It has been investigated if the lower bound of a fracture toughness trend b
and for the weld metal database of a nuclear pressure vessel is being envel
oped by a 5% master curve and if the reference temperature T-0 of the maste
r curve is correlated with other reference temperatures used to characteriz
e the fracture toughness. The results show a correct description of the low
er bound of the data trend by a 5% master curve for the major part of the t
emperature regime of interest; for the upper transition regime the approach
appears to be overly conservative. The master curve T-0 derived from small
specimen tests gives a lower bound adjustment of the ASME K-Ic curve. (C)
1999 Elsevier Science S.A. All rights reserved.