L. Bartosiewicz et al., APPLICATION OF A NEW MODEL FOR FATIGUE THRESHOLD IN A STRUCTURAL-STEEL WELDMENT, Engineering fracture mechanics, 45(4), 1993, pp. 463-477
A new model for fatigue threshold has been proposed. The model takes i
nto consideration the influence of material strength. grain size, and
load ratio on fatigue threshold. Fatigue crack growth behavior of a st
ructural steel weldment (ASTM Grade A 514) was investigated to examine
the applicability of this model. The investigation also examined the
influence of welding procedure [submerged arc welding (SMAW) versus me
tal inert gas welding (MIG)] on the resultant microstructure and the n
ear threshold fatigue crack growth behavior of the material in room te
mperature ambient atmosphere. Compact tension specimens were prepared
from ASTM Grade A 514 structural steel weldment in such a way that cra
cks propagated through the heat affected zone (HAZ), base metal and we
ldments. This arrangement permitted the influence of HAZ on fatigue cr
ack growth rate to be determined in both linear and threshold regions
of the Paris curve in room temperature ambient atmosphere. Welding was
accomplished by two different techniques, i.e. SMAW and MIG processes
. The results of the present investigation demonstrated that the near
threshold fatigue crack growth rate was lowest and fatigue threshold w
as highest when the crack propagated through the weldment. The fatigue
threshold values predicted by the model were in good agreement with t
he experimentally determined values. The MIG welding process was found
to be beneficial compared to the SMAW process as far as the fatigue t
hreshold is concerned for weldment.