Have you annealed steel or cast iron? Well let me tell you the process. You heat the metal in a furnace till it is red hot. You stick a pole with a swinging magnet on the end to the iron, if it is attracted to the metal you heat it up some more, if it is not attracted to the metal then that means it is above the magnetic line of 1450 degrees F. You prepare a box full of gypsum and lime and quickly place the metal in this box, add more gypsum, and let cool for a day or too. To harden metal you do the same thing except you quench the metal in water or oil. Then you temper it by heating it to 600 degrees and let it air cool. You will temper it several times. Our engines will be sitting in a pool of molten aluminum and brass if we heat the metal up enough to anneal the iron piston or steel sleeve. You wouldn't want to anneal it in any event, the steel sleeve and piston would become very soft, the steel may be almost as soft ar copper. It wouldn't last very long.