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Can shotblast magnetize steel?

March 28, 2008

We manufacture a sensor from carbon steel (flanges and a tube) then we powder coat.

Metal preparation is shot blast prior to finishing.

As the sensor is used to measure magnetic fields can the shot blast action magnetize the steel tube?

Phil Szarko
Product Designer - Cheltenham, Glos, UK

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Technically speaking, just about any metal can be magnetized IF the molecular structure/ pattern can be aligned or re-aligned in a one directional mode. That is why drawn stainless steel wire is used in magnetic mass finishing equipment. I think it would be highly unlikely that blasting can or will re-orient the metal structure enough to effectively magnetized.

AF Kenton
retired business owner - Hatboro, Pennsylvania
April 3, 2008

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Yes it can. For instance many 300 series austenitic stainless, such as 304, can become slightly magnetic after being cold worked, such as when shot blasted. Interestingly, not all 300 series steel are prone to this, for instance, 310 doesn't readily undergo the transformation. The change from non-magnetic to magnetic is due to small amounts of martensite being formed, which is more commonly found in 400 series stainless and is usually associated with magnetism. It can be corrected by briefly heating the steel to 700-800 °C, reconverting the martensite to austenite.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
April 8, 2008