
E. L. Brown, A. J. DeArdo, and J. H. Bucher:The Hot Deformation ofAustenite, AIME publ., 1977, pp. 250–85.
H. J. McQueen and J. J. Jonas:Treatise on Materials Sci. and Tech., vol. 6, “Plastic Deformation of Materials,” Academic Press, New York, NY, 1975, pp. 393–493.
M. Cohen and W. S. Owen:Microalloying '75, ASM, 1977, pp. 2–8.
E. A. Almond, P. S. Mitchell, and R. S. Irani:Met. Tech., 1979, vol. 6, pp. 6, 205–14.
N.A. McPherson and T. N. Baker:Met. Sc, 1976, vol. 10, pp. 140–47.
R. Priestner:Rev. Metall., 1975, vol. 72, pp. 4, 285–96.
M.J. White and W. S. Owen:Metall. Trans. A, 1980, vol. 11A, pp. 597–604.
F.B. Pickering:Microalloying '75, ASM, 1977, pp. 9–30.
G. Bockstiegel and C. A. Blande.P/M Int., 1976, vol. 8, pp. 155–60.
T. J. Baker and J. A. Charles:The Effects of Second-phase Particles on the Mechanical Properties of Steels, ISI, 1971, pp. 79–87.
T. Malkiewics and S. Rudnik:JISI, 1963, vol. 201, pp. 33–38.
B. Dogan and T.J. Davies:P/M Int., 1983, vol. 15, I, pp. 11–16.
B. Dogan: Ph.D. Thesis, University of Manchester-UMIST, England, 1983.
R. Priestner and E. de los Rios:6th Int. Conf., ‘Heat Treatment ‘76’ Stratford-upon-Avon, 6–7 May 1976, pp. 129–34.
A.M. Sage:Met. Tech., June 1983, vol. 10, pp. 224–33.
B. Dogan and T. J. Davies:Metals Society 8th Int. Conf., ‘Heat Treatment ‘84’, London, 2–4 May, 1984.
W. Pesch, T. Schober, and H. Wenzl:Metall. Trans. A, 1980, vol. 11A, pp. 1821–25.
A. M. Sage:Conf. Proc., ‘Hot Working and Forming Processes’, July 1979, Sheffield, U.K., pp. 119–27.
Author information
Authors and Affiliations
Additional information
Formerly Postgraduate Researcher in the Department of Metallurgy and Materials Science, UMIST/University of Manchester, United Kingdom
Rights and permissions
About this article
Cite this article
Dogan, B., Davies, T.J. Thermomechanical processing of microalloyed powder forged steels and a cast vanadium steel. Metall Trans A 16, 1599–1608 (1985). https://doi.org/10.1007/BF02663015
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF02663015