Today we will be looking at magnetism and steel; and while we may not be taking the same approach that Walter Egan and Stevie Nicks did, we still enjoy their song.
It is commonly known that SS304 grade or lower is magnetic and that SS316 is not.
That being said, one question that comes up among some of our customers is whether our SS316 valves are magnetic or not?
The three key elements of stainless steel are: chromium, nickel, and molybdenum.
Chromium helps with resisting corrosion; nickel increases toughness, weldability, and ductility; and molybdenum helps with resisting pitting and crevice corrosion as well as improving mechanical properties in high temperatures.
Changing the levels of these elements or adding additional elements will alter what the valve is able to do or withstand.
There are many different designations for stainless steel that communicate the levels of these elements and what environment will be the best fit for the steel product.
For an example see this article on stainless steel 304 and 316.
Stainless steel 316 is austenitic and is one of the most corrosion-resistant varieties that you can find among standard stainless steels.
It is often used in fast moving marine environments, as well as in food production and beer brewing.
One problem with SS316 is that surface cracking occurs when casting. Because of this, additional chromium is used when casting.
Stainless steel valves use casting parts which are called CF8M.
CF8M is the cast equivalent to SS316.
It is strong, very resistant to corrosion, and able to be used at higher temperatures.
Compared to SS316 wrought grade and sheet metal, CF8M is slightly magnetic due to having higher levels of ferrite.
So the answer to the question posed in the title of this article is yes and no. Stainless steel 316 wrought grade and sheet metal are not magnetic.
Casting parts such as valves or fittings are CF8M and are slightly magnetic. Also, because they are cast equivalents, CF8M valves are commonly referred to as SS316 valves.
If you have additional questions regarding our stainless steel valves please don’t hesitate to reach out to us.