Abstract
In this study, CT specimens were prepared from ASTM A516 Gr. 65 which was used for pressure vessel plates for moderate and lower temperature service. Fatigue crack growth test was carried out in the environment of low temperature of $10^{circ}C, -10^{circ}C, -30${circ}C\;and\;-50^{circ}C$ and in the range of stress ratio of R=0.05 and 0.3 by means of opening mode displacement. Based on these test results, the characteristics from temperature and stress ration were shown as follows. 1) As the stress ratio, R increased da/dN and ${Delta}K$ of 2nd stage gradually decreased. And as R decreased, the effect of temperature became greater and greater. 2) As the temperature descended, da/dN decreased on a certain ${Delta}K$, and ${Delta}K$ did in a same da/dN. And the stress ratio, R exerted greater influence at the lower temperature. 3) The fatigue crack growth constant, m increased at $10^{circ}C$ and $-10^{circ}C$, snd decreased at $-30^{circ}C$ and $-50^{circ}C$ following the increment of stress ratio R. And m increased along with the reduction of temperature greatly decreased at $-30^{circ}C$ to come close to two(2).
