Two tests remaining: first, put it in a strong magnetic field and see if it can be temporarily magnetized. If so, you've got ferritic stainless. Next, dunk it in liquid nitrogen & see if a magnet sticks to it when it is really cold. If so, and if you've determined it is not ferritic, you'ved got austenitic stainless.
The more important question, of course, is "whatcha gonna make from it?"