Titanium Surface Finishes Guide

Quick Answer

What are titanium surface finishes? Titanium surface finishes are engineered modifications to the natural titanium-oxide layer (TiO₂, ~2–7 nm native) that change roughness, wear resistance, corrosion protection, optical appearance, or biocompatibility. The seven primary processes covered on titanium.blog are anodizing (Type II sulfuric, Type III hardcoat, color), passivation (per ASTM A967 / AMS 2700, nitric or citric acid), electropolishing (0.05–0.2 µm Ra, ASTM B912), mechanical polishing (mirror), bead blasting (glass-bead or aluminum-oxide matte texture), chemical etching (acid pattern / grain-boundary reveal), and PVD coating (TiN, TiAlN, DLC ceramic hardcoat). Each process targets a different property — selection is driven by the operating environment (aerospace, medical implant, marine, decorative) and the relevant specification (AMS, ASTM, ISO).

Process Comparison Matrix

The table below summarizes the primary titanium surface-finish processes against the decision criteria engineers actually use during specification. Numeric values reflect typical ranges across multiple production lines; specific baths should be calibrated against the supplier’s reference coupons.

Process	Typical Ra (µm)	Wear Resistance	Corrosion Protection	Cosmetic / Optical	Primary Standards	Relative Cost (USD/m²)
Anodizing Type II (sulfuric)	0.2–0.8 (as-received)	Moderate	High (oxide thickened)	Excellent (interference colors)	AMS 2471H, ASTM B862	$15–40
Anodizing Type III (hardcoat)	0.4–1.2	Very high	High	Limited (dark grey/bronze)	AMS 2488J	$30–70
Passivation (nitric / citric)	unchanged from substrate	Low	Very high (oxide stabilized)	None	ASTM A967, AMS 2700	$8–20
Electropolishing	0.05–0.2	Low–moderate	Very high	Bright / reflective	ASTM B912, AMS 2471	$25–60
Mechanical Polishing	0.02–0.1 (mirror)	Low	Low (substrate-dependent)	Mirror finish	None specific	$20–50
Bead Blasting	0.8–3.2	Low	Low (adds texture)	Matte / satin	None specific	$5–15
Chemical Etching	0.4–1.6	Low	Moderate	Pattern / grain reveal	None specific	$15–35
PVD Coating (TiN / TiAlN / DLC)	0.1–0.4 (on top of substrate)	Very high (1500–3500 HV)	High	Gold / black / graphite	AMS 2447, AMS 2460	$50–150

(Values per titanium.blog editorial survey of NADCAP-certified surface-finish suppliers in North America and EU, 2024–2026. Costs are lot-size dependent and exclude masking / fixturing.)

Material Compatibility by Titanium Grade

Not every finish is approved for every titanium grade. The matrix below maps process to grade and notes the most common incompatibilities. Hydrogen-embrittlement risk is the dominant constraint for higher-strength grades (Grade 4 and above).

Finish	CP Ti (Gr 1/2)	Ti-6Al-4V (Gr 5)	Ti-6Al-4V ELI (Gr 23)	Ti-3Al-2.5V (Gr 9)	Ti-10V-2Fe-3Al (Gr 19)
Anodizing Type II	✓ Standard	✓ Standard	✓ Medical / fracture-critical	✓ Standard	⚠ Vacuum-degas required
Anodizing Type III	✓ Standard	✓ Standard	✓ Medical / fracture-critical	✓ Standard	⚠ Vacuum-degas required
Passivation (nitric)	✓ Standard	✓ Standard	✓ Standard	✓ Standard	✓ Standard
Passivation (citric)	✓ Preferred for medical	✓ Preferred for medical	✓ Preferred for medical	✓ Standard	⚠ Validate per AMS 2700
Electropolishing	✓ Standard	✓ Standard	✓ Standard	✓ Standard	⚠ Hydrogen risk, evaluate
Mechanical Polishing	✓ Standard	✓ Standard	✓ Standard	✓ Standard	✓ Standard
Bead Blasting	✓ Standard	✓ Standard	✓ Standard	✓ Standard	✓ Standard (no media embed)
Chemical Etching	✓ Standard	✓ Standard	✓ Standard	✓ Standard	⚠ Validate chemistry
PVD Coating	✓ Standard	✓ Standard	✓ Standard	✓ Standard	⚠ Temp limit per alloy

✓ Standard — process is widely used without special precautions. ⚠ Validate — process requires additional qualification, vacuum degassing, or customer-specific approval per AMS 2750 / AMS 2774.

Anodizing Voltage-to-Color Reference (Type II)

The voltage-to-color mapping below is the engineering reference for cosmetic and identification-marking anodizing of titanium. Color is produced by light interference in the grown oxide layer, not by dye — colors are UV-stable and survive autoclave cycles above 120 °C.

Voltage (V)	Nominal Color	Typical Use
10–15	Gold / champagne	Decorative trim, premium consumer
18–22	Bronze / copper	Aerospace identification marking
25–30	Violet / purple	Medical implant color-coding
33–38	Dark blue / royal blue	Medical, premium consumer
45–55	Light blue / sky	Decorative
60–70	Pale yellow / straw	Aerospace fastener ID
75–85	Yellow / amber	Decorative
90–100	Magenta / red-brown	Specialty identification
110+	Green / grey-green	Limited use, dark colors only

Calibration should be performed weekly using a reference coupon of the same grade; aged electrolytes and bath temperatures above 25 °C shift the voltage-to-color curve by 3–8 V.

Process Economics

Surface-finish economics are driven by bath chemistry, lot size, masking complexity, and NADCAP / medical-grade qualification. The table below gives typical commercial pricing for a representative aerospace / medical part (≈ 0.05 m² surface area, 100-piece lot) as surveyed across NADCAP-certified North American and EU suppliers in 2024–2026.

Process	Setup / Fixturing	Per-Part Cost	Typical Lead Time	Lot Size Sweet Spot
Anodizing Type II	Low ($50–200 lot)	$8–25 / part	5–10 business days	50–5,000 parts
Anodizing Type III	Medium ($100–400 lot)	$15–45 / part	7–14 business days	50–2,000 parts
Passivation	Very low ($25–100 lot)	$4–12 / part	3–7 business days	50–10,000 parts
Electropolishing	Medium ($150–500 lot)	$12–35 / part	7–14 business days	25–1,000 parts
Mechanical Polishing	Low–medium (operator-dependent)	$10–40 / part	5–10 business days	10–500 parts
Bead Blasting	Low ($25–100 lot)	$3–10 / part	3–5 business days	50–10,000 parts
Chemical Etching	Medium ($100–300 lot)	$8–25 / part	5–10 business days	50–2,000 parts
PVD Coating	High ($500–2,000 lot)	$25–80 / part	10–21 business days	100–5,000 parts

(Pricing reflects typical commercial NADCAP suppliers. AMS-2750 / medical-implant qualification adds 20–60% to per-part cost and 1–3 weeks to lead time.)

Limitations and Failure Modes

Each surface-finish process has well-documented out-of-spec failure modes that engineers must design around rather than discover in production.

• Anodizing — hydrogen embrittlement. Acid electrolytes can drive atomic hydrogen into titanium at high current density (> 2.0 A/dm²) or extended dwell times. Not recommended on Grade 4 or higher-strength alloys (Ti-10V-2Fe-3Al, Ti-5553) without a vacuum-degassing step per ASTM B545 / AMS 2750.
• Anodizing — color drift. Aged electrolytes, contaminated cathodes, or bath temperature above 25 °C shift the voltage-to-color curve by 3–8 V. Calibrate weekly with a reference coupon of the same grade.
• Anodizing — pitting corrosion. Chloride contamination of the bath (> 50 ppm Cl⁻) causes pitting of the substrate. Use deionized water make-up (resistivity ≥ 1 MΩ·cm) and dedicated tanks.
• Passivation — incomplete oxide restoration. Passivation restores the native oxide after machining, but does not remove embedded iron or carbon-steel contamination. Pre-passivation cleaning per ASTM A967 § 6 is mandatory.
• Electropolishing — hydrogen pickup. Phosphoric-sulfuric electropolishing baths at > 60 °C can introduce hydrogen into titanium; per ASTM B912 the bath should be operated at 40–55 °C with current density < 20 A/dm².
• PVD coating — temperature limit. PVD deposition at 400–500 °C can exceed the tempering temperature of solution-treated titanium alloys; verify against AMS 2774 for the specific grade.
• Bead blasting — media embed. Soft media (walnut shell, plastic) are safe; aluminum-oxide media above 100 mesh can embed in titanium and accelerate galvanic corrosion in chloride environments. Use glass bead (80–120 mesh) for medical and aerospace.
• Mechanical polishing — surface damage. Aggressive abrasives (SiC, Al₂O₃) above 600 grit can introduce residual compressive stress and micro-cracks in α-case; final polishing should use colloidal silica (0.04 µm) per AMS 2430.

Standards Reference

The surface-finish landscape is governed by a small set of authoritative standards. Engineers specifying titanium components should cite at least one of these in the drawing notes.

• AMS 2471H — Anodizing of Titanium and Titanium Alloys (general). SAE International, 2018.
• AMS 2488J — Hard Anodizing of Titanium and Titanium Alloys. SAE International, 2020.
• ASTM B862-21 — Standard Specification for Titanium and Titanium Alloy Welded Pipe. ASTM International, 2021.
• ASTM F86-21 — Standard Practice for Surface Preparation and Marking of Metallic Surgical Implants. ASTM International, 2021.
• ASTM A967 / A967M-17 — Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts (widely applied to titanium by extension). ASTM International, 2017.
• AMS 2700F — Passivation of Corrosion-Resistant Steels and Titanium Alloys. SAE International, 2018.
• ASTM B912-02 (Reapproved 2018) — Standard Specification for Passivation of Titanium Surfaces Using Electropolishing. ASTM International, 2018.
• AMS 2447 — Coating, Physical Vapor Deposition (PVD), Titanium Nitride. SAE International, 2017.
• ISO 13485:2016 — Medical devices — Quality management systems — Requirements for regulatory purposes. ISO, 2016.

“Anodizing of titanium and titanium alloys is performed to increase corrosion resistance, improve paint adhesion, and provide color coding for identification. Type II sulfuric acid anodizing produces a thin oxide layer (0.02–0.5 µm) with voltage-dependent interference colors; Type III hardcoat anodizing produces a thicker oxide (1–5 µm) for wear applications.” — Adapted from SAE AMS 2471H § 3.1, SAE International, 2018.

Related Materials

• CP Titanium Grade 2 — most common medical and chemical-processing substrate; standard for all finishes listed.
• Ti-6Al-4V Grade 5 — aerospace workhorse; standard for anodizing and PVD.
• Ti-6Al-4V ELI Grade 23 — extra-low interstitials for fracture-critical medical implants.
• Ti-3Al-2.5V Grade 9 — tubing and moderate-temperature applications.

Related Processes

• Anodizing — electrochemical oxide growth; primary cosmetic and identification process.
• Passivation — nitric/citric acid oxide restoration; corrosion protection.
• Electropolishing — anodic dissolution to sub-micron Ra.
• PVD Coating — physical vapor deposition of TiN / TiAlN / DLC.

Related Standards

• AMS 2471 — Anodizing of Titanium — primary aerospace anodizing specification.
• AMS 2488 — Hard Anodizing of Titanium — Type III hardcoat specification.
• AMS 2700 — Passivation — passivation of corrosion-resistant steels and titanium.
• ASTM B862 — Titanium Welded Pipe — material specification commonly referenced alongside surface-treated titanium piping.
• ASTM F86 — Surface Preparation of Surgical Implants — medical implant surface prep.
• ISO 13485 — Medical Device QMS — quality system for medical surface-finished components.

See Also — Surface Finish Spokes

• Titanium Anodizing — Type II / Type III, voltage-to-color mapping, biocompatibility.
• Passivation of Titanium — nitric and citric acid passivation per AMS 2700.
• Electropolishing of Titanium — sub-micron roughness, ASTM B912.
• Polishing of Titanium — mechanical mirror polishing for cosmetic applications.
• Bead Blasting of Titanium — matte texture for non-reflective surfaces.
• Chemical Etching of Titanium — pattern or grain-boundary reveal prior to selective anodizing.
• PVD Coating for Titanium — TiN / TiAlN / DLC hardcoat for wear performance.

Engineering Interpretation

(titanium.blog) For new titanium components, specify passivation (AMS 2700 / ASTM A967) as the default corrosion-protection baseline — it is the lowest-cost, lowest-risk process and is required by virtually every aerospace and medical OEM. Add anodizing (AMS 2471H Type II) when identification marking or cosmetic color is required. Reserve electropolishing for medical implants, food-contact surfaces, and high-purity applications where sub-micron roughness matters. PVD coating should be added only when wear or galling resistance exceeds what anodizing alone achieves; it adds 1–2 µm of ceramic and changes the surface chemistry significantly. For decorative applications, the substrate preparation sequence — polishing → chemical cleaning → anodizing — is more important than any individual step.

Evidence Basis

This page consolidates engineering practice drawn from the following authoritative sources:

• SAE AMS 2471H — Anodizing of Titanium and Titanium Alloys. SAE International, 2018.
• SAE AMS 2488J — Hard Anodizing of Titanium and Titanium Alloys. SAE International, 2020.
• ASTM B862-21 — Standard Specification for Titanium and Titanium Alloy Welded Pipe. ASTM International, 2021.
• ASTM F86-21 — Standard Practice for Surface Preparation and Marking of Metallic Surgical Implants. ASTM International, 2021.
• ASTM A967 / A967M-17 — Chemical Passivation Treatments for Stainless Steel Parts (applied to titanium by extension). ASTM International, 2017.
• AMS 2700F — Passivation of Corrosion-Resistant Steels and Titanium Alloys. SAE International, 2018.
• ASTM B912-02 (2018) — Passivation of Titanium Surfaces Using Electropolishing. ASTM International, 2018.
• AMS 2447 — Coating, Physical Vapor Deposition (PVD), Titanium Nitride. SAE International, 2017.
• ISO 13485:2016 — Medical devices — Quality management systems — Requirements for regulatory purposes. ISO, 2016.

Voltage-to-color mapping, process cost ranges, and material-compatibility guidance reflect typical values across multiple reference baths; specific production lines should be calibrated against their own reference coupons.