A2 stainless screws - 2nd opinion please

[Steve_N]

Just received a box of supposedly 'A2 304 grade stainless steel' screws which look and feel like non-stainless zinc-plated.

Dipping a cycle computer wheel magnet into the box has the result pictured.
Is that proof enough that they aren't A2, before I go on the war path to the supplier?

 

[Talulah]

A2 are partially magnetic. If it takes anything more than a very light pull to seperate them then they are not A2.
Give em hell.

 

[Steve_N]

Thanks.
A single screw will jump up onto the magnet from 10mm away and takes a strong pull to detach it.
I've tried with some known A2 ones that I have and I can just about persaud one to stick to the magnet..

 

[macd]

You've been robbed. Apart from magnetism, if they are plated, the colour should give them away.

 

[prv]

I would go more by colour than magnetism. Unfortunately your picture is a bit over-exposed, but from what I can see they look zinc-y to me.

I would assume a packing mistake (warehouse yoof took the wrong box off the shelf) before a deliberate attempt to defraud, as the difference is so obvious.

Pete

 

[vyv_cox]

Definitely not A2. Low grade 304 stainless steel can have a small ferrite content that makes it very slightly magnetic but nowhere near as much as shown in your photo. But as macd says it is quite easy to tell zinc plate from stainless steel by the colour. Compare them with a piece of known SS.

 

[Steve_N]

Thanks all and, yes, they fail the colour test also (known A2 on the left):

I'm confident that it's a genuine mistake and that it'll all get sorted.

 

[Chris_Robb]

If you have a problem, go with these guys.

http://www.accuscrews.co.uk/

Are these internal use screws or external? If so what about using A4

 

[nigelmercier]

I'd say they are galvanised. Hydrochloric Acid will soon tell you.

Are you going to name the supplier?

 

[Steve_N]

For internal use, attaching battens.

Dropped one in some brick cleaner - fizzed nicely and came up grey steel.

No naming just yet - negotiating..

 

[MM5AHO]

They're very unlikely to be galvanized. Its just not very practical to galvanize such small items, though not impossible. Don't think anyone in UK does high temperature centrifuge galvanizing any more.

Much more likely to be electroplated zinc.

Hydrochloric acid won't tell if they're galvanized. If they were electroplated you'd get the same reaction, same for sheradized (but they're not that either), and various other electroplated metals.

 

[JClarkes]

They look zinc plated to me.
If you need A4 No.6 or No.8 I have plenty.

 

[GrahamM376]

Just received a box of supposedly 'A2 304 grade stainless steel' screws which look and feel like non-stainless zinc-plated.

Dipping a cycle computer wheel magnet into the box has the result pictured.
Is that proof enough that they aren't A2, before I go on the war path to the supplier?

If in salt water shouldn't you be using A4?

 

[nigelmercier]

Hydrochloric acid won't tell if they're galvanized. If they were electroplated you'd get the same reaction...

Doesn't matter. The question is: are they A2 stainless, or zinc coated. The latter has been proven with the acid.