抄録
The comparison and relations between fatigue strength with hardness were investigated using eight types of specimens; un-nitrided and ion-nitrided specimens. The fatigue properties of the ultra-low carbon steel sheets (ULCS) have been assessed by evaluating fatigue strength and hardness profile using fully reverse plain bending fatigue testing machine at constant speed of 2000 rpm with the capacity of 49Nm, microhardness tester, an optical microscope and scanning electron microscope (SEM). It was found that ion nitriding improves the fatigue strength by increasing the nitrided layer depth, however the compound layer was found not to have a dominant effect on the fatigue strength. The comparison of test result between un-nitrided and ion-nitrided specimens has shown that the fatigue strength increases up to 37% which could be reached by ion-nitriding process.
