Mechanical properties of ductile cast iron relation to the charge elements

Summary In many recent publications on the optimisation of alloys in terms of, among other things, their strength and resistance to wear, a trend can be observed to look for new alloying additives to improve these properties. This paper presents the results of a study on the effect of changes in the chemical composition of EN-GJS-500-7 ductile alloy cast iron on its mechanical properties. In order to confirm the effect of alloying additives on the mechanical properties of the alloys, industrial melting of cast iron was carried out and samples were taken for testing. The smelts were not subjected to heat treatment, but were carried out differently in terms of the feedstock used and based on the analysis of the cooling curve using an automated smelting technology enabling the elimination of degraded Chunky graphite. The influence of the shape of graphite precipitates on tensile strength and hardness was determined, and spectroscopic studies of the microstructure of cast irons were carried out.

Coupled Electro-Chemical-Soil Model to Evaluate the Influence of Soil Aeration on Underground Metal Pipe Corrosion

A mechanistic understanding of the process of underground corrosion is important for modeling pipeline deterioration. In this study, a time-dependent multiscale numerical model incorporating electrochemistry and soil hydrology is developed. The model realistically simulates soil moisture and aeration conditions and their influence on anodic/cathodic activity without prior definition. In this manner, both micro- and macrocell corrosion and their evolution with time are simulated along with the effects of differential aeration. The model was validated with low-alloy cast iron corrosion data from the United States National Bureau of Standards corrosion exposure study. The effect of soil aeration in controlling soil corrosiveness was simulated with suitable boundary conditions. It was demonstrated that macrocells arising due to differential aeration can lead to elevated levels of corrosion in pipelines, especially in fairly aerated soils.