Where the
world gathers for metal finishing
Q&As since 1989


-----

Making stainless steel 304 nonmagnetic

We are manufacturing stainless steel balls. Customer wants them to be nonmagnetic. We therefore pass it through heat treatment process to make them nonmagnetic. However in furnace due to distortion we have to do additional material removal process of several microns.Generally we grind the balls but in grinding balls become magnetic again. What should we do so that balls become nonmagnetic and further processing is not to be carried on surface or is there a way in which balls do not become magnetic in grinding?

Mr Doshi
- Mumbai, India
 

---

Mr Doshi,

You need a chemical composition of stainless steel that is more austenitically stable if your manufacturing process is causing them to become ferromagnetic, due to deformation which causes the austenite to transform to martensite.

In India you are fortunate that 201 is available. Use a 201 in which nitrogen, managanese, nickel and chrome are at the highest allowable levels. If that's not possible, and you're stuck with 304, do the same thing. Raise carbon, nitrogen, chrome and nickel levels to increase austenite stability. 201 is much more cost effective.

Dr._Michael McGuire
- Pittsburgh, Pennsylvania, USA
 

---

Dear Sir,

As I understand, sst 304 should be non-magnetic itself. It may be lightly magnetised during cold work or fabrication. You can pass it through some demagnetiser to take off its residue magnetism.

Angus Chow
- Hong Kong