材料期刊网

Quenched and Tempered (Q&T) steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking (HIC) and softening in the heat affected zone (HAZ) after welding. The use of austenitic stainless steel (ASS) consumables to weld the above steel was the only available remedy to avoid HIC because of higher solubility for hydrogen in austenitic phase. Recent studies revealed that low hydrogen ferritic (LHF) steel consumables can also be used to weld Q&T steels, which can give very low hydrogen levels in the weld deposits and required resistance against cold cracking. Hence, in this investigation an attempt has been made to study the performance of armour grade Q&T steel joints fabricated by flux cored arc welding with LHF steel consumables. Two different consumables namely (i) austenitic stainless steel and (ii) low hydrogen ferritic steel have been used to fabricate the joints by flux cored arc welding (FCAW) process. The joints fabricated by LHF consumable exhibited superior transverse tensile properties due to the presence of ferrite microstructure in weld metal. The joints fabricated by ASS consumable showed higher impact toughness due to the presence of austenitic phase in weld metal microstructure. The HAZ softening in coarse grain heat affected zone (CGHAZ) is less in the joints fabricated using LHF consumable due to the lower heat input involved during fabrication compared to
the joints fabricated using ASS consumables.