Among the discussions on fasteners and SS industries, especially in India, two words are quite frequently mentioned: Duplex fasteners and SS bright bars. Both belong to the broad category of stainless steel products but are somewhat different from one another in composition, production process, application, and properties. So, here, we will discuss the difference between Duplex fasteners and SS bright bars along with a discussion on international standards, grades, types, and their use.

What Are Duplex Fasteners?
Duplex fasteners are a class of fasteners made of duplex stainless steel. Duplex stainless steel is a mix of both austenitic and ferritic stainless steels, and this mixture confers to it properties unique from both. These duplex fasteners are normally applied in high-strength and high-corrosion and reliability conditions, which involve industries such as chemical processing, oil and gas, marine environments, and power generation.

Types of Duplex Stainless Steel
There are many grades of duplex stainless steels. The commonly applied grades in fasteners are as listed below.

2205 (UNS S31803) :This is one of the duplex grades that widely used and has high tensile strength properties with excellent corrosion resistances specially in chloride.

2507 (UNS S32750): This super duplex steel possesses greater strength and is superior than 2205 with pitting and crevice corrosion.

Both these grades comply with international standards such as ASTM A193 and ASTM A320 that give requirements for stainless steel fasteners, which includes mechanical properties and corrosion resistance.
 
What Are SS Bright Bars?
Cold-finished steel bars, with a glossy and shiny surface finish, smooth and polished through processes that may be cold drawing and centerless grinding, or similar other surface finish giving operations. They are available in the following stainless-steel grades: 304, 316, or 410. SS bright bars are used for making shafts, bolts, pins, etc., as structural components where extremely high-quality and precision requirements exist in terms of surface finish, size, and straightness before final machining and fabrication work.

Grades of SS Bright Bars

Some of the more common grades of SS bright bars include:

304 (UNS S30400): Austenitic stainless steel that offers the advantage of corrosion resistance with a versatility that finds a lot of applications in the food processing, pharmaceutical industries, and architectural application. 

316 (UNS S31600): Another austenitic grade that has got better corrosion resistance especially towards marine and chemical environments.

410 (UNS S41000): A martensitic stainless steel with moderate corrosion resistance and used extensively in applications requiring high strength and hardness.

These SS bright bar manufacturers in India are in accordance with international standards like ASTM A276 and A484, which provide guidelines for chemical composition, mechanical properties, and dimensional tolerances.

Composition and Structure:

Duplex fasteners include the austenitic-ferritic phases in duplex stainless steel, which will have a good mechanical property.
Bright SS bars come in numerous grades of stainless steel grades are mostly austenitic and are suitable for good precision machinability.

Use of duplex fasteners:

The use of duplex fasteners can be applied in seriously corrosive environment, like the ones experiencing offshore services, or the chemical plants.
SS bright bars are used for the manufacture of such parts like shafts, pins, and bolts where surface finish and accurate dimensions matter.

Strength and Durability:

Duplex fasteners manufacturers in India offer higher strength and corrosion resistance especially in chloride-rich environments and SS bright bars, by grade, have different levels of corrosion resistance but the focus is more on easy machining and surface quality.

International Standards:

Both duplex fasteners and SS bright bars are according to international standards. Duplex fasteners are usually manufactured according to a standard such as ASTM A193 whereas SS bright bars are according to a standard such as ASTM A276.

Types:
Duplex fasteners include bolts, nuts, washers, and screws made of duplex stainless steel.
SS bright bars are available in various shapes, including round bars, square bars, and hexagonal bars.

Conclusion

Duplex fasteners and SS bright bars are the necessities in all industries with some distinct specialties. The main feature of duplex fasteners is its strong strength, resistance to corrosion, and use in hostile environments, whereas the uniqueness of SS bright bars is achieved through its high precision and good finish, besides it has various benefits in machining. Hence the differences in the composition standards, and use can determine the appropriate materials needed.

There are many manufacturers in India that produce such quality stainless steel products so that the international standard is met and cater to local as well as international demand. Whether it is duplex fasteners or SS bright bars, selection of suppliers who can provide quality material, standards adherence, and customer service is crucial.