[JWL]

Welding cast iron can be an interesting challenge. A restrained joint condition, such as the middle, side of an engine block, can be the more difficult to deal with. There are two basic procedures commonly used. The first is what can be termed "cold welding". This involves using a very ductile stick electrode with absolute minimum heat applied and followed with immediate "peening". The weld actually looks like a series of very short spots, each of which have received serious peening. There is plenty of cooling time allowed between the application of each weld "spot" and the temperature of the weld area is never allowed to become uncomfortable to the bare hand resting on it. It is best to have 2 jobs going on at the same time so you can weld a "spot", peen for a minute, go to the second job for 30 minutes, return for another round of spot and peen, etc. etc. A highly restrained joint can survive best if "buttered" all around with your ductile filler rod before attempting completion or closure of the crack or hole. In other words, the final weld spots should not join 2 sides of cast iron, but rather, couple 2 sides of filler rod.

The second method for welding cast iron involves using a large furnace where the block is allowed to "soak" so the core termperature is maintained at a high level. For spray welding the core temperature should not drop below 600 degrees. This means it is sometimes necessary to either return a partially welded item to the furnace or apply some of the welding while the part is in the furnace. As you might guess there can be some discomfort for the operator. Some procedures require 1000 degrees, or more, to safely weld cast iron. The welding is followed by a strict cool-down procedure which can take 2 or more days.

Welding of non-restrained joints in cast iron can be as simple as welding steel. But, any restrained joint condition can set off a series of unpleasant happenings when welding is done.