VAMAS Technical Working Area 19 on High Temperature Fracture of Brittle Mat
erials has developed several new recommendations for determining and analys
ing the creep crack extension behaviour of creep-brittle materials. These r
ecommendations, most of which are also useful for creep-ductile materials,
include: machining narrow starter notches for brittle materials; definition
of creep crack initiation; definition of creep toughness; recommendations
for conducting creep crack growth tests under the conditions of constant di
splacement rates or stepwise increments in displacements and/or displacemen
t rates, in addition to the usual constant force method; additional paramet
ers for correlating the creep crack extension rate, such as stress intensit
y factor, K, C-t parameter, Q* parameter, and rate of delta(5) type CTOD, (
delta)over dot(5); and criteria for the various correlation parameters. The
se recommendations are presented in a form which should aid development of
national and international standardization of creep crack extension test me
thods, (C) 1998 Published by Elsevier Science Ltd. All rights reserved.