In the production process of stainless steel screws, such as the heading process or the turning process, the surface of the screw may be stained with iron filings or some relatively written particles generated during the processing process. If these are not removed, then It will affect the appearance of the screw surface or cause the screw to rust. Generally, this kind of surface treatment needs to be passivated to remove the impurities on these surfaces.
If the stainless steel screw is passivated, it will not only make the surface of the screw smoother and brighter, but also enhance the rust resistance and corrosion resistance of the screw. Because of different passivation treatments, the salt spray test time that can be passed is different. Some can pass 24 hours, and some can pass 1000 hours. This requires the customer to proactively express how long the salt spray test will take. Otherwise, the stainless steel screw manufacturer will basically treat the screw in accordance with the standard passivation treatment.
If the stainless steel screw is processed according to the standard passivation, it can basically only pass the salt spray test for 12 hours, which cannot be longer. Therefore, when passivation is to be done, it is necessary to inform the screw manufacturer of its own requirements, otherwise the effect will be different from what you actually need.