Blue Demon ERNI55 X 1/8" X 36" X 1LB Tube nickel 55 cast iron TIG welding rod Used to repair castings, the weld metal is harder than 99. A preheat interpass temperature of 350 degrees F minimum is recommended during welding, without which the weld and heat affected zones could develop cracks. It may be used for repair welds or for joining various types of cast irons