Passivation&Electrolytic Polish-HL Parts | Ultra-high Precision Mechanical Machining Parts Manufacturer

Passivation & Electrolytic Polishing Services

Electropolishing and passivation are both processes used to enhance the corrosion resistance and surface quality of metals. Electropolishing works by stripping away a thin layer of metal, resulting in a smooth and polished finish, while passivation forms a protective oxide layer on the metal surface, which enhances both its corrosion resistance and surface roughness.

Passivation & Electropolishing of CNC Machined Stainless Steel Parts

Principle of Stainless Steel Passivation:
Passivation is a process that enhances the metal’s resistance to oxidation and slows down its corrosion rate. When corrosion products form on the metal surface due to exposure to a medium, these products can create a dense, protective film. This thin layer adheres tightly to the metal, altering its surface state and significantly increasing the metal's electrode potential. As a result, the metal enters a passive state, exhibiting corrosion resistance similar to that of noble metals. This protective layer is referred to as the passivation film.

Principle of Stainless Steel Electropolishing:
Stainless steel electropolishing is a technique aimed at improving the surface finish of stainless steel parts. The part to be polished serves as the anode, while an insoluble metal acts as the cathode. Both are immersed in an electrolytic bath, and a direct current is applied to cause selective anodic dissolution. This process gradually smooths the surface, leveling out imperfections and enhancing the overall brightness of the workpiece.

Description of Type: (Reference Standard: ASTM A967)

Stainless steel nitric acid passivation type

Types	Solution (volume percentage)	Solution temperature (℃)	Minimum immersion time (min)
Nitric 1	20% -25% nitric acid and 2.5% + 0.5% of the heavy inscription acid sodium (environmental protection)	50-55	20
Nitric 2	20%-45% nitric acid	20-30	30
Nitric 3	20%-25% nitric acid	50-60	20
Nitric 4	45%-55% nitric acid	50-55	30

Stainless steel citric acid passivation type

Types	Solution (volume percentage)	Solution temperature (℃)	Minimum immersion time (min)
Citric 1	4%-10%citric acid	60-71	4
Citric 2	4%-10%citric acid	49-60	10
Citric 3	4%-10%citric acid	20-49	20

Stainless Steel Passivation & Electrolytic Polishing Ability

Stype	Nitric Acid Passivation、Citric Acid Passivation	Electrolyte Polishing
Base material	Stainless steel series	300 series stainless steel
Standard	ASTN A967	GB/T 20016
Maximum machining size (cm)	1004580	1004580
Unit Max Weight (kg)	80	50
Color	natural color	gloss white
Test method	Boiling water test, wet cloth test, temperature experiment, the water immersion test, salt spray test, humid copper sulfate test experiment	dimensional gauging，Appearance instrumentation