Stainless Steel Screws.

[landsurfer]

The picture shows the screws holding the handlebars on to my bike. They have been fitted for just over a year and although sold as Stainless Steel you can see the corrosion.
I suspect they are S316 stainless .. so, barely stainless, magnetic and prone to corrosion.
Does anyone know a source of M5 and M4 screws that are of a higher grade of stainless ?????

[reohn2]

Ebay,LBS, https://www.westfieldfasteners.co.uk/ScrewBolt_M.html

[PH]

I used to use a local fixings and ironmongers shop, but they introduced a minimum charge, so have been using Ebay, I'm sure any of them with good feedback would be OK, my last couple of purcheses have been from bolt-world and I've been buying A4 stainless screws
https://www.ebay.co.uk/str/Bolt-World/S ... 3848538010

[reohn2]

I used to use a local fixings and ironmongers shop, but they introduced a minimum charge, so have been using Ebay, I'm sure any of them with good feedback would be OK, my last couple of purcheses have been from bolt-world and I've been buying A4 stainless screws
https://www.ebay.co.uk/str/Bolt-World/S ... 3848538010

I've used Boltworld in the past on Ebay decent company to deal with IME

[alexnharvey]

Check the bolt size carefully, stem bolts are sometimes m7 which I think you will have to order from a specialist bike supplier.

[Eyebrox]

I fill the hex bolt heads with clear grease to prevent rust. It's worked fine over many years.

[WOT]

A4 and 316 are pretty much equivalent grades. Given that the corrosion is only internal it may well be transferred material from the Allen Key used to tighten them, rather than the screw material.

We use this vendor for A4 / 316 screws of various lengths and sizes.

http://www.inox.ie/acatalog/Cap_Screws.html

[landsurfer]

It is structural corrosion, not transfer.
Iron oxide that often occurs with S316 and A4 structures.The screws could well be plated iron.
I have recently removed part of a traction control system from a major UK train fleet that was specified in Stainless Steel.
The label on the cylinder was made of stainless steel !!!
The cylinder was plated iron ... we only found out when the metal recycler did some test drillings to ascertain the material grade.
As a professional Aerospace Engineer corrosion has been part of my working life, now in the Rail industry i see loose specs for S316 appearing all the time.
It corrodes.

[ConRAD]

... and although sold as Stainless Steel ... I suspect they are S316 stainless ...

316SS, or better AISI316, is definitely a good and very popular stainless steel.
AISI316 is definitely stainless and totally amagnetic ... so test your bolts with a magnet, if you note some attraction ... then those bolts are nor 316.

[rmurphy195]

I've had loads of stuff from Namrick, here is theier stainless products
https://www.namrick.co.uk/acatalog/Home_Metric_Stainless_Steel__Grade_A2_and_A4__54.html

[Brucey]

The picture shows the screws holding the handlebars on to my bike. They have been fitted for just over a year and although sold as Stainless Steel you can see the corrosion.
I suspect they are S316 stainless .. so, barely stainless, magnetic and prone to corrosion.
Does anyone know a source of M5 and M4 screws that are of a higher grade of stainless ?????

V3dgHx5PQtu+Bulq%OcEwg.jpg

those are not stainless steel bolts. Therefore any stainless steel bolt would be 'a higher grade of stainless' than those.


The two most common stainless bolt grades are A2 and A4 which roughly correspond with AISI 304 and AISI 316 stainless. A2 contains a small amount of ferrite and is weakly (about 1/10 as much as with a similar 8.8 bolt) arracted to a magnet; it is also stronger and slightly less corrosion resistant than A4. Typically AISI 316 stainless contains between zero and about 5% ferrite and is even less attracted to a magnet.

You can use A4 grade bolts in an a marine environment and they struggle to manifest any visible corrosion. A4 bolts can be made to corrode badly but if the bolts in your picture are A4 bolts and have gone like that then conditions are so severe that there would be practically nothing left of the bike they are attached to.

cheers

[nez]

I have replaced bolts like these with titanium. They're a bit expensive but for definitely no rust applications I love them. Pedal axles, odd nuts and bolts.

[fastpedaller]

A friend once quoted "stainless means one stain less than mild steel "
I've found the stainless set screws/capheads/domeheads sold by Screwfix to be of good quality.

[Brucey]

A friend once quoted "stainless means one stain less than mild steel "
I've found the stainless set screws/capheads/domeheads sold by Screwfix to be of good quality.

choice of A2 and A4 grades from Screwfix

cheers

[Samuel D]

I have used Westfield Fasteners on the recommendation of 531colin of this forum and was pleased with the the whole transaction. Works well for small orders. Plenty of metric bolts.