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SUPER DUPLEX

As part of its long tradition of manufacture, one of the areas in which ELG Carrs Stainless Steels concentrates its activities is in the production of Duplex and Super Duplex steel with ISO 9001, NORSOK M650 and TÜV accreditation.

The company has gained a worldwide reputation supplying guaranteed quality to customers who demand the highest levels of quality such as Exxon Mobile (Mobil) and the U.K. Ministry of Defence.

Deriving their name from the duplex microstructure of both ferrite and austenite, and featuring properties of both classes, Duplex steels are based on high Chromium, high Nickel steels from 20% Chromium and 5% Nickel. They are used where superior properties are needed compared to 316 austenitic for strength, corrosion resistance in chloride media, ductility and resistance to stress corrosion cracking. Although a compromise between the two ‘pure´ types, duplex grades can offer some unique property solutions and have the following characteristics:

• higher corrosion resistance
• higher strength properties than the austenitic steels
• they cannot be hardened by heat treatment
• improved toughness and ductility (compared to ferritic grades)
• superior chloride corrosion resistance and pitting resistance
• high yield strength offers designers the use of thin-wall material (which can lead to major reductions in weight) with adequate pressure-containing and load-bearing capacity
• resistant to stress corrosion cracking but not to the same level as ferritic grades
• Duplex grades are readily welded
• they have high tensile strengths

Commonly used in aqueous, chloride-containing environments and as replacements for austenitic stainless steels that have suffered from either chloride SCC or pitting during service, common uses include:

• Heat exchangers
• Marine applications
• Desalination plants
• Food pickling plants
• Off-shore oil & gas installations
• Chemical & petrochemical plant

ELG Carrs Stainless Steels supply fully tested material to NORSOK M650, which includes chemical, mechanical, ferrite as per E562, G48 corrosion tests, micrographic examination and impact tests as standard on mill certs.