Kbar,I have tried a few different techniques for hardening steel for center punches. The absolute best tip I have is from a member of an international farrier group. Use a steel that has medium to high carbon content. I found an air chipper blade works best. Grind the basic shape you want. Fill a bucket of water to quench hot steel. Using a torch, slowly heat the end of the punch, frequently check to see that the steel will pull the magnet,(the trick is to heat the steel to the point just before it loses its ability to draw the magnetic field). If it gets so hot that the steel will NOT pull the magnet then the process will need to be started from the beginning. Let the steel cool off and start again.The process is described as heating the iron molecules to the point that the carbon molecule is trapped in the center of the cluster of iron molecules. So at the point just before all of the magnetism is lost quickly quench the tool in water to catch the carbon at the hardest point. Now you have hardened steel! Enjoy!...................Barry