Select Page

Due to their unique combination of strength, corrosion resistance, and cost-effectiveness, super duplex stainless steels are well-suited to be used in industrial fasteners, because they are able to combine strength, corrosion resistance, and cost-effectiveness.

Stainless steels made from duplex materials combine the greatest advantages of austenitic stainless steels and ferritic stainless steels, namely its good strength and toughness, relative easy fabrication, and high resistance to corrosion and stress corrosion cracking when in contact with water.

Is The Super Duplex Different From Duplex 

On the basis of the microstructural phases that exist in stainless steels, different classes are derived. Although each class has their own microstructure phase, stainless steels in the duplex category have a microstructure that is similar to those of iron and austenitic stainless steels, as well as ferritic and austenitic stainless steels. Duplex stainless steel is stainless steel with a microstructure of austenite and ferrite combined. Due to the fact that both of these crystalline stainless steel structures have an equivalent ratio, it results in duplex stainless steel having a 50/50 mix of austenite and ferrite. There are three other categories of duplex stainless steel, one of which is super duplex stainless steel.

Super Duplex Stainless Steels Fasteners

The super duplex grades are also characterized by their dual microstructures. This gives the PREN values of duplex steel grades to be extremely high. These numbers can range from 22 to 45. There is a significant difference in corrosion resistance between the super duplex kind of stainless steel and the other two kinds of duplex stainless steel. The PREN values for super duplex grades are between 38 and 45, so they are the best grade of stainless steel available. This high alloyed chemistry of stainless steel grades A - 5 is a lot more extensive than that of any other is stainless steel an alloy that we have to offer. Because the stainless steel alloys are extensively alloyed, the stainless steel grades are more resistant to corrosion than grades 304 or 316.

Despite the fact that this stainless steel is an alloy of offers high strength and corrosion resistance, its highly alloyed nature makes them difficult to process as well as having great mechanical strength. Further, the creation of intermetallic phases is easier when higher levels of elements like chromium, nickel, molybdenum, nitrogen, and even tungsten are present. It is due to these intermetallic phases that the super duplex stainless steel variant has a greatly reduced impact resistance once it has been processed. As a result, customers should work with manufacturers or suppliers who are knowledgeable as well as capable of delivering quality products. The final product will be poor if either stainless steel grade is incorrectly made.

The Properties Of Super Duplex Stainless Steel

Stainless steel that is duplex can typically be twice as strong as standard austenitic stainless steel such as Alloy 316L in the 3xx series. The minimum yield strength of a 2205 duplex stainless steel is 65 kilos (450 MPa), whereas that of an alloy like 316L (UNS S31603, 1.4404), it is only 25 kilos (170 MPa).

Compared to the conventional grades of steel, UNS S32750 (F53, 1.4410) and UNS S32760 (F55, 1.4501) have a yield strength of 80ksi (550MPa) even higher than those grades alone. As far as super duplex stainless steels are concerned, this particular super duplex stainless steel is one of the strongest of all super duplex stainless steels, with a minimum yield strength of 85ksi (586MPa).

Super Duplex Stainless Steels Fasteners

Further processing can improve the strength of these alloys, in addition to the obvious advantages previously mentioned. In the case of duplex stainless steels, it is possible to work-harden them so that the yield stress and ultimate tensile strength can be increased, however, the elongation value may also drop.

If a standard stainless steel, such as UNS S32750 (F53, 1.4410), is reduced by approximately 25% in its area, it can double its strength. In order to accomplish this, cold working can be performed, such as drawing or cold forging, but only with smaller diameter bars. A small amount of cold working can also be applied during the machining process, if the component is operated in tension with minimal shock loading. Combined, these two qualities will result in high strength but reduced toughness.

Second, aging critical components can also lead to significant improvements in their performance. Ferralium 255-3AF is a solution-annealed version of the product that is aging. It is possible to increase the yield strength marginally if the forged bar or machined component is subjected to additional heat treatment, while at the same time increasing the tensile strength by at least 5-10%.

The Evolution Of Super Duplex Steel Fasteners:

Modern fasteners have been made of super duplex steel since the 1970s due to their high degree of similarity and survival in applications. The 32750 Super Duplex Steel Fasteners feature chromium and nickel alloys that are much stronger and more tensile than stainless steel. With the development of super duplex steel fasteners, three major issues associated with stainless steel screws were addressed: corrosion resistance, fatigue resistance, and high-temperature strength.

First, the chrome and nickel contents in the alloying components were boosted to prevent oxidation and, thus, prevent rust formation.

Super Duplex Stainless Steels Fasteners

By adding nickel to the design, a second issue has been resolved by increasing toughness and flexibility as well as enhancing wear resistance. Besides molybdenum, another component was added, allowing super duplex steel fasteners to resist temperatures of up to 1200 degrees Celsius without melting.

Stainless steel cheats time is not as effective as super duplex preparations when it comes to erosion obstruction because they are diacetyl-safe and can withstand high temperatures without losing firmness, unlike other composites that lose firmness under high temperatures.

Duplex Super Duplex Steel Fasteners S32750 and S32760

There is no doubt that Mehtametals Super Duplex steel Fasteners are a popular product with a very broad range of applications. In order to serve our clients, we make sure that we provide the best possible service while maintaining the highest quality. Additionally, we have developed a highly efficient and cost-effective product that can compete in both domestic and foreign markets. In the case where corrosion resistance and strength are of extreme importance, these stainless steel types and uses steel fasteners are usually used. Nitrogen, molybdenum, and chromium are the three components of the pieces, and they offer excellent resistance to crevice corrosion and chloride pitting, due to their chemical composition. 

This S32750 / S32760 Super Duplex Steel Fastener has an extremely unique metallurgical microstructure because it is a 50-50 mix of ferrite and austenite steels. In addition, the advantages of employing these fasteners include their excellent mechanical and physical steel properties such as their high yield strength, their outstanding tensile strength, their high impact resistance, as well as their excellent corrosion resistance. 

There is no doubt that Super Duplex Steel Fasteners are able to satisfy the high requirements imposed by the petroleum, petroleum, and maritime industries because they have superior physical and mechanical characteristics. Molybdenum and chromium are an ideal ratio in it, which makes it exceptionally corrosion resistant. 

The fasteners we produce are made of a variety of metals and qualities that are needed in each application, and we use only the best metals and qualities for the job. This alloy is made up of chromium, nickel, and molybdenum. These metals are all resistant to corrosion in crevices, oxidation, and chloride pitting. This alloy can be used in a wide variety of acidic environments. The high-grade Super Duplex Steel Fasteners we provide are characterized by their outstanding hardness of the steel uses excellent tensile strength, and resistance to pitting and crevices as well as their high workability and durability. 

Applications Of Super Duplex Stainless Steel Fasteners

Stainless steels such as Super Duplex combine the strength of ferritic and austenitic steel types. They offer better corrosion resistance than ferritic steels. The super duplex stainless steel is used for a wide range of applications, including oil and gas pipelines, heat exchangers used in the sea, equipment used to handle seawater, desalination equipment, scrubber systems for power plants, vessels containing aggressive media, and tanks containing liquefied natural gas.

The microstructure of duplex stainless steel is a mix of austenite and ferrite. It provides duplex stainless steel with high strength and corrosion resistance, while at the same time providing similar corrosion resistance as austenitic stainless steel. The yield strength of Alloy 2205 duplex stainless steel (UNS S32205, 1.4462) is 65ksi (450MPa), while the yield strength of Alloy 316L is just 25ksi (170MPa).

In addition to being corrosion-resistant, duplex stainless steel fasteners are relatively easy to manufacture, and combine the strengths of austenitic stainless steel benefits and ferritic steel in one package. Among them are cracking resistance, strength, and toughness.

Advantages Of Super Duplex Stainless Steel Fasteners

Aside from the advantages stated above, they also have the ability to strengthen themselves further by adding additional processing such as hardening. For example, stainless steel fasteners made of Duplex stainless steel can be hardened, which elevates yield stress and ultimate tensile strength and reduces the elastic properties of steel.

A Super Duplex Steel S32750 Fastener such as UNS S32750 offers high strength as well as extraordinary corrosion resistance. It is particularly effective in chloride-bearing environments such as brackish water, seawater, and freshwater.

Occasionally, cold forming can double the strength of steel, but can only be used for small-diameter bars. However, it is only applicable to smaller bars. This steel has low toughness under impact loads. However, if the component will work under tension and with limited impact loading, this is an acceptable characteristic.

Super Duplex Steel Fasteners Features:

  • It is also essential to highlight the fact that Super Duplex steel is also a miniature completing compound, which further enhances the corrosion resistance of the steel, as well as resisting corrosive environments, whether freshwater or salt water.
  • Among all weldable materials, SUPER DUTTON holds a position of the highest return strength, pliability, and formability.
  • It is rated as having corrosion resistance of a third of that of stainless steel; for this reason, it is considered to be the most corrosion-resistant steel on the market today.
  • There is no pitting of this material even at temperatures as high as 425°C (825°F).