Unknown stainless steel

[sorveltaja]

How to identify an unknown ss grade?

Characteristics:
Slightly greyer than 304, for example.
Machinability as good, as on mild steel.
When machining, it gives faint smell of sulphur.

I luckily got some pieces from scrap yard. At first I thought it was mild steel, but closer inspection revealed, that there wasn't any rust layers, that I expected.

Any info is welcome. It sure is a material, that I'd like to have more. Hopefully it doesn't turn out to be too expensive for me .

[No1_sonuk]

Is it magnetic?
Some are, some aren't so much.

[sorveltaja]

Yes, quick testing showed that it has approximately same level of magnetism as mild steel.