Should Stainless Steel Screws Be Passivated?

After production, many stainless steel screws are simply cleaned and packaged for shipment. So, do they need to undergo passivation treatment? In fact, although stainless steel screws have excellent rust resistance, they still require some form of passivation. We know that carbon steel screws are protected from rust through surface treatments such as electroplating or other methods that isolate them from the air. Stainless steel screws, however, due to the different properties of the material, can be used directly in open air. Yet, in particularly harsh environments, stainless steel screws can still rust. To enhance their rust resistance, we can subject them to a passivation treatment to improve their anti-corrosion performance.

Passivation involves immersing the stainless steel screws in a passivation solution. This solution is suitable for all 200, 300, and 400 series stainless steel materials. After passivation, the oxidation resistance of the stainless steel screws is significantly improved. For unpassivated stainless steel screws, the salt spray test duration is 48 hours; however, for passivated stainless steel screws, can reach 72 hours in salt spray testing.

If the stainless steel screws lack luster and this cannot be removed during cleaning, a single passivation treatment can also improve the surface gloss of the screws.