Richard,

From a not very good picture* that I took 10(?) years ago. Here is a typical no-oil/no-grease phosphate finish on a U.S. WW II era M-4 bayonet blade. The finish is a crystalline layer on the steel. In the image: the crystals have being flattened and smoothed by the scabbard inserts when the blade was taken out. And put back in. The Germans used an older process but the end result is still basically the same, just not as pronounced.

M-4 phosphate.jpg (77.88 KB, 323 downloads)