Segregation of manganese during intercritical annealing of dual phase steels
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and hot rolled to 25 mm thick slabs. Blanks (25 m m •
1. J. M. Gray: Processing and Properties of Low Carbon Steel, J. M. Gray, ed., AIME, New York, NY, 1973, pp. 225-42. 2. K. J. Irvine, T. Gladman, J. Orr, and F. B. Picketing: J. Iron Steel Inst., 1970, vol. 208, pp. 717-26. 3. H. Nordberg and B. Aronsson: J. Iron Steel Inst., 1968, vol. 206, pp. 1263-66. 4. J. G. Williams, I. D. Simpson, and J. K. McDonald: Australian Iron & Steel Pry. Ltd., unpublished research, 1981. 5. C. A. Nolasco, E. Q. Oliveira, and P. J. P. Bordignon: Metalurgia ABM, 1977, vol. 33, pp. 257-63 (in Portuguese). 6. R. Coladas, J. Masounave, and J.-P. Bailon: The Hot Deformation of Austenite, J. B. Ballance, ed., AIME, New York, NY, 1977, pp. 341-7Z 7. D.R. Barraclough: Metallography, 1973, vol. 6, pp. 465-72. 8. J.M. Hyzak and I.M. Bemstein: Metall. Trans. A, 1976, voI. 7A, pp. 1217-24.
100 mm x 275 mm) were machined from these slabs, reheated at 1200 ~ for 45 minutes, hot rolled to 3 mm thick plate, and immediately stored in a salt bath at 600 ~ for one hour (to simulate coiling in a batch annealing production line), then cooled in air. Small blanks were sheared from these plates and given the following intercritical annealing treatments:
Segregation of Manganese during Intercritical Annealing of Dual Phase Steels N. PUSSEGODA, W. R. TYSON, P. WYCLIFFE, and G. R. PURDY As part of a study of the production of dual-phase steels by batch annealing, substitutional solute element partitioning of manganese during intercritical annealing was investigated. Such information is necessary to understand changes in volume fraction and hardenability of the austenitic phase and the mechanical properties of its transformation products produced during cooling. In the batch annealing process, cooling is slow and high hardenability is required of the austenitic phase in order to obtain high-strength transformation products. Hence, high levels of alloy additions are required. Mn is the most economical alloying element which can provide this hardenability. The kinetics of transformations during intercritical annealing have been studied both theoretically and experimentally by Wycliffe, Purdy, and Embury, 2'~ and experimentally by Speich, Demarest, and Miller. 3 Wycliffe et al. developed a detailed model based on local equilibrium, which enabled alloy element redistribution during annealing to be predicted. Evidence for Mn segregation was obtained in both above-mentioned studies. The purpose of the present communication is to provide further data on this phenomenon. The chemical composition of the steel used was (in wt pct) 0.06 C, 2.83 Mn, 0.33 Si, 0.01 P, 0.01 S, and 0.03 A1. The steel was prepared as Al-killed induction melted 136 kg heats, and cast into rectangular ingots of 68 kg each. The ingots were split in half and soaked at 1200 ~ for two hours N. PUSSEGODA, formerly Postdoctoral Fellow at PMRL, CANMET, is now with the Department of Mechanical Engineering, University of Peradeniya, Sri Lanka. W.R. TYSON is Head of Engineering and Metal Physics Sect
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