Passivation is a non-electrolytic process that typically uses nitric or citric acid to remove free iron from the surface of stainless steel. By removing this free iron— which often comes from machining tools or environmental exposure—the process allows the material’s natural chromium content to react with oxygen, forming a dense, transparent protective oxide layer. This ‘passive’ layer is what makes stainless steel truly stainless. Without proper passivation, stainless steel can experience localized pitting or surface rust in demanding environments. At AGS, our passivation processes comply with ASTM A967 and AMS 2700 standards. We handle 300-series and 400-series stainless steels, along with precipitation-hardened (PH) alloys. The treatment is essential for medical surgical instruments to ensure biocompatibility and for aerospace fluid fittings to prevent contamination. Our quality verification includes copper sulfate testing and humidity chamber exposure.