Metallurgical characteristics of armour steel welded joints used for combat vehicle construction

Austenitic stainless steel (ASS) and High nickel steel (HNS) welding consumables are being used for welding Q&T steels, as they have higher solubility for hydrogen in austenitic phase, to avoid hydrogen induced cracking (HIC) but they are very expensive. In recent years, the developments of low hydrogen ferritic steel (LHF) consumables that contain no hygroscopic compounds are utilized for welding Q&T steels. Heat affected zone (HAZ) softening is another critical issue during welding of armour grade Q&T steels and it depends on the welding process employed and the weld thermal cycle. In this investigation an attempt has been made to study the influence of welding consumables and welding processes on metallurgical characteristics of armour grade Q&T steel joints by various metallurgical characterization procedures. Shielded metal arc welding (SMAW) and flux cored arc welding (FCAW) processes were used for making welds using ASS, LHF and HNS welding consumables. The joints fabricated by using LHF consumables offered lower degree of HAZ softening and there is no evidence of HIC in the joints fabricated using LHF consumables. Keywords: Armour grade Q&T steel, Heat affected zone softening, Shielded metal arc welding process, Flux cored arc welding process, Austenitic stainless steel, Low hydrogen ferritic steel, High nickel stee