Weldability of Jackal Steel

I had talked about armour steel welding.While we were doing literature survey we found that all western countries were using stainless steel electrodes where as Russians were welding with carbon and low alloy steel electrodes.These are classified as ferritic electrode The argument given by the western countries were since armour steels are susceptible for hydrogen induced cracking they decided to use austenitic electrodes for welding.

This needs to be explained. While welding armour steel slightest amount of hydrogen in the weld causes under bead cracking. This hydrogen come from various sources, such as, improperly dried electrodes, rust and grime on the plate, paint marks or condensed water etc.When the plate is welded with a ferritic electrode the hydrogen is first absorbed in the weld metal and as the weld metal cools hydrogen migrates to heat affected zone which contains martensite and in course of time a crack develops. The hydrogen induced cracks take at least 72 hours to develop.

The solubility of hydrogen in the austenitic weld metal is high and is not liberated to heat affected zone after cooling as in the case of ferritic weld metal. Since the migration of hydrogen to heat affected zone is absent the chances of hydrogen induced cracking when armour steel is welded with austenitic stainless steel electrodes are less.

The question arises then why Russians weld with ferritic electrode. They are not dumb. The Russians have a valid argument.

In the manufacture of steel Russians follow a technology of steel making which contains very less hydrogen. More over all their armored vehicles are welded by MIG welding which is known to contain less Hydrogen. More over they used to manufacture large number of armoured vehicles for supplying to their allies almost free. Hence they used ferritic weld metal which is cheaper.

We put all these facts before DMRL and DMRL suggested that we should use austenitic electrodes. Hence we did all our experiments with austenitic elrctrodes,