4. Austenitic-ferritic stainless steels
4.1 Chemical composition, structure and general properties
Austenitic-ferritic stainless steels, known as "duplex" steels, contain 20-30% chromium, 2-10% nickel and between 0.1 and 0.3% nitrogen (table 7 ). They may also contain other elements such as molybdenum (up to approx. 4.5%), copper (up to 2%) and tungsten.
Modern duplex steels have two main characteristics:
a two-phase structure (45% ferrite, 55% austenite) obtained by balancing alphagenic (Cr, Mo, Si...) and gammagenic (Ni, N, Cu, C) elements and a judicious choice of heat treatment temperature. This structure is in the hyper-quenched state, free from precipitation of brittle phases (σ, χ...)...
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Austenitic-ferritic stainless steels
Austenitic steels
Bibliography
Basic works
Reference
In Engineering Techniques
On stainless steels
On forming
About welding
Basic works
Standardization
Series of AWS standards (published by AWS).
ASTM series of standards (distributed by ASTM International).
Series of NF EN standards (distributed by AFNOR).
- Standard Test Method for Determining Volume Fraction by Systematic Manual Point Count - ASTM E 562 - 2002
- Standard Practice for Detecting Susceptibility to Intergranular Attack in Austenitic...
Regulations
Directive 97/23/EC of the European Parliament and of the Council of May 29, 1997 on the approximation of the laws of the Member States concerning pressure equipment, known as the Pressure Equipment Directive (PED), OJ L181 of July 9, 1997.
Organizations
UNS numbers (unified numbering system for metals and alloys)
http://www.matweb.com/search/SearchUNS.asp
Center technique des industries mécaniques (Cetim)
Syndicat national de la chaudronnerie,...
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