Cast iron can be welded , but ! those things mentioned by others here must be followed . The heating /cooling cannot be hap hazard , Other than nhe heating cooling cycles , cleaning is very important . Cast iron welding filler rods can be made from scrap pcs. of parts of other broken cast items . If the scraps are from the same foundry as the item(s) to be repaired , this is a bonus toward success . One of the biggest problems with cast is it has a tendancy to retain dirt grease and etc. even after cleaning and grinding . I,ve had some items that were great to weld , but mostly NOT! A person needs to practice on much scrap before attempting this type of weld. The success rate for this type of weld is quite low on old cast . I would suggest using a braze instead of a weld .