The electroslag remelting process (ESR) is important because it provides better control of the solidification microstructure and chemical homogeneity; it also enables greater cleanliness and better mechanical properties. The manufactured high-alloyed steels and other alloys with a controlled chemical composition are used in aerospace, in thermal-and nuclear-power plants, in chemical engineering, for military equipment, special tools, etc. An overview and the basics of the ESR process are presented in this paper.

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During routine metallographic investigations of some fully processed, non-oriented, electrical steel sheets, the typical MnS inclusions were not observed in the microstructures. In the MS-type sulphides, the manganese was substituted by magnesium. A systematic ex-situ characterisation of the non-metallic, magnesium-containing inclusions was carried out and the origin of the inclusions was proposed. The inclusions' chemistry and morphology were investigated by light microscopy and field-emission scanning electron microscopy. The non-metallic, magnesium-containing inclusions were classified as complex sulphides, oxides and spinels. Magnesium was also detected as being co-precipitated with other non-metallic inclusions, like nitrides. The form of the co-precipitated magnesium inclusions was predetermined by the shape of the thermodynamically most stable inclusions.KEY WORDS: magnesium; non-metallic inclusions; non-oriented electrical steel.

Mathematical descriptions of true stress/true strain curves, experimentally obtained on cylindrical specimens under hot compressive conditions, are of great importance and are widely investigated. An additional black-box modelling approach using transfer functions (TF) is tested. For tested 51CrV4 steel, a TF of third order is employed for description of true stress (output) depending on the strain rate (input). Sets of TF coefficients are determined using numerical optimization techniques for each testing temperature and strain rate. To avoid scattering of TF parameters, time in Laplacian transformation is replaced with strain, while TF input is the strain rate. Obtained models cover deformations starting practically from zero to 0.7. Average absolute relative error for models based on TF of the third order and of the second order are 0.93% and 3.64%.

The solidification behaviors of laboratory cast austenitic SS2343 stainless steel in terms of the volume fraction of δ-ferrite in the as-cast state and its transformation after subsequent annealing were investigated. Monitoring of morphological transformations of δ-ferrite in the microstructure show the progress of δ-ferrite dissolution. Annealing tests were conducted at 1050 °C, 1150 °C and 1250 °C with soaking times of 5 and 40 min. The thermodynamic prediction and metallographic identification of δ-ferrite are presented. The ferrite fractions were measured using a magnetic method and determined to be in the range between 10.7% and 14.6%. The volume share of δ-ferrite decreased with an increase in temperature and the time of annealing. About 50–55% the δ-ferrite was effectively transformed. The δ-ferrite phase, originally present in a dendritic morphology, tends to break up and spheroidize. The morphology varies from vermicular, lacy and acicular shapes to globular for higher temperatures and for longer exposure times. In the δ-ferrite after annealing, concentrations of Cr and Mo decrease, and conversely the concentration of Ni increase, all by small, but significant, amounts. The observed changes in the solute concentration can be explained in terms of the transformation of ferrite into austenite and sigma phases.