304 vs 410

[RWebb]

Is there an inexpensive way to tell 304 from 410 SS fasteners. As both are magnetic due to work hardneing I am having trouble with a simple test. In my application a rusting nut would be a disaster and I have to ensure 304SS.

Thanks R.Webb

 

[redpicker]

A magnet should do it. While your 304 might be slightly magnetic due to cold work, it won't be nearly as magnetic as the 410. You could also hardness test if you wanted quantitative numbers.

rp

 

[unclesyd]

If you are sampling by lot and each lot is still identifiable one way is to heat the samples to white, air cool, then test with a magnet. You will loose the physical properties of the 410 fasteners.


If you have commingled large lots it will be quite difficult to separate the two types of fasteners with a magnet as 304 screws can be very magnetic. We had lots commingled that weren't discernible by hand and had to separated by machine.

 

[RWebb]

Thanks - I did find the magnitism check to be unreliable. I will do the heat check - if it works this is the only spot on the web that has it because I have looked several times at this and never found a good solution - \\Thanks Again!

R. Webb

 

[btrueblood]

You will lose the properties of the (strain hardened) 304 fasteners too, due to annealing. Like unclesyd said, do it only if you have a way of discerning between the two lots, and only do it to samples.

 

[RWebb]

Thanks btrueblood,

Annealing the 304 nut with lock washer I found the nut to be 304 but not the lock washer. Will incorporate this test in receiving prior to releasing to production.

this has been very useful to me and I hope others!

R Webb

 

[stanweld]

For quick sorting of like items and one of the items is of known chemistry (the standard), eddy current testing is a fast and relaible method.

 

[EdStainless]

You can use an electric sorter. there are tables of thermoelectric potentials that you can refer to.

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