Effects of Strain Aging in the Unloading Compliance Test
SourceThe behaviors of two heats of SA 515 Grade 70 in the unloading compliance J test were compared. Tensile properties were measured for both heats of material; one heat was found to be susceptible to dynamic strain aging. This heat also exhibited a steeper drop in the slope of the JI-R curve with increasing temperature, and serrated flow during the high-temperature J tests. The magnitude of the serrations varied during each test and with changes in loading displacement rate. Comparison with data from other carbon steels and weld metals showed that a large JIc drop with increasing temperature was associated with a large drop in ductility. J tests of strain-aging susceptible materials also showed a marked decrease in load drop from relaxation and peaks in load upon reloading at temperatures at the lower end of the temperature range of dynamic strain aging.