Pengaruh Komposisi 2.9% dan 3.8% Si terhadap Kekuatan Lelah Besi Cor Kelabu

The addition of Silic on (Si) on the gray cast iron can initiate graphite dispersion where the graphite becomes smaller and more evenly distributed. This study investigated the effect of Si concentration of 2.9% and 3.8%  on the fatigue strength of the gray cast iron. The Si  was added by the casting process with the open ladle method. The specimens were manufactured by  following the  ASTM E-466 . Several tests such as tensile test,  Brinell  hardness test, and microstructure observation were conducted prior  to the fatigue testing. The results showed that the  Si concentration of 3.8 % tended to increase the tensile strength up to 1.3%, the hardness up to 7.6%, and fatigue limit up to 10%. Moreover, the fatigue fractured specimen of 3.8% Si showed the combination of type A and type B graphite where graphite is smaller and more evenly distributed. In addition by applying the logistic equation, the fatigue strength  can be  predicted well.