Zl. Zhang et al., EFFECTS OF CRACK SIZE AND WELD METAL MISMATCH ON THE HAZ CLEAVAGE TOUGHNESS OF WIDE PLATES, Engineering fracture mechanics, 57(6), 1997, pp. 653-664
The heat affect zone (HAZ) is in many cases considered to be the most
critical part of a weldment. In this paper, the effect of crack size a
nd weld metal mismatch on the HAZ cleavage toughness of wide plate spe
cimens with X-groove has been investigated by the J-Q-M theories and a
simple micromechanism for cleavage fracture. Two crack sizes have bee
n studied (a/w = 0.1 and 0.3). In the analyses, the HAZ yield strength
is assumed to be higher than the base metal. For each crack size, wel
d metal local overmatch and local evenmatch with respect to the HAZ ar
e considered. For a given global strain, the results indicate that wel
d metal overmatch and evenmatch yield the same crack tip loading in te
rms of J-integral for a/w = 0.3. For a/w = 0.1, overmatch gives lower
crack tip loading than evenmatch. For a given crack tip loading, weld
metal local evenmatch in general results in less effective crack tip l
oading than the overmatch. Overmatch is detrimental to HAZ toughness,
but this detrimental effect becomes less significant when the crack si
ze decreases. (C) 1997 Elsevier Science Ltd.