Factors to weigh
The right finish cuts cost and extends life. Weigh five main factors:
- Environment — indoor, outdoor, humidity, salt, chemicals.
- Hardness/load — do you need the metal itself hard?
- Appearance — what color, glossy or matte.
- Tolerance — fine threads that can’t take a thick coating.
- Budget and volume — high counts need controlled cost per piece.
Match the job to the process
- Corrosion + color, good value → Cr3+ zinc plating (color from passivation).
- Looks, black, preserved thread size → black oxide (+ rust-preventive oil).
- Paint primer / reduced friction → phosphate coating.
- Hardness / clamp load → heat treatment before surface finishing.
- Very high corrosion / marine → stainless or a heavy-duty coating system.
Combining processes
Real jobs often chain steps: harden the bolt first, then Cr3+ zinc-plate for corrosion, then bake out hydrogen on high-hardness parts. The right sequence matters for quality.
V.S. Heat Treatment does it all in one place — hardening, zinc plating, phosphating and testing — so quality is controlled end to end.
FAQ
Harden first or plate first?+
Harden first (set the metal’s properties), then zinc-plate the surface, then bake out hydrogen on high-hardness work.
Not sure what to choose?+
Send a sample or usage spec and our team will recommend a process to fit your budget and real use.
