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Duplex 2205 VS 316 Stainless Steel

316 stainless steel is a common material, widely used in petrochemical, fertilizer plants, shipbuilding and other industries. The application of duplex steel 2205 is becoming more and more extensive, especially in offshore oil, seawater desalination and other fields with high corrosion requirements. Whether to use 316 stainless steel pipe or duplex pipe is a problem that our customers often encounter. This article briefly introduces the differences between duplex 2205 and 316 stainless steel. I hope it will be helpful to you.

The Chemical Difference Between Duplex 2205 and 316 SS

316 stainless steel is widely used in the chemical industry due to its excellent corrosion resistance. It has 2-3% molybdenum element, and belongs to the derivative of 18-8 austenitic stainless steel. As for Duplex 2205, it has been added with nitrogen to improve its partial corrosion resistance. And the solid solution tissue in ferrite and austenite has occupied each half, at least one of them shall reach 30%, which makes it perform the characteristics of ferrite and austenitic stainless steel.

The Differences  Between Duplex 2205 and 316 Stainless Steel

  • a) The yield strength of duplex 2205 is one time higher than 316L, and it has enough plastic toughness for molding. And the wall thickness of the pressure vessel made of duplex 2205 is 30-50% thinner than that of 316L, which can save the cost.
  • b) Duplex 2205 performs excellent on stress corrosion resistance, especially when it is used in the marine environment containing chloride ions. However, stress corrosion is a prominent problem to solve for austenitic stainless steel including 316L.
  • c) Duplex 2205 performs a better corrosion resistance than 316L does in many mediums. It performs a very high corrosion resistance in acetic acid, formic acid, and even can be a replacement of austenitic stainless steel, and corrosion resistant alloy. However, to choose duplex 2205 or 316L, it is still determined by the environmental needs and cost.
  • d) Duplex 2205 has high strength and ideal local corrosion resistance, wear corrosion resistance and corrosion fatigue performance, which are better than 316L stainless steel.
  • e) The linear expansion coefficient of duplex 2205 is lower than 316L, and it is close to carbon steel. This makes duplex 2205 be suitable for carbon steel connection, bringing a great significance for engineering.
  • f) No matter it is under dynamic or static load conditions, duplex 2205 has a higher energy absorption capacity than 316L, which brings obvious advantages and practical application values for structural parts or pipes when dealing with emergencies such as impact, explosion.
duplex 2205 pipe

The Disadvantages of Duplex 2205

With so many advantages, duplex 2205 seems to be superior than 316. However, compared with 316, duplex 2205 also has the disadvantages:

  • a) The application of duplex 2205 is not as universal or diversified as 316L. For example, if one requires to work under the temperature below 250 degrees for long period of time, then only 316L stainless steel can be competent.
  • b) The plastic toughness of duplex 2205 is poorer than 316L, and it also performs worse in cold processing and forming.
  • c) Duplex 2205 has medium temperature brittleness, and the heat treatment and welding process system need to be strictly controlled, so that to avoid harmful phase to appear, causing damage.
    • d) Compared with austenitic stainless steel, the weakness of duplex stainless steel is that it contains a large amount of ferrite tissue.

Duplex 2205 VS 316 SS Cost

Some people may think that the price of duplex steel is very high, much higher than 316 stainless steel. In fact, it depends on the product. Compared with stainless steel pipes, the prices of duplex steel 2205 pipe and 316 stainless steel pipe are similar, the difference is not more than 3,000 US dollars per ton.

But for pipe fittings, because of the characteristics of duplex steel, its manufacturing process is more complicated and difficult. The price of duplex pipe fittings is more expensive than that of 316 stainless steel pipe fittings.

We supply both duplex 2205 and 316 SS pipe and fittings, you are welcome to contact us if there are any requirements.