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(773) 277-1600 | How electropolishing removes surface defects and contamination to deliver corrosion resistance, precision, and finish beyond passivation alone.
One of the most common applications for electropolishing is enhancing corrosion resistance in parts made from a wide variety of metal alloys, especially stainless steel.
Passivation can restore contaminated stainless steel to original specifications, but testing has shown that electropolishing leaves metal parts with 30x more corrosion resistance than passivation alone.
For OEMs in aerospace, medical device manufacturing, automotive, marine and other industries where part failure is not an option, electropolishing helps parts pass stringent salt spray and humidity tests by removing a precise layer of surface material, including imperfections and contaminants that can become initiation sites for corrosion.
Unlike passivation, electropolishing removes metal at a controlled microscopic level, improving surfaces that are contaminated, rough, corroded, or difficult to polish mechanically.
300 series, 400 series, and precipitation-hardening stainless steels can be electropolished without distortion, flash attack, or hydrogen embrittlement.
Electropolishing removes contamination and defects left behind by machining, welding, or brazing, creating a high-quality surface finish with tight precision.
The process delays oxidation for non-ferrous metals while deburring and improving microfinish for function and appearance.
Electropolishing can improve corrosion resistance for copper, brass, aluminum, carbon steels, and specialty alloys where passivation may not be suitable.
Electropolishing uses a modified electrical current and a chemical bath to dissolve a precise, even layer of surface material. The process is often described as the reverse of electroplating.
As current is applied, metal ions are removed from the part surface and drawn toward the cathode. The electrolyte maintains the dissolved metals in solution, and gassing at the surface furthers the cleansing process.
AC current is converted to low-voltage DC current in a rubber-lined steel tank containing the chemical bath.
Copper or stainless steel cathode plates are installed on the negative side of the power source.
Parts are fixed to a rack made of titanium, copper, or bronze and connected to the positive side.
After processing, parts are cleaned and dried to remove clinging electrolytes, leaving an ultraclean, bright surface.
Independent ASTM B-117 salt spray testing demonstrates how electropolished parts resist visible corrosion compared with raw and passivated parts.
Stainless steel samples: Electropolished stainless steel samples showed superior corrosion protection versus raw parts, with no visible signs of rust after 888 hours of salt spray exposure.
Auger and wire weldment: Raw and passivated wire weldment parts developed red corrosion after 72 hours, while the electropolished part showed no visible corrosion at that point.
Food processing component: A cold-drawn part displayed corrosion at 24 hours, while a cold-drawn and electropolished part resisted corrosion until 165 hours. A milled and electropolished version showed no corrosion during testing.
Download the full whitepaper to review the corrosion-resistance benefits, process details, and salt spray testing results.
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