My customer is inquiring about a SS deck screw, and he asks this:
Is it possible to manufacture this screw geometry in US 410 (hardened stainless steel) incl. surface 2x passivated?
He is telling me that their current Taiwanese supplier passivates the screws once before heat treatment and again after heat treatment. I have never heard of passivation done twice on the same screw. Is this really necessary? My understanding is that passivation forms a protective layer and is done in the last step of production. Any advice?
Passivation is done twice mostly for self drilling screws (using heat treated 410 for hardness), since for A2 you do not heat treatment them and therefore passivation is only done once as the final production step.