Fatigue strength of large steel screw threads under axial loading.
Abstract:Constant amplitude axially loaded fatigue test data for about 160 solid steel bolts and studs with nominal thread diameter equal to or greater than 1.5 in (38 mm) are presented in the form of S-N curves in which the alternating stress is non-dimensionalised by the tensile strength of the material. Data are given for threads that were cut, ground or rolled for both Whitworth and Unified forms. Mean endurance curves and upper and lower limit of scatter curves within which 90 per cent of the data fall are shown. The data indicate that threads that are fully heat treated before form or root rolling have the best fatigue endurance compared to threads that are cut and ground from fully heat treated materials.
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