炭素鋼의 疲勞限度의 豫測을 위한 評價因子 = Evaluation factor on Prediction of Fatigue Limit in Carbon Steel

다국어 초록 (Multilingual Abstract)

The fatigue strength of structural steels containing small defect or inclusion are so complicated that the prediction influence of the defect or inclusion is very difficult. This study simplifies these factors to evaluate the influence use projected area of the defect or inclusion in low and medium carbon steels.
The investigation is carried out by a quantitative evaluation relationship between fatigue limit and √αγeα. We study this issue using SM15C and SM35C materials.
(1) In the experiment, The critical crack length of _EFM is coincide to the intrinsic crack length of Haddad method. (2) Only defects and inclusion larger than a critical size have harmful effects on the fatigue strength of metals. The critical size is concerned with the length ιc of small non-propagating cracks which are observed at the fatigue limit of un-notched specimens. (3) The lower limit σwι of scatters of fatigue strength can be predicted by Murakami and colleagues method, in which the square root of the projected area (√αγeα) of inclusions are the crucial influential parameters. The value of σwι depends on the maximum inclusion(√αγeαmax) which is expected to be contained in specimens or machine components.