In this paper, the effect welding consumables and welding
processes on fatigue crack growth behaviour of armour grade
Q&T steel joints was analysed in detail. From the above illustrations,
the following conclusions are derived:
1) The use of low hydrogen ferritic steel consumables is
found to be beneficial to enhance the fatigue crack growth
resistance of armour grade Q&T steel joints than the joints
fabricated by conventional ASS consumables.
2) The joints fabricated by SMAW process offered superior
fatigue crack growth resistance compared to FCAW
counterparts irrespective of the consumables used.
3) The superior mechanical properties (higher yield strength
and toughness), preferable microstructures (acicular
ferrite) in the weld metal region and beneficial residual
stress field (compressive residual stress) of the weld region
are the reasons for better fatigue crack growth resistance
of the SF joints.
4) From this investigation, it is found that the joints fabricated
using low hydrogen ferritic fillers showed preferable
ferrite microstructure in the weld metal region along with
higher tensile strength, greater weld metal hardness, and
superior fatigue crack growth resistance than other joints.
Hence, it is recommended that low hydrogen ferritic
consumables can also be used for welding armour grade
Q&T steels.