Abstract
The fatigue fracture surface analysis map of a 18 Ni maraging steel (see Fig. 1) is presented for the aging temperature of 482°C and the stress ratio of 0.10. The map consists of the quantitative information obtained from the analysis of fatigue fracture surface and the curve of macroscopic crack growth rate vs. stress intensity factor reported in Ref. 4). It is aimed to estimate the mode of fatigue fracture and the rate and the direction of crack growth from a fracture surface of which a cause is unknown. The effectivity of the map for the above aim is confirmed under other kinds of testing conditions, such as with the prior austenitic grain sizes of 11 μm and 25μm, the aging temperatures of 482°C and 432°C, and the stress ratios of 0.10 and 0.70.
