SPT Study of Spheroidal Graphite Degeneration in Cast Iron Components

In nodular cast iron Mg content is one of the main parameters to take into account. Thanks to the addition of this element, it is possible to generate nucleation points for the formation of nodular graphites which increase the mechanical properties of the material.

The main problem with these alloys is that when they are kept molten for an extended period, the Mg fades away due to oxidation. This generates changes in the shape of the graphites, going from nodular graphite to compact graphite and then to lamellar graphite, depending on the holding time. These microstructural changes directly affect the mechanical properties of the components. 

The main objectives of this study are:

• To determine the detection capabilities of the SPT due to changes in graphite shape
• To acquire the ability to characterize the tensile mechanical properties by SPT for the alloys studied with the lowest possible error.
• To check if there are significant differences when using different correlation methods that have been proposed by different authors during the development of the SPT.

In the study, 2 types of mechanical characterization tests are performed. The traditional tensile test and the SPT test.