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400 Series Stainless Steel

Electropolishing Service for 400 Series Stainless Steel

Martensitic and ferritic grades electropolished to outstanding chrome-like finishes — surgical instruments, cutlery, valves, and automotive components transformed without chrome plating.

Chrome-Like
On 410 & 420
ASTM B912
Decorative Finish Spec
Up to 50%
Ra Improvement
#1
Largest EP Specialist

Able can electropolish a wide variety of stainless steel parts including 400 series. The 400 series includes both martensitic and ferritic grades, offering high strength, hardness, and moderate corrosion resistance.

After electropolishing, 400 series components achieve finishes ranging from good to outstanding chrome-like on grades 410 and 420. EP removes heat tint, oxide scale, and microscopic burrs while enriching the chromium oxide passive layer.

Unlike mechanical polishing, electropolishing reaches recessed areas, internal passages, and complex geometries uniformly.

Send us your 400 series stainless steel samples to electropolish free of charge. We’ll even pay for shipping. Samples processed and returned in a few days.

Benefits of Electropolishing 400 Series Stainless Steel

Chrome-Like
💎

Chrome-Like Finish Without Plating

Electropolishing produces outstanding chrome-like finishes on 410 and 420 grades — rivaling decorative chrome plating per ASTM B912 without the environmental and adhesion concerns of electroplating.

Up to 50%
✨

Microfinish Improvement

Removes .0005"–.001" uniformly from all surfaces, improving Ra values by up to 50%. Microscopic peaks are dissolved first, yielding a smoother, brighter surface that mechanical polishing cannot consistently achieve.

Heat Tint
🔥

Heat Tint & Oxide Scale Removal

Removes heat tint, blue oxide discoloration, and weld scale left by heat treatment, annealing, and welding — restoring the full corrosion resistance and appearance of the base alloy without mechanical abrasion.

Burr-Free
🔬

Precision Micro-Burr Removal

Eliminates microscopic burrs and machining marks from milling, grinding, and EDM — critical for surgical instruments, blade edges, and precision valve components where surface defects compromise function and safety.

Fatigue
⚙️

Enhanced Fatigue Resistance

Removes surface stress risers — micro-cracks, tool marks, and grinding damage — that initiate fatigue failure under cyclic loading. Electropolished springs, shafts, and fasteners consistently achieve longer service life.

Friction
🔩

Reduced Surface Friction & Galling

Micro-smooth electropolished surfaces reduce friction and prevent galling on mating parts — critical for valve stems, pump shafts, and threaded fasteners operating under load in 400 series stainless applications.

Before & After

Electropolishing Results: 420 SS

BEFORE EP
→
AFTER EP

420 SS — Visual Finish

Outstanding chrome-like finish after electropolishing — comparable to decorative chrome plating, achieved without plating chemicals or adhesion concerns. Heat tint and machining marks are completely eliminated.

Before: 16–20 µin RaAfter: 8–10 µin Ra
SEM: BEFORE EP
SEM: AFTER EP

420 SS — SEM Surface Topography (500×)

Scanning electron microscopy reveals how electropolishing dissolves surface peaks, eliminates machining marks, and removes embedded carbide particles — leaving a uniform chromium-enriched passive layer.

Rough: peaks, burrs, inclusionsSmooth: chrome-like passive layer

400 Series Components We Electropolish

Surgical Instruments

Scalpels, hemostats, forceps, retractors, and needle holders — electropolished to outstanding chrome-like decorative finish per ASTM B912, meeting the highest standards for medical instrument appearance and corrosion resistance.

Dental Tools & Instruments

Probes, scalers, curettes, mirrors, and explorers — electropolished for bright, corrosion-resistant surfaces that maintain sharpness, resist protein adhesion, and survive repeated sterilization cycles without degradation.

Cutlery & Industrial Blades

Chef knives, paring knives, food processing blades, and industrial cutting tools — electropolished to improve edge geometry, reduce surface friction on cut materials, and deliver the chrome-like appearance expected in premium cutlery.

Valve Bodies, Stems & Seats

Gate valves, ball valves, globe valve stems, and seats for fluid handling applications — electropolished to reduce operating friction, improve seal surface quality, and extend service life in valve components where 400 series provides adequate corrosion resistance.

Automotive & Firearms Components

Trim, exhaust hardware, barrel blanks, slides, bolt carriers, and action components — electropolished for chrome-like decorative finishes on martensitic grades and improved corrosion resistance on ferritic grades used in exterior applications.

Pump Shafts & Impellers

Pump shafts, impellers, and wear rings manufactured from 400 series — electropolished to reduce friction, improve dimensional consistency, and deliver surfaces that resist cavitation erosion and mild corrosive attack in process fluid environments.

Fasteners & Springs

High-strength bolts, pins, studs, and compression springs — electropolished to eliminate stress risers and improve fatigue life under cyclic loading, while providing the anti-galling surface needed for reliable assembly and disassembly.

Mold Cavities & Die Components

Injection mold cavities and die inserts manufactured from 420 SS — electropolished to improve surface finish, reduce part ejection friction, and deliver the chrome-like appearance required for optical-quality plastic molding applications.

400 Series Alloy Finish Results

Expected finish quality from Able's electropolishing process based on extensive production experience.

Alloy Able Finish Quality EP Benefit Typical Parts Ra Before → After

Our Electropolishing Process

1

Part Evaluation

Alloy grade, geometry, heat treat condition, and finish specifications assessed by our experts.

2

Cleaning & Prep

Oils, oxides, and machining contaminants removed. Custom racking for optimal current distribution.

3

Electropolishing

Proprietary electrolyte dissolves surface peaks uniformly. Chrome-like passive layer forms simultaneously.

4

Rinse & Dry

Thorough multi-stage rinse and controlled drying to preserve the electropolished surface quality.

5

QC & Delivery

Inspected per specification, documented, packed and shipped promptly.

Contact us to learn more about 400 Series electropolishing

Learn About the Electropolishing Difference


Electropolishing 101 Webinar

Electropolishing 101
Webinar

Learn everything you need to know about electropolishing as part of a private, interactive webinar. Let us know your availability and your part issues and our electropolishing experts can get you on our schedule.

Schedule Your Private Webinar
Try Electropolishing for Free: Sample Request

Try Electropolishing for Free:
Sample Request

Send us your parts and we'll electropolish them for free – we'll even pay for the shipping! Samples are processed and returned in a few days.

Request a Sample

Medical Device Manufacturing

Medical Device Manufacturing

From implantable devices to surgical instruments, electropolishing is a single-process treatment that results in biocompatible, safe and ultra clean parts.

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Aerospace

Aerospace

We offer aerospace vendors and original equipment manufacturers our signature metal finishing services to increase fatigue-resistance for their metal parts, rendering them capable of withstanding the stress and corrosion that comes with long-term use.

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Pharmaceutical

Pharmaceutical

Our strict adherence to industry standards ensures that pharmaceutical components are electropolished in accordance with ASTM B912 and ASME BPE specifications. These products are clean and smooth, corrosion resistant and contaminant free.

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Automotive

Automotive

Corrosion resistance and microfinish improvement are essential for critical automotive parts, making electropolishing an increasingly beneficial option for automakers.

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Consumer Appliance

Consumer Appliance

Our metal finishing services help increase corrosion resistance for these parts, and by removing the outermost layer of metal with electropolishing the durability and longevity of these appliance components is increased.

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Food & Beverage

Food & Beverage

Electropolishing materials for this industry eliminates the buildup of bacterial biofilms, as well as keeping the equipment free of contaminants like Salmonella. Electropolishing delivers the level of sanitation required by a number of regulatory agencies.

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Hydraulics & Pneumatics

Hydraulics & Pneumatics

From robotics to mobile equipment, the uses of electropolishing in the hydraulics and pneumatics industry are many. By helping prevent premature part failure, electropolishing reduces downtime and increases the life cycle of these components.

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Electronics

Electronics

Improving conductivity and performance is just one benefit electropolishing offers for electronics parts. The surface finish is improved by as much as 50%, removing imperfections from the material without material removal.

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Electropolishing, Passivation and Metal Surface Analytics Blog

High-Quality Electropolishing for Small and Intricate Parts

Metal fabrication for parts used in the medical and electronics industries can involve dimensions as small as a grain of rice — or even a strand of hair. At that scale, surface defects may be invisible to the naked eye,…

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When is Stainless Steel Passivation Required?

While stainless steel is known for its corrosion resistance, it contains iron, which is susceptible to corrosion, especially if parts are frequently exposed to moisture or harsh environments. Contamination left behind by machining processes can also impede the corrosion resistance…

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Electropolishing Specialist vs. a Local Metal Finishing Company

Electropolishing is a highly controlled electrochemical process that directly impacts surface integrity, corrosion resistance, cleanliness, and performance.

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Why Electropolishing is the Aerospace Solution for EDM Recast

In aerospace manufacturing, electrical discharge machining (EDM) is often the only practical way to create the intricate shapes, micro-features, and tight-tolerance geometries required in high-performance parts. From fuel-system components to actuator housings, landing-gear hardware, and propulsion assemblies, EDM enables precision…

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Frequently Asked Questions

What services does Able Electropolishing provide?

We provide electropolishing, nitric & citric passivation, and vacuum vapor degreasing.

What are the maximum part sizes that can be processed for electropolishing, passivation, and vapor degreasing?

Electropolishing:

  • 300 & 400 series stainless steel: 108” Length x 41” Width x 42” Height
  • Copper, brass, aluminum, steel, and nickel alloys: 72” Length x 14” Width x 17” Height (best results are achieved on parts that are no larger than 12” square)
  • Titanium, Nitinol, tungsten, and niobium, etc. (refractory metals): 26” Length x 8-3/4” Width x 9-3/4” Height

Passivation:

  • Standard nitric acid passivation: 72” Length x 30” Width x 30” Height
  • Nitric acid/sodium dichromate: 20” Length, 20” Width x 20” Height
  • Citric acid: 26” Length x 18” Width x 15” Height

Vapor degrease:

  • Vapor degrease (vacuum): 23” Length x 16” Width x 10” Height

Note: If there is a question regarding our capabilities, please email a print for review to sales@ableelectropolishing.com.

What information do you require in order to receive a quotation?

We need a copy of the drawing, service needed, lot and annual quantities, process specification and packaging requirements.

What is your standard lead-time?

Standard delivery is 3 to 5 working days after receipt of order. Next day and same day services are offered at an additional cost. Please contact our sales department for further details.

What is the difference between passivation and electropolishing?

Passivation is a chemical process designed to remove free iron and other contaminants from the part surface. Electropolishing is an electro-chemical process that removes surface metal which improves micro finish, provides deburring and adds to the aesthetics of your part.