Docentföreläsning - Jessica Elfsberg

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Titel: Cast Iron Parts in Heavy Duty Vehicles

Abstract:

Heavy Duty Vehicles are vehicles performing some kind of heavy work. Often by transporting goods or transporting people. The vehicles from Scania CV AB have cast iron parts operating under very different conditions. The three cast iron types LGI (Lamellar Graphite Iron), CGI (Compacted Graphite Iron) and SGI (Spheroidal Graphite Iron) are all used by Scania since they are suitable for different applications. Some parts are exposed to high, cyclic, temperatures, other may in some climates experience very low temperatures. Furthermore there are for example high static loads, cyclic loads causing fatigue and different corrosive media to consider. Material properties of interest are not only strength but also thermal conductivity, mechanical damping and oxidation resistance. Material properties are generally  controlled by microstructural features as for example graphite shape and matrix structure. The microstructure is controlled by the chemical composition and by the manufacturing process. However, the properties are also limited by the presence of defects. It is not possible to cast 100% defect free parts, thus the defects need to be considered during the design process.

The development of cast iron parts at Scania focus not only on the actual material properties, but also on the possibility to model their behavior for optimizing the design and estimating their life length at different conditions. Models and tools are developed internally as well as in cooperation with academic partners. Two examples are the correlation between strength and microstructure for two cast iron types (LGI and CGI) and a diagram describing the static strength as a function of defect size in SGI.