Factors Influencing Dephosphorization of Low Carbon Steel in Converter

A 300-metric ton converter in a steel plant in China was studied. The influence of factors such as slag composition and temperature in the smelting process on the dephosphorization effect was statistically analyzed. The dephosphorization ability of slag increased firstly and then decreased with the increase of temperature, basicity and FeO content. Low-temperature, high-basicity and high-oxidizing slag are thermodynamically beneficial to promote the dephosphorization reaction, but the basicity is higher than 4.0, and the temperature is higher than 1640 °C are not conducive to the slag to obtain better fluidity. At the same time, too high FeO content will increase the activity coefficient of P2O5, thereby increasing its activity, which is not conducive to the progress of the dephosphorization reaction. As the end point content of carbon decreases, the oxygen content increases and the phosphorus content decreases. A very low carbon content is not conducive to metal yield and temperature control.

Research of process factors increasing metal yield during aluminum waste remelting

The article presents the results of research determining the most effective technologies for increasing metal yield in the processing of aluminum-containing waste. In particular, peculiarities of the processes of melting aluminum alloys were analyzed using complex methods of furnace and off-furnace processing of charge material containing an increased amount of shovelling scrap and swarf. Studies on the impact of charge preparation and aluminum remelting technology were carried out in SAT-0,16 and IAT-0,4 furnaces on the АК12М2 alloy. Experiments proved that batchwise loading 20 kg of swarf briquette preheated to 300–400 °C into the SAT-0,16 furnace with the addition of flux (composition: NaCl – 50 %; KCl –35 %, Na3AlF6 – 15 %) in the amount of 3 % of total metal mass is the most efficient technology. This technology makes it possible to achieve a metal yield of about 94 %. The study of the remelting technology influence on IAT-0,4 furnace metal yield showed that the greatest effect can be obtained in case of furnace charge (95 kg swarf briquette) by batches of 2 kg into the 7 kg liquid bath with modifier flux (composition: NaCl – 62 %; KCl – 13 %, NaF – 25 %) added in the amount of 2 % from the total metal mass. This technology provides up to 93.5 % of metal yield. Data from 10 series of 5–9 melts were also analyzed with the comparison of metal yield results depending on the mass of briquetted swarf charged into the furnace. A histogram of the change in the porosity of AK12M2 and AK9 samples depending on the content of swarf in the charge (from 0 to 45 %) during remelting. It was found that an increase in the content of swarf in the charge, all other things being equal, leads to an increase in the average porosity score, which indicates the need for additional refining of such melts.

Discrimination of heavy elements originating from Pop III stars in z = 3 intergalactic medium

ABSTRACT We investigate the distribution of metals in the cosmological volume at $z$ ∼ 3, in particular, provided by massive Population III (Pop III) stars using a cosmological N-body simulation in which a model of Pop III star formation is implemented. Owing to the simulation, we can choose minihaloes where Pop III star formation occurs at $z$ > 10 and obtain the spatial distribution of the metals at lower redshifts. To evaluate the amount of heavy elements provided by Pop III stars, we consider metal yield of pair-instability or core-collapse supernovae (SNe) explosions of massive stars. By comparing our results to the Illustris-1 simulation, we find that heavy elements provided by Pop III stars often dominate those from galaxies in low-density regions. The median value of the volume averaged metallicity is $Z\sim 10^{-4.5 - -2} \, \mathrm{Z}_{\odot }$ at the regions. Spectroscopic observations with the next generation telescopes are expected to detect the metals imprinted on quasar spectra.

OBTAINING OF FERROSILICOCHROMIUM POWDER ALLOY BY SILICOTHERMIC REDUCTION AND STUDY OF THE MECHANISM OF THIS PROCESS

The process of obtaining a powder ferrosilicochromic alloy by the method of silicothermic reduction of local chromites and slags of copper smelters was investigated. The mechanism of this process has been studied. It is established that the best results are obtained in the case of slag / chromite ratio = 1: 1, when an alloy with microdispersed structure and high strength is obtained. The optimum composition of the resulting alloy is as follows: 35,1% Fe; 36,35% Si and 28,53% Cr, with a metal yield of 98,4%. The obtained alloy powder can be used as an acidified and alloying additive to chromium- and silicon-containing stainless composite materials. The aspects of the process for obtaining FeSiCr alloy have been developed. The maximum temperature (Tc) and the linear propagation velocity of the combustion wave (Uv) are determined graphically. The mechanism of the formation of FeSiCr in the SHS process is explained.

Welding of Internally Clad X65 Pipes With Precipitation Strengthened Ni-Based Filler Metals

X65 steel pipes internally clad with Alloy 625 used in subsea oil extraction are normally welded together with Alloy 625 filler metal. For pipe reeling applications, DNV-OS-F101 requires pipe girth welds to overmatch base metal yield strength with 100 MPa. Since Alloy 625 filler metal does not meet this requirement, Ni-base super alloys 718 and 282 were considered as potential welding consumables for reeling applications. The solidification behavior in weld metal of these alloys diluted with Alloy 625 pipe ID cladding was evaluated using thermodynamic simulations. The response to precipitation hardening by multiple reheat cycles was studied by producing multilayer buildups with cold metal transfer (CMT) and pulsed gas metal arc welding (GMAWp) processes. Weld buildup of Alloy 718 exhibited insufficient hardening response and yield strength, while Alloy 282 met the DNV overmatch requirement. Successful narrow groove welding of X65 pipes with Alloy 282 was performed using CMT process. Welding parameter optimization allowed resolving centerline solidification cracking and lack of fusion defects. The weld metal yield strength was lower than in the multipass buildup, which was attributed to lower number of reheats in groove welding. Meeting the overmatch requirement for yield strength in Alloy 282 groove welds requires further parameter optimization.

New Technology of Combined Machining of Aluminium Alloys

Basic information and research results of the process combined rolling-extruding have been represented, which have been used to create new energy-saving technologies for obtaining of long deformed semi-finished products of small cross-section. It has been shown that such combined processing technologies may be applicable for the machining of low ductility and low-tech aluminium alloys with high metal yield and high productivity.