Improvement in steel smelting by studying melt behavior

Analysis shows that the disequilibrium of melts may be used to characterize metal quality and to optimize smelting technology. For the production of pipe steel by means of a superpowerful DSP-135 arc furnace, a ladle-furnace unit, a vacuum-treatment system, and a continuous-casting machine, the sources of melt disequilibrium are studied in relation to the properties of the final steel. That provides the basis for the development of parameters characterizing different stages of the process. The proposed improvements in smelting technology are shown to be very efficient. © 2013 Allerton Press, Inc

Исследование физико-химических характеристик расплавов коррозионностойких сталей, легированных азотом

Physicochemical characteristics of the melt of nitrogen-alloyed steel of 04Kh20N6G11M2AFB grade (nitrogen content 0.47 0.49 %) were investigated by the method of torsional vibrations of a crucible with a metal in the atmosphere providing a stable nitrogen content during the experiment (80 % nitrogen and 20 % helium). Using sensitivity of the method to aggregate state of the test substance, at a heating rate of 0.0033 0.0050 K/s, the liquidus temperatures were experimentally determined for 04Kh20N6G11M2AFB steel (1660 1666 K) and lownitrogen steel ([N] = 0.063 %) with identical content of other elements (1685 1690 K). This made it possible to recommend the value of the coefficient - 60 K/% [N] for the calculated assessment of the effect of nitrogen on liquidus temperature of complex and high-alloy steels. It is shown that the viscosity of the melt of 04Kh20N6G11M2AFB steel has a relatively high level ((11.5 ± 0.7) 10-7 m2/s) in comparison with the traditional ((8.2 ± 0.2) 10-7 m2/s) austenitic steels with a relatively small partial effect of nitrogen. A significant non-equilibrium of the melt structural state of this steel was established by high-temperature viscometry methods. Comparative analysis of polytherms and isotherms of the melt kinematic viscosity for 04Kh20N6G11M2AFB steel and its low nitrogenous ([N] = 0.063 %) analogue made it possible to conclude that the presence of nitrogen at concentrations close to saturation plays a decisive role in the level of non-equilibrium of the melt and low rate of its relaxation. It was confirmed as a result of special experiments on the saturation of low-nitrogen steel with nitrogen, during which a sharp increase in non-equilibrium of the melt structural state was recorded with achievement of nitrogen concentration in the metal of limiting values (0.45 0.50 %). The principal possibility of increasing and stabilizing the operational properties of corrosion resistant nitrogen-alloyed steels is indicated by reducing non-equilibrium of the melt structural state by eliminating the excess of nitrogen concentration limits for the considered chemical composition. © 2020 National University of Science and Technology MISIS. All rights reserved

Accessing the strong interaction between Λ baryons and charged kaons with the femtoscopy technique at the LHC

The interaction between Λ baryons and kaons/antikaons is a crucial ingredient for the strangeness S=0 and S=-2 sector of the meson–baryon interaction at low energies. In particular, the Lambda-Kbar might help in understanding the origin of states such as the Csi(1620), whose nature and properties are still under debate. Experimental data on Lambda-K and Lambda-Kbar systems are scarce, leading to large uncertainties and tension between the available theoretical predictions constrained by such data. In this Letter we present the measurements of Λ–KK− and Λ–KK+ correlations obtained in the high-multiplicity triggered data sample in pp collisions at sqrt(s) = 13 TeV recorded by ALICE at the LHC. The correlation function for both pairs is modeled using the Lednický–Lyuboshits analytical formula and the corresponding scattering parameters are extracted. The Λ–KK+ correlations show the presence of several structures at relative momenta k* above 200 MeV/c, compatible with the Ω baryon, the , and resonances decaying into Λ–K− pairs. The low k* region in the Λ–KK+ also exhibits the presence of the state, expected to strongly couple to the measured pair. The presented data allow to access the ΛK+ and ΛK− strong interaction with an unprecedented precision and deliver the first experimental observation of the decaying into ΛK−