In gray cast iron (GCI) castings, it is noted that the machinability of gray cast iron castings varies with the day that the components were cast due to natural aging occuring in the cast components. Similar observations were noted for the natural frequencies of the GCI cast components. Two of the important parameters that influence the natural frequencies of a component (eg. GCI brake disc) are mass and stiffness. Due to the natural aging precipitation that occurs in cast GCI components, can someone explain if this (natural aging precipitation) affects the stiffness or Young's modulus of GCI component? Thank you!
Natural or artificial aging generally used to improve the tensile strength of a material (especially Non-Ferrous). The change in mechanical property have change in stress - stain curve. Obviously stiffness of the material going to change.
In principle, ageing treatment results in diffusion-governed formation of second-phase micro/nano precipitates, which are able to stop dislocation movement under external load higher than a yield stress of the material. Obviously, that these precipitates increase a yield stress. Regarding the stiffness, which is actually Young's modulus, the situation is more complicated. Since a matrix's chemical composition changes throughout precipitates formation due diffusion out of some elements, its Young's modulus may change also.
@Alexander and Gunabalan, I thank you both for your input. My interest is actually to find a way by which the change in the Young's modulus (due to natural aging of GCI) can be mathematically relate to the change in the natural frequency of GCI brake discs. I do know that the natural frequency of GCI disc vary with time after casting of the disc due to natural aging.
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