What automotive work requires
- Corrosion to a stated salt-spray rating, verified by test.
- Cr6-free (Cr3+) coatings per RoHS/ELV.
- Traceable quality documents (certificate, lot traceability).
- Lot-to-lot consistency, especially across high-volume fasteners.
Fastener-specific risks
High-strength screws/bolts (class 10.9/12.9) risk hydrogen embrittlement after electroplating, so they need a hydrogen-relief bake.
Coating thickness must be controlled so threads do not bind or torque values drift.
How we help
Cr3+ zinc, phosphate and hardening, plus a hydrogen-relief bake for high-strength work.
Hardness/thickness/salt-spray testing with documents attached per lot as required.
FAQ
Does automotive need Cr3+?+
Usually yes, per RoHS/ELV—we plate with a Cr6-free system and provide documentation.
Do you bake high-strength bolts?+
Yes—a post-plate hydrogen-relief bake lowers the embrittlement risk on high-strength work.
Can you issue per-lot quality docs?+
Yes—test certificates and lot traceability as the customer requires.
Free Engineering Tools
- Hardness Converter HRC ↔ HV ↔ HB
- Which Steel Grades Harden — and How Far
- Fastener Weight: pcs ↔ kg
- Finishing Specification Builder for Purchasing and QC
- Salt Spray Test Plan Builder
- Coating thickness → thread fit (GO/NO-GO)
- Hydrogen Embrittlement — is baking required?
- Bolt Tightening Torque & Proof Load
- Thread Engagement Length
- Bolt Size Estimator (from load)
- Bolt Property Class — Mechanical Properties (ISO 898-1)
What this article covers at our plant
Related comparison guides
- Zinc plating vs Dacromet / zinc flakeZinc plating vs Dacromet: which coating for screws and bolts?
- Black oxide vs PhosphateBlack oxide vs phosphate: which finish for screws, nuts and bolts?
- Electroplated zinc vs Hot-dip galvanizingZinc plating vs hot-dip galvanizing: which one does your fastener need?
- Zinc plating vs Zinc-nickelZinc plating vs zinc-nickel: when is the upgrade worth paying for?
- Barrel plating vs Rack platingBarrel plating vs rack plating: how small fasteners are actually plated
- Zinc phosphate vs Manganese phosphateZinc phosphate vs manganese phosphate: match the coating to the job it does
Technical content review
Reviewed by the V.S. Heat Treatment QA and production team—heat-treatment and finishing operations since 1994 under an ISO 9001:2015 quality system.
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