Abstract
Amidst the growing needs to apply CV graphite cast iron to large castings, there have only been a few reports on the fatigue strength characteristics of CV graphite cast iron. Moreover, large castings are prone to producing chunky graphite and inhibiting mechanical properties.
In this study, FCV test castings capable of simulating the slow cooling rate of large castings with 150mm thickness were produced by adding rare earth element, and plane bending fatigue tests were conducted to investigate the influence of wall thickness on fatigue strength.
It was confirmed that the number of graphite grains decreased and the graphite particle size increased with increasing mass in each specimen. In addition, in the plane bending fatigue test, the fatigue strength of each specimen showed a similar value. These test results confirmed the weak correlation between the wall thickness and fatigue strength in the range of the experimental conditions. Moreover, in the observation of the crack growth behavior, an initial crack was generated at the end of the non-spheroidal graphite in the initial stage. With the increase of the number of repetitions, the crack propagated in the form of sewing the graphite while repeating the connection and coalescence with the leading crack generated from other graphite etc.
