ժҪ Quenched and tempered (Q&T) steels are prone to hydrogen induced cracking in the HAZ after welding. Austenitic stainless steel (ASS) welding consumables are traditionally used for welding of high hardness Q&T steels as they have higher solubility for hydrogen. The use of stainless steel consumables for a non stainless steel base metal is not economical. In recent years, the developments of low hydrogen ferritic steel (LHF) consumables that contain no hygroscopic compounds are utilized for welding of Q&T steels. The armour grade Q&T steel joints fabricated using LHF filler exhibited superior joint efficiency due to preferential ferrite microstructure in the welds and also they offered required resistance to HIC. However, the combat vehicles used in military operations will be required to operate under a wide range of road conditions ranging from first class to cross country. Structural components in combat vehicles are subjected to dynamic loading with high strain rates during operation. Stress loadings within the vehicle hull of these vehicles are expected to fluctuate considerably and structural cracking especially in welds during the service life of these vehicles can lead to catastrophic failures. Under these conditions fracture behaviour of high strain rate sensitive structural steels can be better understood by dynamic fracture toughness (K1d). Hence, an attempt was made in this paper to study dynamic fracture toughness (K1d) of the armour grade Q&T steel and their welds fabricated using LHF consumables. The dynamic fracture toughness (K1d) of the armour grade Q&T steel and their welds are comparable with each other.
Abstract��Quenched and tempered (Q&T) steels are prone to hydrogen induced cracking in the HAZ after welding. Austenitic stainless steel (ASS) welding consumables are traditionally used for welding of high hardness Q&T steels as they have higher solubility for hydrogen. The use of stainless steel consumables for a non stainless steel base metal is not economical. In recent years, the developments of low hydrogen ferritic steel (LHF) consumables that contain no hygroscopic compounds are utilized for welding of Q&T steels. The armour grade Q&T steel joints fabricated using LHF filler exhibited superior joint efficiency due to preferential ferrite microstructure in the welds and also they offered required resistance to HIC. However, the combat vehicles used in military operations will be required to operate under a wide range of road conditions ranging from first class to cross country. Structural components in combat vehicles are subjected to dynamic loading with high strain rates during operation. Stress loadings within the vehicle hull of these vehicles are expected to fluctuate considerably and structural cracking especially in welds during the service life of these vehicles can lead to catastrophic failures. Under these conditions fracture behaviour of high strain rate sensitive structural steels can be better understood by dynamic fracture toughness (K1d). Hence, an attempt was made in this paper to study dynamic fracture toughness (K1d) of the armour grade Q&T steel and their welds fabricated using LHF consumables. The dynamic fracture toughness (K1d) of the armour grade Q&T steel and their welds are comparable with each other.
2010, Vol. 17 
