Materials engineer, National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio
Pages: 19 Published: Jan 1975
The strain-cycling fatigue behavior of 10 different structural alloys and metals (two aluminum alloys, two titanium alloys, two stainless steels, a maraging steel, a high-nickel alloy, pure nickel, and pure copper) was investigated in liquid helium, liquid nitrogen, and ambient air at room temperature. Cylindrical hourglass-shaped specimens were loaded in compression and tension about zero mean strain to produce the desired strain ranges. Tensile properties were also obtained for each material and environmental temperature so that they could be used with the Manson-Hirschberg method of universal slopes to predict the fatigue behavior at each temperature.
At high cyclic fatigue lives, fatigue resistance increased with decreasing temperature for all the materials investigated. At low cyclic fatigue lives, fatigue resistance generally decreased with decreasing temperature for the materials investigated. Only for Inconel 718 did the fatigue resistance increase with decreasing temperature over the entire life range investigated. Comparison of experimental fatigue behavior with that predicted by the Manson-Hirschberg method of universal slopes showed that the strain-cycling fatigue behavior of these materials at cryogenic temperatures can be predicted with an accuracy comparable to that achieved in earlier investigations conducted at room temperature. Of the fatigue data obtained at cryogenic temperatures 80 percent were predicted within a life factor of 3.
storage tanks, fatigue (materials), strain-cycling fatigue, low cycle fatigue, cryogenics, mechanical properties, fatigue life prediction, helium, nitrogen, liquefied gases, fatigue tests
Paper ID: STP29170S