What is hard chrome plating used for?

Hard chrome is used to build up and salvage worn or undersized parts, improve wear resistance, enhance lubricity, and extend service life on components like shafts, rods, rolls, molds, and dies.

How is final size achieved after hard chrome plating?

Deposits are applied oversize and then ground, honed, or lapped to final dimension and surface finish per the drawing.

Is hard chrome the same as decorative chrome?

No. Decorative chrome is thin and cosmetic, typically over nickel systems. Hard chrome is a functional, thicker deposit for performance and dimensional restoration.

Armoloy Coatings

Hard Chrome Plating

Build up, salvage, and protect. Hard chrome plating provides thick, durable deposits that improve wear resistance, enhance lubricity, and restore worn or undersized parts for extended service life.

Hard chrome is processed exclusively at our Armoloy Fort Worth fulfillment center for precision and consistency

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Armoloy Coatings

What is Hard Chrome Plating?

Hard chrome plating (also called engineering or industrial chromium) is the electrodeposition of metallic chromium onto a part to boost wear resistance, reduce friction, restore dimensions, and resist galling. It’s specified widely in aerospace, energy, heavy equipment, and tooling when parts face sliding/rolling contact, abrasion, or erosive media. Unlike decorative chrome, hard chrome is a functional coating—often applied thicker and then ground/honed to final size.

Chromium deposits are typically micro-cracked—a natural outcome of internal tensile stresses during deposition—which is key to wear behavior; crack density depends on chemistry and process. Thin or specially formulated deposits can be crack-free/micro-nodular (often called thin dense chrome, TDC) when extremely tight tolerances and improved barrier properties are the priority.

ASTM A967 compliant passivated steel flange

Types of Chrome Coatings

Engineering (hard) chromium vs. decorative chromium

Functional hard chrome is designed for wear and dimensional control (often thick, then ground). Decorative chromium is thin and primarily cosmetic, typically over nickel systems.

Deposit structures used in engineering chrome (per ISO 6158)

Micr-cracked chromium (typical hard chrome).
Micro-porous chromium (often produced by special treatments to hold lubricant).
Crack-free/ specially profiled deposits for barrier performance or tight fits.

Thin Dense Chrome (TDC) variants

Very uniform, thin, and either micro-cracked or micro-nodular/crack-free depending on process—useful where tight tolerance and consistent coverage on complex shapes are critical.

part surface examination at Armoloy Illinois

Performance Characteristics

Hard Chrome by the Numbers

Hardness: ~900–1100 HV (≈ HRC 66–70) depending on bath and process
Typical thickness range (functional): 0.0001–0.030 in (≈ 2.5–760 μm), with many wear surfaces in the 0.0005–0.002 in range
Coefficient of friction (against steel): about 0.21 dry and ~0.16 lubricated (application-dependent)
Microcrack density (typical hard chrome): often on the order of hundreds of cracks per linear inch; “crack-free” or micro-nodular TDC variants are engineered to reduce/alter crack networks
Corrosion behavior: Because hard chrome is commonly micro-cracked, barrier corrosion resistance by itself is limited; using suitable undercoats (e.g., nickel) or heavier deposits improves barrier performance
Fatigue considerations: Conventional hard chrome can debit fatigue strength of high-strength steels; stress-relief before plating and post-plate hydrogen bake per standards—and shot peening—are widely used mitigations

Ultra-hard metallic surface, low friction, excellent wear and scuff resistance
Can restore undersize parts and then be ground/honed back to tolerance
Works on OD/ID geometries using conforming anodes and masking/fixturing

Hydraulic rods and cylinders, piston rods, pump shafts, rolls, rams, and plungers
Tooling: molds, dies, punches, and gauges

Hard Chrome Features & Benefits

Great wear resistance

Dense metallic chromium withstands abrasion/erosion in high-load contact conditions

Low friction + anti-galling

Reduces adhesive wear and helps parts run cooler; further lowered with lubrication or surface texturing

Dimensional restoration

Build up worn/undersize regions, then grind/hone to blueprint

Thermal + chemical durability

Metallic Cr/Cr₂O₃ surface resists many chemicals and holds up under typical service temperatures for steel components (application-specific)

Hard Chrome Plating Process

How We Chrome Plate for Quality & Repeatability

1. Pre-plate inspection & prep

Identify defects; chrome replicates and can exaggerate base metal marks. Parts may require grind/polish or weld dot-repair before plating.

2. Stress relief (pre-bake) for high-strength steels

Minimizes existing tensile stresses that, combined with plating tensile stress, can promote cracking; parameters per spec (e.g., AMS 2406 references AMS2759/9).

3. Cleaning & activation

Degrease/alkaline clean; verify water-break-free surface; reverse etch to activate.

4. Masking

Tape, lacquers, plugs, wax; shields, and robbers to control current density, coverage, and edge build-up.

5. Electroplating (chromic-acid/sulfate or alternative chemistries)

6. Rinse + post-plate hydrogen embrittlement relief

Bake high-strength steels promptly after plating per ASTM B850/customer spec; a common practice is ~375 °F (190 °C) for several hours (spec-dependent).

7. Finish to size

Grind/hone/lap to tolerance and surface finish; verify thickness and adhesion per the callout.

8. Quality & compliance

Thickness and adhesion tests per AMS/ASTM; documentation for stress-relief, bake cycles, and process control maintained to spec.

Additional Metal Treatments

Explore All Products

TDC

Nodular Thin Dense Chrome

Our thin dense chrome plating reduces the wear, friction and corrosion of components with a nodular finish.

TDC

Diamond Chrome Plating

For applications with particularly high wear rates, Diamond Chrome Plating XADC provides an exceptional option to alternative metal surface treatments.

TDC

Microcracked Thin Dense Chrome

Microcracked thin dense chrome plating offers a proprietary chemistry of pure chromium that increases both hardness and wear resistance.

TDC

Microcracked Thin Dense Chrome For Aluminum

AL-COAT ensures premium protection for aluminum alloys by providing a high-chromium coating that is also both dense and non-magnetic.

TDC

ME-92 Biocompatible Chromium

Biocompatible chromium medical coating, known as ME-92, brings high-precision medical industry solutions throughout the world.

TDC

BIO TDC Surgical Coating

Explore BIO TDC surgical coating for medical devices. Armoloy metal surface treatments are certified for a variety of industries.

Nickel

Mid-phos Electroless Nickel Coating

For intricate applications susceptible to corrosion, our mid-phosphorus Electroless Nickel coating offers precise, uniform coverage for long-lasting preservation.

Nickel

High-phos Electroless Nickel Plating

Armoloy's High Phosphorus Electroless Nickel plating offers great corrosion resistance for components operating in acidic environments.

Services at Armoloy

The Armoloy Corporation is here to provide support for your project, starting from the discovery phase and continuing through a successful production launch. Whether coatings are considered during the initial part design phase or become necessary due to product failures in the field, our team can assist you at any stage in the process.

armoloy corporate laboratory testing chrome solution for metal surface treatment

Research & Development

Fully equipped R&D plating lab for test runs, prototyping, and continual development of our plating technologies. Our turnkey approach ensures high-quality outcomes for your project.

Process Development & Validation

Support from design to product launch with coating selection, prototyping, testing, PPAP validation, and plating production on any scale. We also support a range of ASTM and AMS test methods with a NADCAP-certified laboratory.

Fulfillment

Armoloy ensures the development of a robust plating process that can be distributed to one of our 15 plating facilities. We’ll handle prototyping, process validation, and much more.

How Metals Fail

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Some of the most common metal failures include:

Armoloy’s different metal coating solutions help industries avoid costly metal failures and unplanned downtime.

Galvanic Corrosion

Abrasive Wear

Rolling Contact Fatigue

Erosion-Corrosion

Dealloying

Pitting Corrosion

Need smooth, reliable protection? Let’s coat with precision.

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