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Duplex Stainless Steel: How Does it Respond to Stress Corrosion Cracking

by Apr 8, 2019News

When using stainless steel components in corrosive environments, it’s important that you are ever-cognizant of stress corrosion cracking. This is the phrase used to describe the cracking of stainless steel while in the midst of corrosive environments.

There are a number of stainless steel alloys that are resistant to stress corrosion cracking, but duplex stainless steel (S31803 or 2205) is among the best of the readily available alloys. Interested in learning more about stress corrosion cracking in duplex stainless? Read below!

What Exactly is Stress Corrosion Cracking?

Stress corrosion cracking, or SCC, is the phenomenon in which metals crack under corrosive and physically stressful conditions. The more corrosive and more stressful an environment is, the greater physical impact it will have on metals that exist within it.

When it comes to stress corrosion cracking, not all stainless steels are created equally. Some stainless steels may be corrosion-resistant, but vulnerable to physical stress. Conversely, other stainless steels may be physically strong, but vulnerable to corrosion.

At the same time, however, there are stainless steels that are resistant to both physical stress and corrosion. These stainless steels possess the highest resistance to stress corrosion cracking.

Stress Corrosion Cracking in Duplex

As far as stress corrosion cracking goes, duplex stainless steel is one of the best stainless steels on the market today. This material thrives through all types of corrosive environments, including chloride-rich environments, sulfate-rich environments, and more.

To truly illustrate the stress corrosion cracking resistance in duplex stainless steel, you can simply look at its PREN (Pitting Resistance Equivalent Number). Duplex stainless steels typically possess PRENs of 35 and above. In comparison, austenitic and ferritic stainless steels typically possess PRENs of 30 and below.

If you’re looking for a stainless steel that will thrive in corrosive environments, duplex stainless steel is the steel to choose.

How Does it Compare to Other Types of Stainless Steel?

As you might know, duplex stainless steel consists of both ferritic and austenitic stainless steel. As such, it possesses characteristics that are present in both ferritic and austenitic stainless steel alloys.

Because of this, you might expect that ferritic, austenitic, and duplex stainless steel possess the same resistance to stress corrosion cracking. However, while there are some similarities in stress corrosion cracking between the three, there are quite a few differences as well.

To illustrate these differences, we’re going to discuss stress corrosion cracking in both austenitic and ferritic stainless steel.

Stress Corrosion Cracking in Austenitic Stainless

Possessing very high nickel content, austenitic stainless steel does a good job of resisting stress corrosion cracking in non-chloride environments. In chloride-rich environments like the ocean, however, it’s highly vulnerable to stress corrosion cracking.

For this reason, it’s not typically used for undersea purposes. In fact, one of the reasons duplex exists in the first place is to provide austenitic-like qualities but with substantially greater resistance to stress corrosion chloride cracking.

Stress Corrosion Cracking in Ferritic Stainless

Ferritic stainless steel is fairly resistant to stress corrosion cracking in all types of environments. When compared to austenitic stainless steels, it does a much better job of handling chloride. For this reason, you’ll often see it in the ocean.

However, when compared to duplex stainless steel, ferritic stainless steel falls short, offering much less resistance to all types of stress corrosion cracking.

Looking to Buy Duplex Stainless (S31803 or 2205) Steel Items?

Do you have a need for duplex stainless steel items? If so, Great Plains Stainless is the company to call.

We sell a number of different duplex components, including but not limited to bars, pipes, fittings, and flanges. These components are available in a number of different sizes and can be shipped anywhere throughout the world.

Contact us now to discuss your needs!