A Fatigue Fracture Surface-analysis Map of the 18Ni Maraging Steel

Abstract

A fatigue fracture surface-analysis map of 18Ni maraging steel (see Fig. 1) is proposed using the condition of the aging temperature of 482°C and the stress ratio of 0.1, which consists of the quantitative information obtained from the analysis of fatigue fracture surface and the curve of macroscopic crack growth rate versus stress intensity factor. The map intends to estimate the mode of fatigue fracture, the rate and the direction of crack growth, etc. from a fracture surface of which the cause is unkown. The effectivity of the map for the above aim is confirmed using the other four kinds of testing conditions, namely the prior austenitic grain sizes are 11 μm and 25 μm, the aging temperatures are 482°C and 432°C, and the stress ratios are 0.1 and 0.7.