Stainless steel?

[Rich Z]

Does anyone know of a quick and dirty way to tell if a bolt is stainless steel or regular mild steel? Something non-destructive, of course....

[85vette]

Found this on Wiki....

There are a few different ways to tell the difference between steels. There are a few different types of Stainless steel so some tests work better than others. The 300 series stainless steel contains Chromium and Nickel which makes this steel non-magnetic but the 400 series steel contains just chromium which makes this type magnetic, so first test is if a magnet does not stick to it then it is stainless steel. If a magnet does however stick to it is does not mean that is is high carbon steel, so proceed to the next test. Examine the steel, does it seem to have any rust on it, any red oxidation of the metal which indicated a higher iron content which is found mainly in carbon steels, stainless steel will NOT rust in this way, so if you don't mind putting it to the test try putting a blot of water on it and leaving it over night, if red rust occurs it is carbon steel, if not you have stainless.

[Rich Z]

Well, this probably wouldn't help me much with zinc plated steel. I know stainless bolts LOOK differently than steel or zinc plated, but I'm not sure how reliable of a measure that would be.

And yeah, I have seen stainless steel of both the magnetic and non-magnetic type. It does seem that the magnetic type of stainless steel isn't as STRONGLY magnetic as plain steel, but not sure how reliable that is as an indicator.

[Mannings]

Rich your spot on. We use both in our manufacturing process and the ss has less magnetic properties and also less tensil strength than the carbon steel. The magnet will show some some pull to the ss but will not hang on to the screw, that's really a subjective test. Also the zinc will have a slight color cast usually yellow.