Fatigue-crack propagation and residual static-strength data on PH15-7Mo (TH 1050) stainless steel are presented in this thesis. In addition, the capability of McEvily and Illg's crack-growth analysis and Kuhn and Figge's residual strength analysis to correlate the test data has been investigated. Axial-load fatigue-crack propagation (at R = 0 and -1) and residual static-strength tests were conducted, on 2-inch-wide sheet specimens made of PH15-7Mo (TH 1050) stainless steel. Analysis of the data showed that as individual analysis methods both analyses satisfactorily correlated the majority of the test data. However, the material constants derived in the two analyses differed significantly. This difference was attributed to the different amounts of work-hardening which occurs in the material prior to failure in the two cases. The effects of the different stress ratios on fatigue-crack growth were studied. In addition, the capability of the residual-strength analysis to predict the effects of changing buckling restraint in the vicinity of the crack.and of changing specimen width were investigated. / Master of Science

Industry is constantly searching for improved materials for use in highly demanding applications. The materials chosen must withstand a wide range of temperatures and extended exposure in aggressive environments, including hydrogen gas. Because of the risk of catastrophe if brittle failure occurs, careful material selection is imperative. Austenitic stainless steels may be a likely choice for hydrogen service because their behavior in high pressure hydrogen ranges from no apparent damage to relevant, but generally small ductility loss (13). Because of this Variation in behavior, a single category cannot be established to encompass all austenitic steels and studies must be performed on each type of steel to determine its behavior under specific circumstances. Two steels being currently under consideration for use in hydrogen are Armco 21-6-9 and Tenelon, both are fully austenitic stainless steels which may be used over a wide range of temperatures, including service at liquid nitrogen temperature. / Master of Science / incomplete_metadata