NUCLEATION AND GROWTH OF CREEP VOIDS IN CIRCUMFERENTIALLY NOTCHED SPECIMENS

Several creep damage tests of pure aluminum were carried out using cir cumferentially notched bars, which can easily produce multiaxial state of stress near net section. The surface of notch root and longitudina l section with central axis were inspected to observe the growth of cr eep voids and cracks by means of scanning electron microscopy and opti cal microscopy. Experimental results show that: the maximum length of the largest creep void/crack on the notch surface can be expressed as an exponential function of lifetime ratio. This will help to predict r esidual lifetime of components with these notches. However, a great ca re is required not to miss the maximum creep defect, because only a pa rt of creep voids and cracks appears on the surface of notch root and most of the creep defects lie inside the notch root.