Superferritic stainless steel compositions containing 38%Cr and at least 2% each of Ni and Mo can be converted to sigma phase by heat treatment and then to powder by mechanical attrition. This powdered sigma phase has been experimentally processed by powder metallurgical techniques to produce green compacts which were consolidated in a hot isostatic press. Depending on composition, several of the powdered alloys were converted back to ferrite during hipping. The mechanism of the consolidation process, the nature of the microstructures produced, and the prognosis for its industrial exploitation are examined.
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References
1.
CORTIEM., WOLFFI., PREMACHANDRAK., TULLMINM., and MARSHE. DE: in Proc. Conf. ‘Stainless steels ‘91’, Chiba, Japan, June 1991, The Iron and Steel Institute of Japan,555–564.
BINDERW. and SPENDELOWH.: ASM Trans., 1951, 43, 759–777.
4.
TULLMINM. A. A.: ‘Development of experimental ferritic stainless steels containing 40% chromium’, PhD thesis, University of the Witwatersrand, Johannesburg, 1992.
5.
GILLI. R.: Platin. Met. Rev., 1990, 34, 85–97.
6.
HIGGINSONA., NEWMANR., and PROCTERR.: COITOS. Sei., 1989, 29, 1293–1318.
7.
CORTIEM. B., NANAS., and WOLFFI. M.: ‘Stainless steel material and the production of stainless steel artifacts therefrom’, South African Patent Application 95/2676, South African Patent Office, Pretoria, 1994.
8.
PREMACHANDRAK.: ‘Sigma phase formation in high chromium ferritic stainless steels’, MSc thesis, University of the Witwaters–rand, Johannesburg, 1993.
DEMOJ. J.: in ‘Handbook of stainless steel’, (ed. PecknerE. and BernsteinI. M.), Chap. 5; 1977, New York, McGraw Hill.
11.
WOLFFI. M., PREMACHANDRAK., and CORTIEM. B: Mater. Charact., 1992, 28, 139–148.
12.
WOLFFI. M. and BALLA.: Acta Metall. Mater., 1991, 11, 2771–2781.
13.
JACKSONE. M. L. E. M.: ‘Kinetics of sigma formation and dissolution in duplex stainless steels’, PhD thesis, University of the Witwatersrand, Johannesburg, 1997.
14.
CORTIENI. B. and PREMACHANDRAK.: Scr. Metall. Mater., 1992, 27, 1847–1852.
