There is nothing wrong with the steel. However, there is a LOT of bad advice in that article. Beating on old leaf springs, COLD, is asking for trouble, and mostly just a lot of unnecessary work for you (and really bad for your hearing). The claim that no small outfit can do as well as a big auto corporation for heat treating is simply nonsense. You can do it that way, but it is by no means the best way.

I have no doubt that the author is sincere, but he is also confused about a great many things regarding steel and metallurgy.

I do make a living, making high performance swords, btw.

Nothing personal, just be aware that it is not the best information out there concerning the making of a sword. I highly recommend www.dfoggknives.com and www.britishblades.com/home/ as good sources on the web.