Community Research and Development Information Service - CORDIS

Abstract

Final report on Contract No 7210-MA/133, 134, 323, 324, 1 July 1996 to 30 June 1999.

The nitrogen content of duplex stainless steels has to be chosen very carefully to achieve desirable results with respect to processing, corrosion and mechanical properties. In this project, variations of materials from experimental heats with different nitrogen contents up to 0.40% and adjusted chemical composition - partly by thermodynamical analysis - have been investigated in the solution annealed and hot and cold rolled conditions. The mechanical and corrosion resistance of high nitrogen alloyed duplex stainless steels have been measured and discussed and the results obtained show that nitrogen became rather unavoidable in the design of improved stainless duplex grades.

A main advantage of duplex microstructure in comparison with single phase ones results in a dramatic change in the evolution during forming, recovery and recrystallisation. The processes of nucleation and growth involved in phases and microstructure changes are impacted by alpha - gamma interfaces and therefore cannot be extrapolated from phenomena involved in single phased ferritic or austenitic steels. Low cycle fatigue behaviour, corrosion fatigue and stress corrosion properties show that duplex design can in some cases take advantage of the weaker phase to reinforce the stronger one and vice versa. Structural stability tests show that there is a clear positive effect of nitrogen on retarding phase precipitation but even a high nitrogen level is not effective in reducing the rate of phase precipitation when sensitising a material with very high Mo content (>4 %).

Additional information

Authors: HOCHORTLER G, Bohler Edelstahl GmbH, Kapfenberg (AT);KEICHEL J, IMM/RWTH, Aachen (DE);GOTTSTEIN G, IMM/RWTH, Aachen (DE);COUDREUSE L, Creusot-Loire Industrie, Le Creusot (FR);MASSOL K, USTL/LMP, Villeneuve D'Ascq (FR);VOGT J B, USTL/LMP, Villeneuve D'Ascq (FR);FOCT J, USTL/LMP, Villeneuve D'Ascq (FR);HOCHÖRTLER G, Böhler Edelstahl GmbH, Kapfenberg (AT)
Bibliographic Reference: EUR 20326 EN (2002), pp.131. Euro: 20.50
Availability: EUR-OP reference: KI-NA-20326-EN-S Available from EUR-OP sales agents. URL: http://eur-op.eu
ISBN: ISBN: 92-894-3665-4
Record Number: 200214925 / Last updated on: 2002-07-12
Category: PUBLICATION
Original language: en
Available languages: en