HANDA. NINGBO

Part group 06 / 05 · Ningbo, China

Stainless bolts,
A2-70 and A4-80 to print.

A2-70 for general assemblies, A4-80 where chloride and salt are in the picture. Grade, class and surface condition follow your print, and the grade is marked on the head instead of being guessed at the port.

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Specification

Stainless Bolts to drawing

Grades
A2 (304) and A4 (316) per ISO 3506-1, classes 50 / 70 / 80 — A2-70 and A4-80 are the usual callouts. 316L, duplex and 1.4529 quoted per drawing.
Sizes
M3 to M24 as standard, M27 and M30 quoted. Length 6 to 300 mm, inch sizes from 1/8 to 1 inch.
Threads
ISO metric coarse and fine, UNC / UNF and BSW. Thread class 6g standard, rolled rather than cut so the grain follows the profile.
Surface
Passivation to ASTM A967 or AMS 2700 when the parts will sit outdoors, plain or polished. No zinc plating on stainless unless you ask: zinc adds nothing to corrosion resistance here.
Inspection
Dimensional and hardness checks per lot, proof load on request, and the mill certificate EN 10204 3.1 for the bar stock. Third-party witness on larger orders.

Every dimension is taken from your drawing or sample. Where this page and your drawing disagree, your drawing wins.

Where these parts go

Applications

Salt air, washdown, chlorides and clean rooms: the places where the grade of stainless, not the price, decides whether the joint is still there next year.

Bolts

Hex, socket, flange, carriage and special-head bolts, class 8.8 to 12.9.

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Screws

Machine, self-tapping, self-drilling, set and security screws to drawing.

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Nuts & Washers

Hex, nyloc and cap nuts; flat, spring and lock washers in four materials.

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Threaded Rods

Full-thread rod, double-end and tap-end studs, cut to length.

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Questions buyers ask

01
Is A4-80 a real class or a sales word?
It is a real class in ISO 3506-1: A4 material at 800 MPa tensile. It is reached by cold working the 316 bar, so the bolt is stronger but a little less ductile than A4-70. The class goes on the inspection sheet and on the head.
02
A2 or A4, which should I specify?
A2 (304) is fine indoors and in ordinary fresh water. Once chlorides appear — salt air, seawater, cleaning chemicals, pool water — specify A4 (316). The price gap is small next to a corrosion claim later.
03
Will stainless bolts gall when the nut is run on?
They can, especially A2 against A2 at speed. Options are a different grade for the nut, a dry-film lubricant, or a coarser thread. We can supply the pair matched so the risk is designed out rather than discovered on site.
04
Do you supply the mill certificate?
Yes: EN 10204 3.1 for the bar stock, plus our own dimensional and hardness record for the lot. 3.2 with a third-party witness is possible on larger orders.
05
Can stainless parts be hot-dip galvanised?
No, and it should not be offered. Galvanising belongs to carbon steel. Stainless is passivated instead, and we can include passivation in the price when the parts are going outdoors.
06
Are the bolts magnetic?
A2 and A4 are austenitic and close to non-magnetic when annealed, but cold heading and thread rolling leave the head and thread slightly magnetic. That is normal and not evidence of the wrong grade.

Next step

Send one drawing.
Get a costed sheet.

Drawing or sample, material, quantity, and the destination port. We reply within one working day with unit price, tooling, lead time and shipping.

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