Duplex stainless steel is a very corrosion resistant and hardenable alloy. Its microstructure consists of a mixture of austenite and ferrite phases. As a result, Duplex 2205 Plate stainless steel sheets display the properties feature of austenitic and ferritic steels.
This combination of properties represents some compromise compared to pure austenite and pure ferrite grades. Super Duplex Plate is almost always stronger than ferritic stainless steel. In some cases, duplex stainless steels can be twice as strong as austenitic stainless steel.
Duplex 2205 Sheet is believed to be resistant to stress corrosion cracking but is less resistant to this form of attack than ferritic steel. However, the less resistant duplex stainless steels have a higher corrosion resistance than the most commonly used grades of stainless steel, namely 304 and 316.
Duplex stainless steels are also magnetic and have properties that make them easily distinguishable from common austenitic grades.
ASTM A240 / A240M
UR52N+ is a popular Super Duplex Sheet grade with high strength and excellent corrosion resistance. This grade differs in composition from 2205 stainless steel with the addition of copper. This greatly improves resistance to strong reducing acids such as hot chloride and sulfuric acid.
UR52N + is a registered trademark of the widely used Usinor Group. Other names by which it is known are given in the table below.
There are many other 254 SMO Plates, most of which are proprietary grades developed and manufactured by individual manufacturers.
The corrosion resistance of duplex stainless steel
Duplex 2507 Plate stainless steel is very resistant to corrosion. They are highly resistant to intergranular corrosion. Even in chloride and sulfide environments, duplex stainless steels are extremely resistant to stress corrosion cracking.
Heat resistance of duplex stainless steel
At low temperatures, duplex stainless steels have better ductility than ferrite and martensite grades. Duplex grades are easy to use down to -50°C.
Duplex stainless steel fabrication
All Duplex Steel Sheet production should only be done with tools specifically for stainless steel materials. Tools and work surfaces should be thoroughly cleaned before use. These precautions are necessary to prevent cross-contamination of stainless steel with metals that are susceptible to corrosion and tarnish the product's surface.
Machinability
Machining is possible, but due to the high strength of Duplex Steel Plate, machining is difficult. For example, 2205 machining is about 20% slower than 304.
You can improve machining by using the following rules.
The cutting edge should be kept sharp. Dull edges cause excessive hardening.
The incision should be light, but deep enough so that the work piece is not hardened when mounted on the surface of the material.
Tip breakers should be used to keep tips free from the worksite.
Austenitic alloys have low thermal conductivity, so heat concentrates on the cutting edge. This means you need refrigerants and lubricants, and you need to use them in large quantities.
Duplex stainless steel welding
Duplex Stainless Steel Sheet has good weld ability. All standard welding processes can be used. Welding is not as easy as austenitic grades, but dual-phase grades have the lower thermal expansion, which reduces post-weld strain and residual stress.
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