2024-11-22
Stainless steel-The Magnet Test for Stainless Steel is Not Accurate
We apply an electrocleaning surface treatment to our stainless caster models K3, 3, 3A, and 9. It does not necessarily prevent the stainless steel from picking up iron particles as the result of how it is handled or stored. We apply an additional passivation treatment only to our stainless caster model G15 using nitric or mild organic acids to enhance the protective nature of the natural, air-formed film. Nitric acid treatment enhances the level of chromium in the protective film on stainless steel. This passivation treatment also makes it easier to remove rust if it were to occur.The stainless steel we commonly use in our stainless casters is 304. After cold work (the process of stamping, forming, surface polishing, etc) a stainless caster usually becomes magnetic in the worked areas. These areas are relatively prone to rust in a corrosive environment. If it is necessary, annealing is the most effective way to restore non-magnetic property and enhance corrosion resistance. Actually it changes martensite back to austenite. In this process the stainless product is heated to 1800F – 2100F and cooled down slowly. If the temperature is not high enough the corrosion resistance of the stainless will be reduced. This process increases cost a lot. The passivation process washes away free particles and forms a passive coating on the stainless surface. This process is what we do for only stainless caster model G15. It is a relatively economic way to enhance corrosion resistance, but it is not meant to completely restore non-magnetic property.