THE EFFECT OF TEMPERATURE ON FATIGUE-CRACK GROWTH IN LIQUID-METAL ENVIRONMENTS

Previous studies of fatigue crack growth in liquid metal environments have shown that at Delta K > Delta K-th crack growth rates are approxi mately one order of magnitude faster than those observed in air. At lo w Delta K values (low fatigue crack growth rates) and/or where the cra ck tip is exposed to the liquid metal for long periods of time, crack tip blunting by dissolution occurs. This decreases the rate of crack g rowth at low Delta K values and results in significantly higher appare nt Delta K-th values. In this paper the effect of temperature on fatig ue crack growth in air and liquid metal environments is investigated u sing standard LEFM testing procedures. It is found that as the tempera ture increases the apparent Delta K-th value increases significantly. These results are explained in terms of the crack tip blunting hypothe sis proposed previously.