When it comes to stainless steel screws, they are not unfamiliar. After production, many are cleaned and packaged for shipment directly. But do they need further passivation treatment? In fact, although stainless steel screws have strong rust resistance, some passivation treatment is still necessary. We know that the rust resistance of carbon steel screws comes from electroplating or other surface treatments, which essentially involves covering the screw with a protective layer to isolate it from air.

Stainless steel screws, due to their material properties, can be used exposed to the air directly. However, in particularly harsh environments, stainless steel screws can also rust. To enhance their rust resistance, we can subject the stainless steel screws to a passivation treatment to improve their anti-rust effectiveness.

During the production process of stainless steel screws, such as during the heading or turning operations, the screw surface may become contaminated with iron shavings or finer particles generated during the manufacturing process. If these particles are not removed, they can affect the aesthetic appearance of the screw surface or lead to rusting.

Typically, this involves a passivation surface treatment to remove surface impurities. Passivation treatment refers to soaking stainless steel screws in passivation solution. Standard passivation solutions are sold in buckets, and most chemical factories carry them. Passivation solution is also a necessary material for stainless steel screw manufacturers; it is suitable for all 200, 300, and 400 series stainless steel materials.

Passivated stainless steel screws exhibit significantly improved anti-corrosion capabilities. Without passivation, the salt spray test duration for stainless steel screws is 48 hours. However, after passivation, the salt spray test time extends to 72 hours, demonstrating a notable enhancement in effectiveness.