Stainless steels have become a more common choice because of their excellent corrosion resistance. Its by-products are formed by changing the composition of the different alloying elements. Austenitic, martensitic, ferritic, duplex and precipitation-hardened stainless steels are the main types of stainless steels. There are different grades of duplex stainless steels like F51, F53, F55, F61 etc. Grade F51 in Birmingham is generally a 22% Cr duplex stainless steel. Take a dig into some interesting facts surrounding duplex stainless steel.
Facts About Duplex Stainless Steels
Duplex stainless steels have a two-phase microstructure of austenitic and ferritic steels. Its mechanical properties are based on the relative amounts of austenite and ferrite forming elements available in the composition.
Classification of Duplex Stainless Steel
Duplex stainless steel is classified majorly into four types:
- Lean Duplex
- Super Duplex
- Hyper Duplex
Properties of Duplex Stainless Steel
1. Mechanical strength
This category of steel has higher mechanical strength as compared to other grades like ferritic and austenitic. It enables using thinner sections and aids in reducing weight. Machining of duplex stainless steel is tough as well as slower than austenite because of its greater mechanical strength.
2. Corrosion resistance
The corrosion resistance properties of duplex stainless steel are equivalent or even higher as compared to austenitic. This is because of its higher chromium content combined with Molybdenum, which makes it more resistant to pitting and crevice erosion. Grades are ranked depending on their resistance to pitting using Pitting Resistance Equivalent Number (PREN).
3. Stress Corrosion Cracking Resistance
Austenitic grades are more prone to SCC, whereas ferritic grades have higher resistance to it. Coming to duplex stainless steels it has higher SCC resistance than austenitic but lower when compared to ferritic grades. SCC initiates to an austenitic area in duplex stainless steel but is arrested at the ferritic crystal structure available at the boundary. This prevents the propagation of cracks and raises uptime.
Welding is more difficult than austenitic. Heat input and cooling rate must be controlled closely to prevent the buildup of unwanted intermetallic phases.
Benefits of Duplex Stainless Steel
- It has higher strength that allows the use of thinner gauges, which is useful where lighter fabrications are required.
- Prices of stainless steel depend mainly upon one specific commodity: Nickel. This category of steel consists of low Nickel content, eventually making it immune to the price fluctuations of commodity prices.
These two are the key advantages of duplex stainless steel, which makes it cheaper with superior properties for certain applications.
Duplex Stainless Steel Applications and Uses
- Oil and gas exploration and processing tools- heat exchangers, tubing and piping
- Processing, transport and storage of chemicals- piping, pressure vessels, heat exchangers and tanks
- Pulp and paper industry- stock-handling systems, bleaching equipment and digesters
- Marine and other high-chloride environments
- Food processing equipment
- Cargo tanks for trucks and ships
- Biofuels plants
Lolu Alloys Ltd is the leading supplier of Grade F51 steel in Birmingham and nearby areas. Contact us today or check our website for more information about our products.