Community Research and Development Information Service - CORDIS


Final report on Contract No 7210-PR/167, 01/07/1999 to 30/09/2000.

Refinement of grain size is the standard way to improve both strength and toughness, and recent work has indicated that ultra-fine (UF) grain structures of around 1 µm could be achieved in commercial production. This project assessed the benefits that are likely to be achievable in low carbon/µA and stainless steel flat products from ultra-fine polygonal grain sizes (-1 µm), and how these might be produced for bulk manufacture. Significant progress has been made in the areas of UF dual phase strip, UF surfaces to plate by alternative process routes, and UF stainless steel from reversion of deformation-induced martensite after cryogenic rolling of a metastable austenitic composition.

A homogeneous grain structure of around 1.2 µm was achieved in a metastable austenitic stainless steel by heavy deformation at -70 °C followed by three-hour annealing at 750 °C. Further work would be required to optimise the processing for a finer grain size and for a full assessment of the resultant properties.

Generally, the ferritic UF structure is very strong but with extensive Lüdering and little work hardening, thus severely restricting the potential applications of such steels. UF dual phase (ferrite/martensite) steel shows superior properties. Fine grains, 2-3 µm, should offer a more attractive processing-cost/product-property balance. Alternatively, higher carbon UF steels should be worthy of further study, with substantial quantities of carbide introducing useful work hardening through the dual phase effect. This should be worth examining in rod/wire and engineering steel applications, besides flat products.

Additional information

Authors: VANDENBERGHE L, CRM, Zwijnaarde (BE);BARTERI M, CSM, Terni (IT);MECOZZI M, CSM, Terni (IT);HERZIG C, IEHK-RWTH, Aachen (DE);HOWE A, Corus UK Ltd, Rotherham (GB);NEWNHAM S J, Corus UK Ltd, Rotherham (GB)
Bibliographic Reference: EUR 20225 EN (2002), pp.137. Euro: 20.50
Availability: EUR-OP reference: KI-NA-20225-EN-S Available from EUR-OP sales agents. URL:
ISBN: ISBN: 92-894-3249-7
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