Stainless Steel Workshop: Ferritic stainless steels

Q: What are the advantages of ferritic stainless steels?

A: When a fabrication requires corrosion resistance and high performance, your foremost concern is its affordability. One metal that can meet this demand is ferritic stainless steel. Grades include AISI type 409, 11CfCb, 430, 436, 439, and 18CrCb, just to name a few. Whichever grade you choose, ferritic stainless steel may just offer the best metallurgical option.

Ferritic stainless steels have added chromium, titanium, and niobium for a variety of functional purposes. The single greatest advantage is their corrosion resistance. In addition, ferritic stainless has an inherently higher strength level than carbon steels, which allows the use of thinner materials, thus reducing the overall weight of the component. The chromium addition (11 percent to 20 percent) provides improved scaling at elevated temperatures, between 300 degrees and 700 degrees F. Very few similar metals offer this advantage.

The applications for ferritic stainless include heat exchanger components and furnaces, as well as automotive exhaust systems and components.

Fabricating ferritic stainless steel not only has practical implications, but affords you many financial advantages. A fabricator’s choice would undoubtedly be either GMAW or MCAW. Because there is little to no nickel present in the base metal, the cost of ferritic stainless steels is not affected by the rising cost of nickel.

We will explore the weldability of ferritic in the next issue. My advice to you is to do your homework and plan well. How you weld ferritic stainless steels involves a choice—make it wisely.