Zinc Plating Cr3+
Cr3+ zinc plating service · RoHS-safe
Cr3+ zinc plating service for customer-supplied screws, nuts, bolts and small fasteners. Barrel-plated, eco-safe, EU-export ready.
One plant in Samut Sakhon, ThailandSmall steel parts in bulk — screws, nuts, boltsQuote within 24 hours
Technical details
- Barrel and rack plating
- Coating thickness: 5–25 µm
- Passivation: Cr3+ Clear/Blue, Yellow, Black
- Salt-spray resistance: 96–240 hours
- Thickness verified by X-ray Fluorescence
Which zinc plating is EU-export ready for fasteners?
V.S. Heat Treatment zinc-plates small steel parts — M4–M16 screws, nuts and bolts — with Cr3+ (trivalent, Cr6-free) barrel plating at its one plant in Samut Sakhon, Thailand, in clear/blue, yellow iridescent and black finishes that meet RoHS/REACH. High-strength parts are baked against hydrogen embrittlement in-house and coating thickness is checked by X-ray. The plating line shares the plant with a hardening line that runs over 2,000 tons a month; work is priced by weight, not per piece, every lot ships with a certificate under ISO 9001:2015, and quotes are answered within 24 hours. The plant does not take large gears, shafts, mould inserts or one-off large workpieces. Its own transport collects and delivers in Samut Sakhon, Bangkok, Samut Prakan, Nakhon Pathom, Chon Buri, Rayong and Chachoengsao; from other provinces, parts come in by parcel freight or the customer’s own transport.
Last updated
Capacity & specs
- Part size
- M4 – M16
- Lead time
- By agreement
- MOQ
- Flexible
Standards we work to
The named standards buyers specify — the applicable standard, class and service condition are confirmed against your drawing and order.
ASTM B633
Zinc electroplating — Types II/III, service conditions SC1–SC4 (5–25 µm).
ASTM F1941 / F1941M
Electrodeposited coatings on inch/metric threaded fasteners; thread fit maintained.
ISO 4042
Fastener coating systems, incl. hydrogen-embrittlement relief (baking).
ISO 2081
Electroplated zinc coatings on iron/steel with supplementary treatments.
RoHS / REACH
Trivalent (Cr3+, Cr6-free) passivation for EU export.
Specification data
Cr3+ finish → thickness → salt-spray → ASTM B633 service condition
| Finish | Thickness (µm) | White rust (NSS) | Red rust (NSS) | ASTM B633 SC |
|---|---|---|---|---|
| Clear / blue (Cr3+) | 5–12 | ≥ 72 h | ≥ 120 h | SC1–SC3 |
| Yellow iridescent (Cr3+) | 8–12 | ≥ 120 h | ≥ 240 h | SC2–SC3 |
| Black (Cr3+) | 8–12 | ≥ 96 h | ≥ 144 h | SC2–SC3 |
| + sealer / topcoat | 8–12 | ≥ 240 h | ≥ 480 h | SC3–SC4 |
Values are typical ranges and must be confirmed against the actual part, drawing or governing standard. This page does not replace the customer specification.
Free Engineering Tools
Standards, steel grades and defects for this process
Tested and accepted to
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Frequently asked questions
Do you provide ASTM B633 zinc plating?
Yes. We barrel-plate to ASTM B633 Type II/III, service conditions SC1–SC4 (5–25 µm), with trivalent Cr3+ passivation. The service condition and thickness are confirmed against your drawing.
What salt-spray hours does Cr3+ yellow give?
Yellow iridescent trivalent passivate typically reaches ≥120 hours to white rust and ≥240 hours to red rust in ISO 9227 neutral salt spray; a sealer or topcoat extends this. Actual hours depend on thickness and passivate and are confirmed by test.
Is your zinc plating RoHS/REACH compliant?
Yes. We use trivalent chromium (Cr3+, Cr6-free) passivation, so plated parts are RoHS/REACH compliant and EU-export ready.
Do you bake for hydrogen embrittlement?
Yes. High-strength fasteners — hardness ≥ 320 HV, roughly class 10.9 and above — are hydrogen de-embrittlement baked in-house after plating, per ISO 4042.
What coating thickness can you plate, and do you verify it?
Typically 5–25 µm. Coating thickness is verified by X-ray fluorescence (XRF, ISO 3497) and reported on the lot certificate.
Do you plate threaded fasteners to F1941?
Yes. Electrodeposited coatings on metric and inch threaded fasteners are applied and inspected per ASTM F1941/F1941M, keeping thread fit after plating.
Do you do clear, blue and yellow zinc — and what corrosion hours come with each?
All of them. This is a trivalent (Cr3+) zinc plating line running clear, blue and yellow/iridescent passivation. The colour is not cosmetic — it changes the neutral salt spray hours the finish will reach, so state both the colour and the NSS hours the drawing requires.