The thermal conductivity of Compacted Graphite Iron (CGI) and spheroidal graphite iron (SGI) was established in the temperature range from room temperature up to 500 °C using the experimental thermal diffusivity, density and specific heat values. The influence of nodularity, graphite amount, silicon content and temperature on the thermal conductivity of fully ferritic high-silicon cast irons was investigated. It was found that the CGI materials showed higher thermal conductivity than the SGI materials. The thermal conductivity tended to increase with increasing temperature until it reached a maximum followed by a subsequent decrease as temperature was increased up to 500 °C. Conventional models were applied to estimate thermal conductivity and the predictive accuracy of each model was evaluated. The thermal conductivity could be estimated by the Helsing model. The Maxwell model, Bruggeman model and Hashin–Shtrikman model were also in fair agreement using the thermal conductivity value of graphite parallel to the basal planes in graphite. 

Cast iron is assessed as a self-lubricating material under sliding conditions. This is due to the graphite particles distributed in the matrix, which come out from their pocket, and form a tribofilm between the mating surfaces, and by which improve the tribological characteristics. In this study, the directionality and the interaction between the graphite and matrix material was investigated by microindentation and microscratch techniques. The results showed that the graphite is fractured and pushed out from the middle of graphite lamellas as a result of indentation. It was also observed that the graphite orientation below the surface intensely influenced the pushing out behaviour. For the graphite oriented toward the indenter position, the effect was more pronounced. Moreover, it was found that a scratch test can be used to investigate and explain the graphite pushing out tendency. The result was used to explain the directionality and closing tendency of the graphite lamellas during sliding.

The current paper focuses on development of a method for studying micro-scale strains on the microstructure of ferritic cast iron. For this purpose, in-situ tensile tests were done under the optical microscope combined with digital image correlation (DIC). Critical in this development was to be able to achieve a reliable high spatial resolution of strain around microstructural features, such as graphite particles. Measurement of local strain fi elds in cast iron materials have so far been relying on displacement of naturally occurring microstructure patterns such as graphite particles, which limits the spatial resolution of strain measurement. In order to increase the spatial resolution of the measured strain, a pit etching procedure was applied to generate a random speckle pattern on the ferritic matrix. Th e critical challenges of in-situ investigation of microstructural deformation were identifi ed as speckle pattern quality and accurate selection of subset size and strain window size. Th e traceability of this method was studied by benchmarking the measured elastic modulus with that obtained from full-scale tensile test. Th e elastic modulus calculated from average strains, measured by DIC, showed a good agreement with material’s elastic modulus. Th is validates the measured localized strain values and can be used as a validation for modeling of local deformation.

The development of high-performing components is crucial in applications such as heavy vehicleautomotive powertrains. In these applications, strength, weight and thermal conductivity isessential properties. Key materials that may fulfil these requirements include cast irons of differentgrades where in terms of manufacturability and in particular, machinability pearlitic grades aredifficult due to hardness variation, where a fully ferritic matrix would provide an advantage. Toachieve maximum strength a fully ferritic and solid solution strengthened compacted graphite iron(CGI) would provide an interesting alternative to the automotive industry. In the current study, theeffect of Si level on mechanical properties in a fully ferritic material was investigated. The influenceof section thickness on tensile properties and hardness was investigated. The resulting materialwas fully ferritic with limited pearlite content. Section thickness influence on nodularity and hencethe mechanical properties were also investigated.

Abstract Plastic deformation of the matrix during the wear process results in closing the graphite flakes. In this study, the relationship between the deformation of the matrix and the closing tendency of flake graphite was investigated, both qualitatively and quantitatively. Two representative piston rings, which belonged to the same two-stroke marine engine but were operated for different periods of time, were studied. Initial microstructural observations indicated a uniform distribution of graphite flakes on unworn surfaces, whereas worn surfaces demonstrated a tendency towards a preferred orientation. Approximately 40% of the open flakes of the unworn surfaces were closed during sliding, which may result in the deterioration of the self-lubricating capability of cast iron. Moreover, flakes within the orientation range of 0 to 30° relative to the sliding direction showed a maximum closing tendency when subjected to sliding. The closing tendency gradually decreased as the angle increased, approaching a minimum between 30 and 70°. A slight increase in the closing tendency was observed for flakes with orientations between 70 and 90°. A similar trend was observed on both rings. Furthermore, SEM and EDS analysis indicated substantial deformation of the matrix in the area around the flakes. An insignificant corrosion attack was observed on both worn piston ring surfaces.

Teachers from two different disciplines, Materials and manufacturing and Industrial design, are brought together to give a course on masters level. Also the students come from different disciplines. They study two different master programs in Product development, Product development and materials engineering and Industrial design. The course is called Materials and design, and it covers both disciplines. Apart from lectures, computer labs and home assignments, a workshop was arranged where the students during one day solved a task related to product development. The students were divided into groups in such a way that a mixture of students from the two programs was obtained. The workshop was held at a company in order to make the work more realistic. Before they started to solve the task, they were given an introduction to the products made by the company and their applications. The main task was then to investigate the products and come up with ideas about what applications there might be in the future. The result was at the end of the day presented to the company. In this paper, the workshop is described, and comments and reflections from the students and the company are summarized. Finally the teachers involved give their opinion about the result and the pedagogic benefits from such a workshop, and also what to think about for the next time. It appeared that the workshop was an eye-opener to the company at the same time as the students had a fair chance to work in a realistic situation and practice how to use their knowledge. Also for the teachers it was a good experience, not only from a pedagogic viewpoint but also on how to arrange this kind of workshops in the future.

Defective castings produce unnecessary costs for foundries. Common flaw in spheroidal graphite cast iron castings are shrinkage defects. In literature it is suggested that by controlling the graphite precipitation it is possible to suppress the shrinkage propensity of the melt. The most influential way of effecting the graphite precipitation is inoculation. In this work the effectiveness of different commercial inoculant products and inoculation methods in reducing the shrinkage defects on cast component were researched. Significant difference in performance was observed between ladle and stream inoculation methods in preference of stream inoculation. Differences were also seen between different inoculants and how they behaved in combinations when ladle and stream inoculants were added simultaneously. It was observed that not all of the combinations were beneficial. In order to decrease the cost caused by shrinkage defects a proper selection of inoculation method and inoculant is of importance.

The solidification of hypoeutectic gray cast iron starts with the nucleation of primary austenite crystals. Before graphite is nucleated, and the eutectic structure is formed, these crystals start to grow as columnar or equiaxed dendrites. However, very little is known about these dendrites, and especially how they influence the subsequent eutectic structure. Besides, it has previously been shown that the primary solidification structure influences the formation of defects. Shrinkage porosity was found between the dendrites, in the grain boundaries, and the formation of the primary solidification structure was found to influence problems related to metal expansion penetration. Therefore a better understanding about the formation of this structure is of importance. In this work, different inoculants and their influence on the formation of the micro- and macrostructures has been investigated. The inoculants considered are commercially used inoculants, i.e. inoculants used in the foundries, as well as different iron powders. The addition of iron powder is used to promote the primary solidification structure. It is shown that the nucleation of the dendrites is influenced by the amount of iron powder. Secondary dendrite arm spacing is a quantitative measurement in the microstructure related to these dendrites, which in turn depends on the solidification time. Eutectic cell size, on the other hand, is found to depend on secondary dendrite arm spacing. It is shown how the addition of inoculants influences both primary and eutectic solidification structures, and how they are related to each other.