It could be done, but most likely you wouldn't like the result. First, you have warpage. Even the pro manufacturers with all the proper heat treating gear and computer controlled processes still toss a certain percentage due to excessive warpage. The guys with a torch and a bucket of water or oil have a much higher rate. Also, doing different sections at a time would increase the likelihood as the cold areas wouldn't expand as much as the hot, imparting stresses to the metal.
Second, the heating process would not impart an even hardness. The section getting red hot would bleed heat over into the previously heated section, changing it's temper. Essentially you would have three heat treated sections separated by bands of annealed steel.
Second, the heating process would not impart an even hardness. The section getting red hot would bleed heat over into the previously heated section, changing it's temper. Essentially you would have three heat treated sections separated by bands of annealed steel.
