Duplex stainless steel wire mesh types, uses, characteristics

Duplex stainless steel wire mesh types, uses, characteristics

Duplex stainless steel wire mesh is a special alloy, acid and alkali resistant and corrosion resistant, mainly used in the chemical industry. Duplex stainless steel has good welding performance. Compared with ferritic stainless steel and austenitic stainless steel, it is neither like the welding heat affected zone of ferritic stainless steel, which has a significant reduction in plastic toughness due to severe grain coarsening, nor is it like austenitic stainless steel, which is sensitive to welding hot cracks.

Due to its special advantages, duplex stainless steel is widely used in industrial fields such as petrochemical equipment, seawater and wastewater treatment equipment, oil and gas pipelines, papermaking machinery, etc. In recent years, it has also been studied for use in the field of bridge load-bearing structures and has a good development prospect.

According to its chemical composition, duplex stainless steel can be divided into four types: Cr18, Cr23 (without Mo), Cr22 and Cr25. Cr25 duplex stainless steel can be divided into ordinary type and super duplex stainless steel, among which Cr22 and Cr25 are more widely used. Most of the duplex stainless steel used in my country is produced in Sweden, with specific grades: 3RE60 (Cr18), SAF2304 (Cr23), SAF2205 (Cr22), SAF2507 (Cr25).

The first category is low alloy type, represented by the grade UNS S32304 (23Cr-4Ni-0.1N). The steel does not contain molybdenum, and the PREN value is 24-25. It can replace AISI304 or 316 in terms of stress corrosion resistance.

The second category belongs to the medium alloy type, the representative grade is UNS S31803 (22Cr-5Ni-3Mo-0.15N), the PREN value is 32-33, and its corrosion resistance is between AISI 316L and 6%Mo+N austenitic stainless steel.

The third category is high alloy type, generally containing 25% Cr, molybdenum and nitrogen, and some also contain copper and tungsten. The standard grade is UNSS32550 (25Cr-6Ni-3Mo-2Cu-0.2N), and the PREN value is 38-39. The corrosion resistance of this type of steel is higher than that of duplex stainless steel with 22% Cr.

The fourth category is super duplex stainless steel, containing high molybdenum and nitrogen, standard grade UNS S32750 (25Cr-7Ni-3.7Mo-0.3N), some also contain tungsten and copper, PREN value is greater than 40, can be used in harsh media conditions, has good corrosion resistance and mechanical comprehensive properties, comparable to super austenitic stainless steel.

Duplex stainless steel wire mesh, commonly 2205 duplex stainless steel wire mesh, 2507 duplex stainless steel wire mesh, is woven with duplex stainless steel wire, mainly used for filtration under corrosive conditions such as seawater and nuclear industry.

Introduction to duplex stainless steel: With the development of industrial technology, it is difficult for general austenitic stainless steel to meet the requirements of stress corrosion, pitting corrosion and crevice tunnel corrosion. For this reason, metallurgical industry has conducted a lot of research and developed austenitic-ferritic stainless steel, namely duplex stainless steel.

The biggest advantages of duplex stainless steel:

①Excellent stress corrosion resistance (SCC), high acid corrosion resistance (acetic acid, formic acid, etc.); ②Sufficient resistance to pitting and crevice tunneling corrosion; ③1 times higher than the yield strength (仉) of austenitic stainless steel, and good plasticity and toughness; ④Lower linear expansion coefficient than austenitic stainless steel, close to low carbon steel. Disadvantages of duplex stainless steel: ①Compared with austenitic stainless steel, the heat resistance is lower, controlled below 250℃; ②Forging and cold stamping formability is high, not as good as austenitic stainless steel; ⑧There is a medium temperature brittle zone (female ilcr phase, 475 brittleness), which is not conducive to heat treatment and welding.