Mt. Kirk et Rh. Dodds, THE INFLUENCE OF WELD STRENGTH MISMATCH ON CRACK-TIP CONSTRAINT IN SINGLE-EDGE NOTCH BEND SPECIMENS, International journal of fracture, 63(4), 1993, pp. 297-316
Previous work by Dodds and Anderson provides a framework to quantify f
inite size and crack depth-effects on cleavage fracture toughness when
failure occurs at deformation levels where J no longer uniquely descr
ibes the state of stresses and strains in the vicinity of the crack ti
p. Size effects on cleavage fracture are quantified by defining a valu
e termed J(SSY) : the J to which an infinite body must be loaded to ac
hieve the same likelihood of cleavage fracture as in a finite body. In
weld metal fracture toughness testing, mismatch between weld metal an
d baseplate strength can alter deformation patterns, which complicate
size and crack depth effects on cleavage fracture toughness. This stud
y demonstrates that there is virtually no effect of +/-20 percent mism
atch on J(SSY) if the distance from the crack tip to the weld/plate in
terface (L(min)) exceeds 5 mm. At higher levels of overmatch (50 to 10
0%), it is no longer possible to parameterize the departure of J(SSY)
for a weldment from that for a homogeneous SE(B) based on L(min) alone
. Weld geometry significantly influences the accuracy with which J(SSY
) for a welded SE(B) can be approximated by J(SSY) for a homogeneous s
pecimen at these extreme overmatch levels.