Stainless Bolts

[Stumble]

Just as a FYI.

Magnetic testing of stainless DOES NOT DETERMINE GRADE.

While the conventional wisdom is that 304 is magnetic, while 316 isn't, this is just wrong. All a magnet can tell you for sure is that the material is either non-cold worked of either grade, or if it was cold worked that it has been thru a stress relief process.

This may be enough of a test for many things, but it is not really all that definitive. The only way to know what you have is a molybendium testing kit which start at around $250.

[Cheechako]

Originally Posted by Stumble

Just as a FYI.

Magnetic testing of stainless DOES NOT DETERMINE GRADE.

While the conventional wisdom is that 304 is magnetic, while 316 isn't, this is just wrong. All a magnet can tell you for sure is that the material is either non-cold worked of either grade, or if it was cold worked that it has been thru a stress relief process.

This may be enough of a test for many things, but it is not really all that definitive. The only way to know what you have is a molybendium testing kit which start at around $250.

yep, especially in shapes like flat bar etc , which normally have a final cold pass in manufacture. The littel bit of Moly in 316 has nothing to do with magetic. It's about grain oreintation and the amount of iron in the mix.

[Lagoon4us]

Originally Posted by Cheechako

yep, especially in shapes like flat bar etc , which normally have a final cold pass in manufacture. The littel bit of Moly in 316 has nothing to do with magetic. It's about grain oreintation and the amount of iron in the mix.

Pick a 304# bolt, washer or nut from your kit, also grab a 316# now place a magnet on them and for some unknown reason only the 304#'s will attract.

As i stated it is a quick test to show what isn't 316#.

We are talking fasteners here.

Cheers.

[Jim Cate]

Originally Posted by Lagoon4us

Pick a 304# bolt, washer or nut from your kit, also grab a 316# now place a magnet on them and for some unknown reason only the 304#'s will attract.

As i stated it is a quick test to show what isn't 316#.

We are talking fasteners here.

Cheers.

The point is this: 304 is more likely to be magnetic due to cold working than 316 is, but it is not ALWAYS magnetic. So, it is possible that using your magnetic discriminator would falsely identify a 304 item (one of the non-magnetic ones that really do exist) as being 316.

Probably not life threatening in teh short term, but a potential problem.

Cheers,

Jim

[Lagoon4us]

Jim it's a hell of a lot cheaper than using a test kit and i've not once been let down by discarding the 304# where i particularly wanted 316# out of the pile of fasteners in the corner of the shed.
The point is 316# is Austenitic and the 394# isn't.

Duralac forever Cheechako....

Cheers.

[Cheechako]

Originally Posted by Lagoon4us

Jim it's a hell of a lot cheaper than using a test kit and i've not once been let down by discarding the 304# where i particularly wanted 316# out of the pile of fasteners in the corner of the shed.
The point is 316# is Austenitic and the 394# isn't.

Duralac forever Cheechako....

Cheers.

Even if the test aint perfect, I suppose it narrows the odds a lot!

The point is 316# is Austenitic and the 394# isn't.
If you meant to say 304... all 300 series is called austenitic SS.

Whats the Duralac story? I know nuttin'.....

[Lagoon4us]

Originally Posted by Cheechako

Even if the test aint perfect, I suppose it narrows the odds a lot!

The point is 316# is Austenitic and the 394# isn't.
If you meant to say 304... all 300 series is called austenitic SS.

Whats the Duralac story? I know nuttin'.....

Have a look at the attached, this is a very good compound, i've never seen a failure with it over 40 years that i've used it from mast building to underwater bolting of prop brackets etc, it's good stuff!

:: Llewellyn Ryland :: Bringing Colour To Life ::

Cheers