Investigating that how the fatigue strength of high manganese cast steel is influenced by grain size, decarburization and embrittlement of carbide precipitation and also the effect of shotpeening there obtained the underwritten results.
(1) The grain size dependancy of fatigue limit is relatively small comparing with that of structural steels, and the coarser it becomes the lower the fatigue limit with the rate of 0.5kg/mm2/grain size number.
(2) The reduction in the fatigue strength due to decarburization is smaller than that of structural steels. This is because that the micro structure of outer layer changes into hard martensite from austenite due to decarburization.
(3) The temper brittleness makes the fatigue limit raised as hardening follows after precipitation.
(4) The shotpeening is effective for improving the fatigue strength of various surface finish and it makes the fatigue limit raised up from 6 to 25%.
