Nickel cored electrode with a special coating for welding grey and malleable cast iron. It has a “pulsating” way of welding. There is alternately a phase where the arc only creates “heat” without deposit (oil and grease are burned out of the base metal during forward motion) and a phase (backwards motion) where a droplet on the cast iron is projected. In this last phase, the slag is pushed backwards and a very large area around the molten pool stays visible, permitting easy control of porosity on contaminated or oil soaked cast iron. Due to the pulsating properties (controlled heat input) and the possibility to use the negative pole for the first pass (slower cooling rate and thus less hardening of the heat affected zone), a soft, machinable and dense deposit without undercutting is easily obtained.
Recommended for welding cast iron that has to be leak-tight and machinable, such as cracked motor blocks, pump housings, gear wheels, rebuilding the bed of a lathe, valve seats.
Hardness: 130 - 160 HB
For the first pass on cast iron, Lastek 40E is welded on the negative pole with a weaving technique(weaving forwards and backwards in the direction of travel)
Following passes can be welded on the positive pole to increase travel speed.
Peen the deposit after every pass to reduce stress build-up.