Posted by Joe Lorenzino on Monday, February 10, 2003 at 9:15PM :
In Reply to: What is best method to weld cast iron? posted by DG on Monday, February 10, 2003 at 8:11PM :
Step 1: what type of metal is it?? When repairing "unknown materials" at work, we ALWAYS do a spark test to determine the metal type (iron, steel, etc) and the carbon content so that we can choose the most suitable repair method. Check out some of the blacksmithing sites on the web for a guide to spark testing. (anvilfire.com)
(You can't fix it properly if you don't know what it is) Take the piece to a grinder, touch it to the wheel, and watch the sparks. Yellow with glitter: cast steel - preheat and weld as usual. Dull orange: cast iron - use nickel rod or a torch-on process. All of the methods mentioned so far are suitable, but if you are going to arc weld with a nickel rod, there is a lot less micro cracking along side the weld if the temp can be kept OVER 900 for the entire process. Longer welds (2" or so)can be done because the base metal does not quench the weld area. Peening between passes is HIGHLY recomended, and the slow cooling helps as well. At work, we have a 45gal. drum 1/2 full of vermiculite that we bury hot parts in to cool them slowly. Using brass rod applied with a torch is also a good choice on cast iron. In any case, make sure the area is Clean, and that all traces of the cutting slag are removed by grinding before any repair is done. good luck Joe L.