Abstract: An experiment was carried out on the high frequency fatigue testing machine PX-100 and with the method of progressively increasing/decreasing stress to determine the fatigue limit of wheel spoke steel S500LF on the condition that the vibration frequency was 100~120Hz and the tensile-compressive stress was symmetrical. The fatigue limit was 291MPa by the mathematical statistical analysis. When this value was used as an estimator of the maternal 50% survival rate， the relative error was no more than ±5% with a confidence level of 95%. The fatigue life at different stress levels was measured by the multi-sample method according to the measured fatigue limit. Based on this， the S-N relation curve was drawn and the S-N curve equation was regressed. Besides， the fracture of the samples was analyzed theoretically， and the result shows the good toughness of the test steel.

Key words: spoke steel, fatigue limit, S-N curve, fatigue fracture