Duplex Stainless Steel

Duplex Stainless Steel

Stainless steel belongs to the family of ferrous alloy metals. These components are made up of a chromium composition consisting of 10 to 30 percent of chromium. These low-carbon elements can be added with a few other alloys to give them enhanced performance and superior tolerances across various environments.

Duplex is part of the family of stainless steel. These austenitic-ferritic grades consist of two-phase metallurgical structures. It exhibits both austenite and ferrite in their make-up enabling, them to possess a duplex nature. The components of this steel vary across different grades. The most common elements include carbon, manganese, silicon, chromium, nickel, phosphorous, and sulfur. Molybdenum, nitrogen, and copper can also be added to further enhance the quality of the product.

The items from this grade have superior resistance against corrosion and erosion. These components exhibit good mechanical properties as well as high corrosion crack resistance. They can suffice in high pressure and temperature systems in different systems. Their superior toughness and ductility enable them to be utilized in various stress-induced environments. Since they are cheaper than standard austenitic grades, they are a preferred choice across various industries. The range of items within this range is widely used in construction projects, chemical processing, pollution control, naval parts, pulp, and paper production, brewing tanks, etc.

Is 304 stainless steel a duplex?

A 304 stainless steel is not a duplex metal. A 304ss is austenitic structure steel and doesn’t consist of a 2 phase microstructure. The items in the duplex range have a higher chromium concentration in comparison to the products in this range. Furthermore, they have superior resistance against corrosion and chloride pitting along with excellent strength. This allows them to be utilized across various industries.

Properties

The items from this range are designed with enhanced properties to help fight various natural and human-induced factors.

Physical properties

The modules are designed with a density of 7.805/cm3 along with a good thermal expansion of 13.7 x10^-6 /K. They have an excellent modulus of elasticity of 200 Gpa which, prevents them from deforming under stress. These modules can conduct heat up to 19 W/m.K helping it withstand extreme temperatures. Apart from this, the element has an electrical resistivity of 0.85 x10^-6 Ω .m. These sublime attributes enable them to be utilized across various systems.

Mechanical properties

The items within this grade have an excellent tensile strength of a minimum of 620 Mpa and have minimum proof stress of 450 MPa. They can be easily elongated by a minimum of 25% and still possess excellent workability. They exhibit a hardness of a maximum of 290 Brinell.

Does DSS rust?

These items are not impervious to rusting or corrosion. All modules rust if they are exposed to highly corrosive mediums. However, since this product range has a higher concentration of chromium, they have higher resistance to rust in the long run. To prevent further rusting, the steel can be processed further to give it enhanced protection.

Is it magnetic?

For any metal to be magnetic, it should have the presence of iron. In the dual structure range, the ferritic structure makes it magnetic in nature. They also have a crystal structure arranged in either martensitic or ferritic components which, is another requirement of a magnetic module. This is why the 2205SS grade is highly magnetic in nature.

What is lean Duplex?

In the early years of the metal industry austenitic, steel dominated the marketplace. These modules provided good corrosion resistance properties. When the requirement of strength aroused, martensitic items became a preferred choice. When both the elements were combined, both the properties were combined and utilized together. A lean duplex was a small offspring of this entire discovery. As time rolled on, the quality of the items slowly started increasing and, their chemistry was enriched.

A lean microstructure is a leaner and cheaper alternative to the major grade. This grade has slightly lower corrosion resistance and strength. But is widely used in various maintenance system applications.

Equivalent material

Grade UNS EN W-Nr SS DIN AFNOR
2707 S32707 - - - - -
2507 S32750 1.4410 - 2328 X 2 CrNiMoN 25 7 4 -
2205 (22Cr) S31803/ S32205 1.4462 1.4462 2377 X 2 CrNiMoN 22 5 3 Z 2 CND 22-05-03
2304 S32304 1.4362 1.4362 2327 X 2 CrNiN 23 4 Z 2 CN 23-04AZ