Passivation

During forming, machining, tumbling, lapping and other operations performed in the manufacture of stainless steel products, microscopic particles of iron may be embedded in or deposited on the surfaces of these products. If allowed to remain, the iron particles provide corrosion sites that will ultimately result in accelerated corrosion of the product. In order to prevent this corrosion, semi-finished or finished parts are given a passivation treatment. The passivation process consists of immersing the stainless steel in a solution of citric acid, nitric acid, or nitric acid plus oxidizing salts which dissolves the embedded or deposited iron and restores the original corrosion-resistant surface (a thin, transparent oxide film).

Selection of the correct passivation process is determined by the stainless steel alloy involved and by the specification requirement of the OEM. SCPCI has incorporated most alloy specific passivation processes as specified by AMS-QQ-P-35, and ASTM A967 to meet our customers’ needs. Many OEM passivation specifications are derived from these guiding documents. SCPCI passivation processes include nitric acid, nitric acid with oxidizing salts, and citric acid. These processes comply with many OEM specific standards. SCPCI Sales Engineering assists our customers with selection of the passivation process that will comply with applicable OEM requirements. The SCPCI database shop order system assures the same passivation process which has been selected will be specified each and every time the job comes to our shop.