Quenched and Tempered (Q&T) steels welded structures that have numerous applications, particularly in the defence industry. However these steels are particularly prone to Hydrogen Assisted Cold Cracking (HACC) and require a highly-skilled welder to fabricate defect-free structures. This is due to the selection of the manual metal arc welding process of shielded metal arc welding (SMAW). The introduction of Modified Pulsed arc mode of depositions; a variation to Pulsed Arc deposition, has advanced deposition rates and can be employed by welders with a greater variation in skill. In this body of work, full strength butt welds are fabricated on 20mm, sections of Q&T AS/NZS 3597 Grade 700 steel under a high level of restraint using Modified Pulse Gas Metal Welding (GMAW-P) and conventional Shielded Metal Arc Welding (SMAW). The study investigates the economic feasibly of the two modes of deposition and the propensity for cracking when welded under high restraint. The study concluded that modified GMAW-P achieved reduction of 63% in the ‘Arc-On' time and an 88% reduction in the total normalised fabrication time. However, due to the increased propensity to lack of fusion type defects, strict controls must be employed in optimising the welding procedure to mediate for such defects if GMAW-P is to provide a techno-economically beneficial alternative to conventional SMAW when welding Q&T steels.

Quench and tempered (Q&T) steels are widely used for a diverse range of applications, particularly in the mining and defence industry, where wear and unconventional loading are common. Furthermore, they are particularly prone to hydrogen assisted cold cracking (HACC), imposing a more careful selection of consumables and requiring a comparably higher welder skill level to fabricate defect-free structures. Therefore, the cost of fabrication of welded structures is higher when the more preferred welding technique of shielded metal arc welding, SMAW, is employed. The introduction of the modified pulsed arc mode of depositions, a variation to pulsed arc deposition, has improved the productivity rates and can be utilised by welders with a greater skill variations. In this study, full-strength butt welds of Q&T steel (AS/NZS 3597 Grade 700), with the thickness of 20 mm, are fabricated under a high level of restraint using both conventional SMAW and modified pulse gas metal welding (GMAW-P). The study investigated the economic feasibility of the two deposition modes and the propensity to cracking for the welded joints under high restraint conditions. Utilising the modified GMAW-P resulted in 63% and 88% reduction in the ‘Arc-On’ time and the total normalised fabrication time, respectively. However, strict controls must be implemented, due to the increased propensity to lack of fusion-type defects, to optimise the welding procedure and mediate for such defects if GMAW-P is to provide a techno-economically beneficial alternative to conventional SMAW when welding Q&T steels.