Identifying stainless steels.

[EricB]

Is there some method of testing that a hobbiest can perform to verify a piece of stock is stainless? I purchased a length of what was called 303 on ebay and what arrived was rusty and magnetic.

Thanks,
Eric

 

[GeneT45]

303 is somewhat magnetic, though less so than a piece of mild steel. I haven't had any rust though.

GsT

 

[Martin W]

You may be able to take it to a local scrap dealer. They would have the ability to test it for you.
Martin

 

[RandyM]

Is there some method of testing that a hobbiest can perform to verify a piece of stock is stainless? I purchased a length of what was called 303 on ebay and what arrived was rusty and magnetic.

Thanks,
Eric

If you want non-magnetic and true corrosion resistance, then use 316.

 

[Ischgl99]

The 303 I have is slightly magnetic, if you press a magnet against it, it will stick, but it won't draw it in like a carbon steel will. Stainless steel is not corrosion proof, it can rust under the right conditions, especially in a corrosive environment. Do you have a picture of the rusty piece?

 

[benmychree]

I have made a ton of 303 parts, never saw any rusting, either in the weather or in slightly acidic conditions (wine).

 

[benmychree]

A test with 303 would be machinability; it is not much different than soft steel, in fact nicer to machine than soft steel.

 

[ChazzC]

303 will get surface rust if you use tools (wire wheels and even hand tools) that are made from (or previously used on) carbon steel have - microscopic amounts of carbon steel will be transferred to the 303 surface. This is why contractors who work in the Food, Pharmaceutical and Nuclear industries (and some others) have separate job boxes labeled "Stainless Only."

 

[Ischgl99]

I have made a ton of 303 parts, never saw any rusting, either in the weather or in slightly acidic conditions (wine).

I worked in the wastewater industry, stainless didn’t rust like carbon steel, but it wasn’t uncommon to see some surface rusting on parts in the process areas.

 

[ChazzC]

Yes, usually just surface rust, not pitting. However, while this is OK in waste water treatment and other industries where you are looking for materials not to "fade away," in Food, etc., even light surface rust is a problem: can't fully clean/sanitize (and inspectors like to see shiny things).