Ej. Rao et al., EFFECT OF WELDING PROCESS ON FATIGUE-CRACK GROWTH-BEHAVIOR OF AUSTENITIC STAINLESS-STEEL WELDS IN A LOW-ALLOY (Q-AND-T) STEEL, Theoretical and applied fracture mechanics, 27(2), 1997, pp. 141-148
Fatigue crack growth behaviour from a lack of penetration (LOP) defect
in austenitic stainless steel weld metals of cruciform joints made of
a low alloy high strength (Q&T) steel has been studied to understand
the effect of two welding processes, namely, shielded metal are weldin
g (SMAW) and flux cored are welding (FCAW). Fatigue crack growth studi
es were carried out at a stress ratio of R=0 and a frequency of 90 to
110 Hz in a resonant testing equipment (Rumul, Model:8601). Crack grow
th rates were relatively lower in the weld metal obtained by flux core
d are welding process. Microstructural features observed revealed mark
ed difference in the morphology of delta ferrite for the welded joints
obtained from the above two welding processes. Long streaks of delta
ferrite in austenite matrix were found in case of SMAW-weld metal whic
h seem to have lowered the resistance to the fatigue crack propagation
. A discontinuous network of delta ferrite found in austenite matrix i
n the case of FCAW-weld metal seems to have contributed to slower prop
agation of fatigue crack. Fractographic features also substantiate the
observed trends in the fatigue crack growth behaviour.