Development and design of microstructure based coated electrode for ballistic performance of shielded metal arc welded armour steel joints

Joining of high strength armour steel plate developed for lighter armour vehicles using both austenitic and ferritic
type of electrode/filler wire could show inferior ballistic performance of the welds. Combination of hard facing
electrode and softer Austenitic Stainless Steel electrodes, though provided improved ballistic performance,
might not satisfy main design criteria such as strength and toughness due to non-homogeneous microstructure
of weld metal. In order to satisfy improved ballistic performance as well as other design parameters, it is highly
desirable to develop coated electrode which will attribute more homogeneous microstructure in weld metal
similar to high strength armour steel plate.
The present investigation has attempted to obtain martensite, bainite and some amount of retained austenite in
the weld metal by proper design of alloying elements in the coating of SMAW electrode based on metallurgical
index. Three different electrodes attributing different combination of microstructural constituents in armour
steel weld metals exhibited excellent ballistic performance combined with other design criteria such as strength
and toughness at −40°C. However, among the different microstructural constituents lower bainite along with
retained austenite showing maximum toughness both at room temperature and at −40°C could be considered
as most desirable microstructure in armour steel weld metal.