Duplex stainless steel products for high strength, corrosion resistance, and enhanced resistance to stress corrosion cracking. They do not need to be painted or coated, meaning minimal maintenance. 2205 is the most widely used duplex (ferritic/austenitic) stainless steel grade. It finds applications due to both excellent corrosion resistance and high strength. The standard duplex S31803 composition has over the years been refined by many steel suppliers, and the resulting restricted composition range was endorsed as UNS S32205 in 1996. Duplex S32205 gives better guaranteed corrosion resistance, but for much of the Duplex S31803 currently produced also complies with Duplex S32205. 2205 is not generally suitable for use at temperatures above 300ºC as it suffers from precipitation of brittle micro constituents, nor below -50ºC because of its ductile-to-brittle-transition. Unlike carbon steels, Forta range duplex products, with their superior corrosion resistance, do not need to be painted or coated, making them a more cost effective long-term choice. Because duplex products are also high strength, thinner gauges can potentially be used, which saves on material costs. Duplex also has a similar thermal expansion to carbon steels making it possible to combine the two in the same application. In terms of a common engineering material, modern duplex stainless steels emerged in the early 1980s, developed from cast alloys. Their popularity stems from an attractive combination of properties, including high strength and excellent resistance to chloride stress corrosion cracking. The present paper gives a brief review of the history and some recent developments of duplex stainless steel grades and the improvements made on the standard S32205 DSS lowering the Ni and Mo contents to produce an economical alternative of the well-known grade or in the case of the superduplex S32750 grade increasing the content of Cr, Mo and Nor elevating the content of Cr, N, Cu and W in combination with relatively lower contents of Ni and Mo to improve the strength, toughness and corrosion properties for the oil industry. Parallel to the development of higher-alloy duplex grades for corrosive conditions, there has recently been a great interest in leaner compositions for wider purposes with lower amounts of expensive alloying elements. In this respect, a new patent correspond to the type S32101 DSS has been developed. Finally, the most modern applications in the field of oil and petrochemical industry are described and the major uses of the three main grades, lean, 2205 and 2507, are commented.
Duplex steel also supplied according to following standard and specifications.
ASTM A182 STEEL FLANGES, ASTM A240 STEEL PLATE, ASTM A276 STEEL BAR, ASTM A789 STEEL TUBE, ASTM A790 STEEL PIPE, ASTM A815 STEEL, UNS S31803 STEEL PLATE, UNS S32205 STEEL PLATE, AFNOR Z3CrNi22.05AZ, SS 2377 STEEL PLATE.
- High resistance to chloride stress corrosion cracking
- Resistance to chloride pitting and crevice corrosion
- Good general corrosion resistance
- Good sulfide stress corrosion resistance
- High Strength
- Good weldability and workability
- Pressure piping systems for seawater, chemicals, and oil and gas handling and heat exchangers
- Pressure vessels like digesters, evaporators, fermenters, autoclaves, water heaters, bleach washers, chip pre-steaming vessels and road tankers
- Storage tanks for pulp, chemicals, biofuels, beverages, grains, and ore slurry
- Chemical processing, transport and storage.
- Marine and other high chloride environments
- Paper digesters and paper machines
- Food processing equipment