Steel duplex

Duplex stainless steels (ca 4% nickel, 23% chrome) have been identified as having potential appHcation to nitric acid service (75). Because they have a lower nickel and higher chromium content than typical austenitic steels, they provide the ductabdity of austenitic SS and the stress—corrosion cracking resistance of ferritic SS. The higher strength and corrosion resistance of duplex steel offer potential cost advantages as a material of constmction for absorption columns (see CORROSION AND CORROSION CONTROL). 

Table 3.14 Typical analyses of some duplex steels...

In duplex steels, ferrite is a major intentional constituent. The features noted above are relevant the two phases do have differing analyses but not to such an extent as to cause serious corrosion problems. A further... 

While not immune to cracking, the duplex steels are also much more resistant than are the austenitics and are increasingly being used for this reason. Their characteristics have been reviewed elsewhere . 

Duplex, and super-duplex stainless steels, contain high percentages of chromium. They are called duplex because their structure is a mixture of the austenitic and ferritic phases. They have a better corrosion resistance than the austenitic stainless steels and are less susceptible to stress corrosion cracking. The chromium content of duplex stainless steels is around 20 per cent, and around 25 per cent in the super-duplex grades. The super-duplex steels where developed for use in aggressive off-shore environments. 

The corrosion resistance of duplex steels is comparable in corrosion resistance with austenitic steels as ... 

Table 4.13 PRE values for some duplex steel grades...

Duplex steel can be used in unpressurized storage tanks of all kinds. The storage tanks are used for phosphoric acid. A storage tank of dimensions 13 m diameter, 12 m height, 1590 m3 volume fabricated from 316 L stainless steel weighs 33 900 kg compared with... 

The mechanical and physical properties of some alloys chosen for rebar in concrete are relevant in the performance of the alloys. The mechanical properties of some reinforcing bar alloys are given in Table 7.11. All the steels except duplex steels were subjected to cold work in order to increase their strength. Duplex S31803 steel in the annealed state exhibits strength levels close to the values of the cold-worked alloys. 

The most commonly used metals in drilling and well stimulation11-13 are low-alloy carbon steel (API Grades J-55, L-80, N-80 coiled tubing) quality tubing (grades QT-70, 80, 1000) chrome alloy steels (ASM Grade Cr-13, duplex steel). 

The guideline for high-alloy tubular materials is set at 0.05 lb/ft2 chrome and duplex steels are used to fight bottom hole corrosion. 

Materials such as metals, alloys, steels and plastics form the theme of the fourth chapter. The behavior and use of cast irons, low alloy carbon steels and their application in atmospheric corrosion, fresh waters, seawater and soils are presented. This is followed by a discussion of stainless steels, martensitic steels and duplex steels and their behavior in various media. Aluminum and its alloys and their corrosion behavior in acids, fresh water, seawater, outdoor atmospheres and soils, copper and its alloys and their corrosion resistance in various media, nickel and its alloys and their corrosion behavior in various industrial environments, titanium and its alloys and their performance in various chemical environments, cobalt alloys and their applications, corrosion behavior of lead and its alloys, magnesium and its alloys together with their corrosion behavior, zinc and its alloys, along with their corrosion behavior, zirconium, its alloys and their corrosion behavior, tin and tin plate with their applications in atmospheric corrosion are discussed. The final part of the chapter concerns refractories and ceramics and polymeric materials and their application in various corrosive media. 

Austenitic-ferritic Chromium-Nickel Steel X5CrNiMoCu255 (W.No. 1.4596) The duplex steel obtains the corrosion resistance from Cr, Ni and Mo. The strength... 

The material is a nitrogen alloyed duplex steel. The development has been continued to higher alloyed types (f.e. 1.4467 X3CrMnNiMoN2564)... 

Lake, T., 1990, Duplex steels resist corrosion in heat transfer. Proc. Ind. J. July 15 -17. 

Schmitt [52] reviewed the effect of elemental sulfur on corrosion of construction materials (carbon steels, ferric steels, austenitic steels, ferritic-austenitic steels (duplex steels), nickel and cobalt-based alloys and titanium. Wet elemental sulfur in contact with iron is aggressive and can result in the formation of iron sulfides or in stress corrosion cracking. Iron sulfides containing elemental sulfur initiate corrosion only when the elemental sulfur is in direct contact with the sulfide-covered metal. Iron sulfides are highly electron conductive and serve to transport electrons from the metal to the elemental sulfur. The coexistence of hydrogen sulfide and elemental sulfur in aqueous systems, that is, sour gases and oils, causes crevice corrosion rates of... 

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