I think what you're looking for is an acid, check the PH of bleach. You may be trying to remove steel in this process, not convert it to something else. If you want something more agressive, you could try plain old pool acid.

I've done it a few time over the years, but mainly on garage sale finds. I think you can get some more use out of a rasp or file, but careful with metal files intended for a good finish.