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.

Study of a Late Bronze Age Casting Mould and Its Black Residue by 3D Imaging, pXRF, SEM-EDS, Micro-FTIR and Micro-Raman

In the present work, a fragment of a stone mould recently found in Galicia (NW Spain) was studied by multiple analytical techniques approach involving 3D optical imaging reconstruction to obtain data about the shape of the mould, typology of artefact produced, and distribution of a black residue at the surface of the mould and pXRF, SEM-EDS, micro-FTIR, and micro-Raman to investigate the nature of the black residue. The study shows that the mould was likely used for socketed axes with a side loop, was originally composed of two valves and one core, and that it might have been subjected to a repair during use. The black residue is distributed in the carved surface and spreads to nearby surfaces as a result of the use of the mould. The alloy cast in the mould was a ternary bronze (Cu + Sn + Pb). The analyses by SEM-EDS of black residue covering the surface did show the presence of scattered micro particles with P and Ca, and micro-Raman analysis detected the presence of a carbon black of animal source, while micro-FTIR analysis detected remains of proteins, oxalates, and hydroxyapatite. These results are amongst the very few studies made on black residues of ancient moulds and suggest that the mould was dressed with a carbon black of animal origin, such as burned bones, prior to metal casting, probably used as a coating agent to improve the casting and artefact recovery.

Microstructure and elevated temperature mechanical properties of Mg-6Gd-3Y-0.5Zr alloy cast by PEP–SET sand mold

The present work cast a complex Mg-6Gd-3Y-0.5Zr alloy component in a polybenzylic ether phenolic resin (PEP-SET) sand mold using by differential pressure casting. Microstructural characterization was carried out on the castings in the states of as-cast, solution treatment and aging treatment. Their mechanical properties were examined at elevated temperatures. The studied Mg alloy showed noticeably high tensile strengths up to 473 K, followed by a significant decrease with further increasing the testing temperatures. Its mechanical properties at elevated temperatures were compared with those of WE43 alloy fabricated under identical casting conditions.

The Influence of H2SO4- NaCl Electrolyte Composition to the Electrochemical Noise Behaviour of a High-Alloy Cast Steel

In this study, the influence of varying sulphuric acid – sodium chloride electrolyte composition to the electrochemical noise behaviour of a high-alloy cast steel was analysed. The noise analysis was carried out in a bare 0.1 M sulphuric acid solution, in a pure 5 wt.% sodium chloride solution and three solutions with defined ratios of both. The electrochemical current noise signal was recorded with a sampling rate of 100 Hz for 1 hour in each test solution. For the identification of the frequency content of notified characteristic transients, the current-time records were analysed by the continuous wavelet transform (CWT). The characteristic transients were extracted from the noise signal for a further analysis of their frequency and amplitude characteristics. The results show high-frequency transients in the bare sulphuric acid and low-frequency transients in the pure sodium chloride solution. In the combined electrolyte solutions the portion of low-frequency components increases when the NaCl content increases and indicates the enhancing influence of localised damage evolution processes at the steel surface.