Material selection is one of the most important aspects of successful pattern welding. While I know of many people who have made beautiful steel with recycled materials (band saw blade, banding strap, old files, etc, etc), I personally will use only new materials of known origin and composition. I will occasionally make an exception and use recycled material if the object being recycled has some intrinsic value that it can add to a piece. One of the most moving examples of this I have seen have been knives which included steel from the World Trade Centers as a tribute to those who lost their lives in that tragic event.
While you may think that it’s somehow “cheaper” to use recycled materials, I can assure you that in the long term it generally is not. How would you feel if you spent hours and hours working a billet of steel only to find that it failed to harden in heat treatment? What if it cracks in heat treatment? What if the layers don’t show as brightly as you had hoped? Even under the best of circumstances these things can and do occur. Unless you know FOR SURE what material you are working with, it is a variable that can (and likely will) cause you trouble in the long run.
Good quality steels are cheap in comparison to the time you will spend working them and the value of your finished product. Especially if you plan to sell your work, I implore you to use new, known steels. Why sell your customers something of unknown composition? Are you willing to stand behind something you can’t even identify? I for one am not and so I use only new steels.
Further pages in this section will have more information on material selection, use, properties, and sources.