I bought some stainless steel self tapping screws off Amazon.
M3 x 8mm Stainless Steel Cross pan Head Self Tapping Screws.
Within a month they'd gone rusty . The stainless steel tube I tapped them into is rust-free. Country of origin was China.... Anyone know of a better supplier ?
The zinc plated screws I used on another bit of the project were good.
Brian
Did you test them with a magnet to see if they really were stainless ?
Brian Howie explained on 16/07/2022 :
Complain to the seller as a first step.
on 16/07/2022, Andrew supposed :
Not all stainless are none magnetic.
all the stainless screws, threaded bars, washers etc that I have ever bought seem to be non-magnetic though. It's one of the things I always check after purchase when I get home.
Ditto any screws claiming to be 'solid' brass - always test them individually with a magnet.
They stick to a magnet. Some types of SS do.
Brian
They only started rusting after the return period was over - neat eh ? I did complain though.
Brian
I vaguely recall two statements from our lecturer on "Properties of Materials"
1) The world is not made of mild steel 2) Stainless steel is often neither stainless nor steelThis was c1967
I used to take a magnet into B&Q when wanting to buy brass screws, because some numpty on the staff didn't know the difference between brass and brass-coated, and the packets were all muddled up on the same display.
AnthonyL brought next idea :
+1
Although fasteners are usually made from 304 or 316 stainless steel. 316 can be used wherever non-magnetic materials are required and 304 is only very marginally more magnetic.
Even highly resistant stainless steel, like 316, can rust if kept or used in damp conditions with a limited supply of oxygen.
So complain to Amazon - you still have your statutory rights even if the
30 day return window is closed, since the product was obviously not fit for purpose or of a merchantable quality.+1
Indeed. The stainless steel of our cutlery knives occasionally come out of the dishwasher spotted with rust. I guess the blades are a hardenable mix whereas the handles, forks and spoons are not.
>
The stainless steel tube is unblemished. It's been sitting in a damp garage for 25 years. Must check if it's magnetic. No-one's answered my question, but hey this is USENET ;-)
Brian
Any information I have on fastening suppliers is getting on for two decades out of date. What I had then was a place in a large factory unit, filled with anonymous brown boxes, which invariably had what I wanted somewhere. Gone when I last went past that industrial estate.
This place has a good reputation and I think they can do mail order:
304N doesn't rust, we use it extensively at Sellafield.
Also BAPP Industrial Supplies Ltd. I've had stainless M6 machine screws, washers, and nuts, and they've been fine.
Bill
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