Metal Outflow Research Articles

A tight N/O–potential relation in star-forming galaxies

ABSTRACT We report a significantly tighter trend between gaseous N/O and $M_*/R_\mathrm{ e}$ (a proxy for gravitational potential) than has previously been reported between gaseous metallicity and $M_*/R_\mathrm{ e}$, for star-forming galaxies in the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey. We argue this result to be a consequence of deeper potential wells conferring greater resistance to metal outflows while also being associated with earlier star-formation histories, combined with N/O being comparatively unaffected by metal-poor inflows. The potential–N/O relation thus appears to be both more resistant to short time-scale baryonic processes and also more reflective of a galaxy’s chemical evolution state, when compared to previously considered relations.

Boosting galactic outflows with enhanced resolution

ABSTRACT We study how better resolving the cooling length of galactic outflows affect their energetics. We perform radiative-hydrodynamical galaxy formation simulations of an isolated dwarf galaxy ($M_{\star }=10^{8}\, \mbox{M}_\mathrm{\odot }$) with the ramses-rtz code, accounting for non-equilibrium cooling and chemistry coupled to radiative transfer. Our simulations reach a spatial resolution of $18 \, \mathrm{pc}$ in the interstellar medium (ISM) using a traditional quasi-Lagrangian scheme. We further implement a new adaptive mesh refinement strategy to resolve the local gas cooling length, allowing us to gradually increase the resolution in the stellar-feedback-powered outflows, from $\ge 200 \, \mathrm{pc}$ to $18 \, \mathrm{pc}$. The propagation of outflows into the inner circumgalactic medium is significantly modified by this additional resolution, but the ISM, star formation, and feedback remain by and large the same. With increasing resolution in the diffuse gas, the hot outflowing phase ($T \gt {8} \times 10^{4} \, \mathrm{K}$) systematically reaches overall higher temperatures and stays hotter for longer as it propagates outwards. This leads to two-fold increases in the time-averaged mass and metal outflow loading factors away from the galaxy ($r=5\, \mathrm{kpc}$), a five-fold increase in the average energy loading factor, and a ≈50 per cent increase in the number of sightlines with $N_{\rm{O {\small VI}}} \ge 10^{13}\, \mathrm{cm}^{-2}$. Such a significant boost to the energetics of outflows without new feedback mechanisms or channels strongly motivates future studies quantifying the efficiency with which better-resolved multiphase outflows regulate galactic star formation in a cosmological context.

FOREVER22: Gas and metal outflow from massive galaxies in protocluster regions

Abstract We study gas and metal outflow from massive galaxies in protocluster regions at z = 3 − 9 by using the results of FOREVER22 simulation projects. Our simulations contain massive haloes with $M_{\rm h} \gtrsim 10^{13}~\rm {\rm M}_{\odot }$, showing high star formation rates of $> 100~\rm {\rm M}_{\odot }~yr^{-1}$ and hosting supermassive black holes with $M_{\rm BH} \gtrsim 10^{8}~\rm {\rm M}_{\odot }$. We show that the mass loading factor (ηM) sensitively depends on the halo mass and it is ηM = 1.2 (9.2) for $M_{\rm h}= 10^{13}~(10^{11})~{\rm {\rm M}_{\odot }}$. Once the halo mass exceeds $\sim 10^{12.5}~\rm {\rm {\rm M}_{\odot }}$, the outflow velocity of the gas rapidly decreases near a virial radius, and the gas returns to a galactic centre finally as a fountain flow. Also, the metal inflow and outflow rates sensitively depend on the halo mass and redshift. At z = 3, the inflow rate becomes larger than the outflow one if $M_{\rm h}\gtrsim 10^{13.0}~{\rm {\rm M}_{\odot }}$. Thus, we suggest that massive haloes cannot be efficient metal enrichment sources beyond virial radii that will be probed in future observations, e.g., studies of metal absorption lines with the Prime Focus Spectrograph on the Subaru telescope.

Thermally-induced microstructure evolution of Ag/AlN nano-multilayers: The role of annealing atmosphere on the Ag outflow driving force

Thermally-induced microstructure and property alteration of nano-multilayer (NML) coatings are of principal importance for industrial applications. The phenomenon of surface outflow of confined metal is highly promising for the development of NML-based brazing fillers for joining technology. Annealing conditions, such as temperature and atmosphere, are the principal factors defining the brazing filler outflow characteristics besides the NML design. The present study addresses the microstructure evolution of Ag/AlN NMLs during thermal treatment in various atmospheres (Ar, air, vacuum). The mechanisms of the NML bulk microstructure modification do not change with the annealing atmosphere. Channels in the NML volume are formed at each annealing atmosphere by grain boundary grooving, which act as pathways for Ag atoms transport to the NML surface, causing metal outflow. However, a significant effect of the atmosphere on the metal outflow and shape of the particles formed was observed. Annealing in an inert atmosphere and vacuum results in a moderate surface outflow of Ag atoms. On the contrary, heat treatment in air results in a chemical interaction of nanolayers with oxygen, substantially intensifying the outflow. This interaction is rationalized by considering the surface energies of Ag/AlN and Ag/Al2O3 interfaces, where the latter are formed upon annealing. Based on grooving angles, the upper bound Ag(111)/AlN(0001) interface energy estimate of 0.54 J/m2 at 650 °C was derived, which is significantly lower than the average magnitude of Ag/Al2O3 interface energy (~ 2 J/m2 for crystalline phases). Besides, the annealing atmosphere has an impact on the shape (elongated whiskers, bulk faceted crystals) of Ag particles formed on the NML surface by modifying silver surface energies.The proper choice of a heat treatment atmosphere provides an innovative pathway for controlling the Ag surface outflow in Ag/AlN NMLs for novel low-temperature joining applications.

Trace metal geochemistry sediments from the Dibamba River, SW Cameroon: Implication for heavy metal assessment and origin

Sediment quality and trace metal accumulation are two of the most pressing issues facing the aquatic ecosystem around the world. Twenty-four (24) samples of stream sediments were collected along the Dibamba River, in the economic and industrial capital of Cameroon, to judge the trace metal levels in this river flowing near the city of Douala. Trace metal concentrations were disclosed with an ICP-MS on two different grain size fractions (very fine-grained sand and clay). The sediments indicate possible adverse effects of trace metals on surrounding biota as elements like Cr, Cu, Ni, Zn, Pb, and Hg show positive enrichment of greater than 1 when compared to background values from the upper continental crust (UCC) and sediment quality factors such as TEL (threshold effects level), PEL (probable effects level), ERL (effects range low), and ERM (effects range medium) values. The sediments show values of Degree of contamination (DC = 2–4), Pollution load index (PI = 1–2), and individual potential risk (EI = 92–219) indicating moderate pollution and ecological risk. Statistical and multivariate analyses point to both anthropogenic and geogenic sources for the heavy metals in the Dibamba stream sediments. The geogenic origin of the heavy metals is linked to the weathering of gneiss and migmatite found in the river banks. This study found low to mild levels of metal pollution and toxicity in the sediment, but it also warned that the continued development of nearby industries and businesses, the provision of transportation services, and waste disposal activities could result in a gradual outflow and accumulation of metals in the sediment, endangering the aquatic ecosystem.

Regulation of Star Formation by a Hot Circumgalactic Medium

Galactic outflows driven by supernovae (SNe) are thought to be a powerful regulator of a galaxy’s star-forming efficiency. Mass, energy, and metal outflows (η M , η E , and η Z , here normalized by the star formation rate, the SNe energy, and metal production rates, respectively) shape galaxy properties by both ejecting gas and metals out of the galaxy and by heating the circumgalactic medium (CGM), preventing future accretion. Traditionally, models have assumed that galaxies self-regulate by ejecting a large fraction of the gas, which enters the interstellar medium (ISM), although whether such high mass loadings agree with observations is still unclear. To better understand how the relative importance of ejective (i.e., high mass loading) versus preventative (i.e., high energy loading) feedback affects the present-day properties of galaxies, we develop a simple gas-regulator model of galaxy evolution, where the stellar mass, ISM, and CGM are modeled as distinct reservoirs which exchange mass, metals, and energy at different rates within a growing halo. Focusing on the halo mass range from 1010 to 1012 M ⊙, we demonstrate that, with reasonable parameter choices, we can reproduce the stellar-to-halo mass relation and the ISM-to-stellar mass relation with low-mass-loaded (η M ∼ 0.1–10) but high-energy-loaded (η E ∼ 0.1–1) winds, with self-regulation occurring primarily through heating and cooling of the CGM. We show that the model predictions are robust against changes to the mass loading of outflows but are quite sensitive to our choice of the energy loading, preferring η E ∼ 1 for the lowest-mass halos and ∼0.1 for Milky Way–like halos.

SUBSTANTIATION OF ENERGY-POWER PARAMETERS OF THE STEEL LADLE SLIDE GATE CATAPULT

The theoretical and experimental studies were performed in the design and energy-power parameters of the catapult, which is part of the steel ladle slide gate and ensures the destruction of the crust, which often forms in the surface layer of the loose starting mixture at the inlet of the outlet channel and prevents the beginning of the free outflow of liquid metal when the ladle tundish is first opened. A method was proposed for calculating the dimensions of flat elastic elements of a catapult, taking into account the dimensions of slide gates installed on the steel casting ladles with a capacity of 100–300 tons, as well as the strength of the resulting crust. The obtained calculated dependences are based on the law of conservation of energy of the studied catapult system. It is shown that its use would eliminate the need to use oxygen for burning the solid bulkhead and thereby eliminate the intense destruction of the working walls of the steel outlet channel, contamination of the cast metal with exogenous inclusions and violation of the required velocity mode of its flow from the ladle. Compared with known foreign analogues, the proposed catapult favourably differs in its simple design, low cost, low operating costs and reusable application. This is achieved by moving its power unit out of the steel outlet channel of the ladle gate

Non-axisymmetric die-less spinning using ball-crown-shape roller

The non-axisymmetric cone has broad application prospects. However, the severe wall thickness thinning has been the bottleneck problem restricting the application of non-axisymmetric parts which are manufactured via die-less shear spinning. In order to control the spun wall thickness distribution, the ball-crown-shape roller is adopted to carry out the non-axisymmetric spinning. The spun workpiece with the non-axisymmetric cone shape is obtained, and the deviation of the maximum and minimum half cone angles α and β between the experimental results and the theoretical values is no more than 4.11%. The wall thicknesses are much greater than that of the shear spinning value with the corresponding half cone angles, and basically maintain at (even locally exceed) the initial blank thickness. At the same time, the half cone angle is considered to have small effect on the wall thickness distribution. The finite element model for this spinning process is established and verified to reveal the wall thickness distribution mechanism which is illustrated as that the BCSR causes the complementary relationship between the metal outflow and circumferential replenishment in the each half cone angle direction.

Microstructure-Property Control in Functional Materials by Multilayer Design

Smart microstructure and interface design in nanomultilayers allows to tailor physical properties like thermal stability, thermal conductivity and directional metal outflow for targeted applications. In this work, selected examples of nanomultilayer systems, constituted of alternating nanolayers of metals and/or nitrides, as precisely fabricated with variable textures, microstructures, grain sizes and internal stresses are presented. The role of the microstructure and stress state on selected functional properties is shown.

Matematička i kompjuterska simulacija pojave udubljenja tokom hladnog kombinovanog izvlačenja

The article is considered a comparative analysis for predicting defect such as dimple by energy method of power balance, upper bound method and finite element method. The upper bound method takes into account the geometrical position and dimension of the dimple, the criterion for the formation in dimple by energy method of power balance is the presence of a minimum point in the function of relative pressure on the relative velocity of metal outflow in the vertical direction. New engineering calculations for the relative pressure are developed in combined radialbackward extrusion process by using a kinematic module with fillet. A comparative analysis of the obtained data has been carried out by energy method of power balance, upper bound method, computer simulation by Qform 2/3D program and experimental data. Rationality of using the energy method of power balance in view of its efficiency and the possibility of taking into account various friction conditions and the presence of fillet on the matrix, as well as smaller deviations from the results of finite element simulation and experimental data have been defined. Providing more conditions that are favorable for friction in the bottom of the billet and in the flange area in comparison with the friction conditions on the glass wall contribute to delay in the dimple appearance. It was found that the radius of fillet makes it possible to delay the dimple appearance by the approximately (0,4 ÷ 0.5R) mm for the entered radius of fillet R. This allows us to expand the possibilities of obtaining parts with a flange by combined radial-backward extrusion without the formation of a defect such as dimple.

Characterizing mass, momentum, energy, and metal outflow rates of multiphase galactic winds in the FIRE-2 cosmological simulations

ABSTRACT We characterize mass, momentum, energy, and metal outflow rates of multiphase galactic winds in a suite of FIRE-2 cosmological ‘zoom-in’ simulations from the Feedback in Realistic Environments (FIRE) project. We analyse simulations of low-mass dwarfs, intermediate-mass dwarfs, Milky Way-mass haloes, and high-redshift massive haloes. Consistent with previous work, we find that dwarfs eject about 100 times more gas from their interstellar medium (ISM) than they form in stars, while this mass ‘loading factor’ drops below one in massive galaxies. Most of the mass is carried by the hot phase (>105 K) in massive haloes and the warm phase (103−105 K) in dwarfs; cold outflows (<103 K) are negligible except in high-redshift dwarfs. Energy, momentum, and metal loading factors from the ISM are of order unity in dwarfs and significantly lower in more massive haloes. Hot outflows have 2−5 × higher specific energy than needed to escape from the gravitational potential of dwarf haloes; indeed, in dwarfs, the mass, momentum, and metal outflow rates increase with radius whereas energy is roughly conserved, indicating swept up halo gas. Burst-averaged mass loading factors tend to be larger during more powerful star formation episodes and when the inner halo is not virialized, but we see effectively no trend with the dense ISM gas fraction. We discuss how our results can guide future controlled numerical experiments that aim to elucidate the key parameters governing galactic winds and the resulting associated preventative feedback.

Characterizing the Circumgalactic Medium of the Lowest-mass Galaxies: A Case Study of IC 1613

Abstract Using 10 sight lines observed with the Hubble Space Telescope/Cosmic Origins Spectrograph, we study the circumgalactic medium (CGM) and outflows of IC 1613, which is a low-mass (M * ∼ 108 M ⊙), dwarf irregular galaxy on the outskirts of the Local Group. Among the sight lines, four are pointed toward UV-bright stars in IC 1613, and the other six sight lines are background QSOs at impact parameters from 6 kpc (<0.1R 200) to 61 kpc (0.6R 200). We detect a number of Si ii, Si iii, Si iv, C ii, and C iv absorbers, most of which have velocities less than the escape velocity of IC 1613 and thus are gravitationally bound. The line strengths of these ion absorbers are consistent with the CGM absorbers detected in dwarf galaxies at low redshifts. Assuming that Si ii, Si iii, and Si iv comprise nearly 100% of the total silicon, we find 3% (∼8 × 103 M ⊙), 2% (∼7 × 103 M ⊙), and 32%–42% [∼(1.0–1.3) × 105 M ⊙] of the silicon mass in the stars, interstellar medium, and within 0.6R 200 of the CGM of IC 1613. We also estimate the metal outflow rate to be and the instantaneous metal mass loading factor to be η Z ≥ 0.004, which are in broad agreement with available observation and simulation values. This work is the first time a dwarf galaxy of such low mass is probed by a number of both QSO and stellar sight lines, and it shows that the CGM of low-mass, gas-rich galaxies can be a large reservoir enriched with metals from past and ongoing outflows.

Predicting the shape formation of hollow parts with a flange in the process of combined radial-reverse extrusion

The simulation of the process of combined radial reverse extrusion of hollow parts with a flange has established two fundamentally different, in terms of the components of the kinematic modules, calculation schemes CDZ-1.i and CDZ-2.j, taking into consideration the possible shape of the boundary of the section of a metal flow inside a workpiece. The comparison of the dependences of the optimal relative rate of metal outflow in the opposite direction for different schemes indicates significant differences in the resulting values in the course of the deformation process. The relevance of this study is due to making it easier to evaluate the use of the combined extrusion process to produce hollow parts with a flange while maintaining the required dimensions compared to simple deformation schemes. We have identified the lack of detailed studies into the technologies for the introduction of combined extrusion schemes, as well as the absence of technological recommendations for determining the force regime and the shape formation of a semi-finished article. The process of the combined extrusion of hollow parts with a flange was investigated, thereby selecting different types based on the nature of the metal flow depending on the geometric ratios of the deformation process. We have obtained experimental data on the gradual shape formation of a semi-finished product in the process of deformation at different geometric ratios. The limits of using estimation schemes of the process have been defined to obtain data on the increments in a semi-finished product, including in terms of predicting the formation of a shrinkage cavity in the bottom part. It is recommended that a condition of selecting the appropriate scheme should be the condition for a minimum value of the reduced pressure of deformation p i < p j . The resulting recommendations make it easier to predict the shape formation and the force mode of extrusion (a deviation from experimentally obtained data can be reduced to 10 %), which would contribute to evaluating the rationality of the combined extrusion processes while ensuring the required dimensions of a part

Characteristics of heavy metal pollution in road runoff in the Nanjing urban area, East China.

An extensive field survey was conducted in four types of road area to study heavy metals in road runoff. Eleven rainfall events were monitored from February 2011 to March 2012, which were classified into four categories according to the relationship between peak of the rainfall amount, rainfall duration, and average rainfall intensity. Runoff samples were collected from overpass sections, college areas, residential areas, and road sidewalks. Heavy metal concentrations were obtained to investigate the outflow laws governing heavy metals in runoff. The concentration fluctuations of seven heavy metals were monitored to assess the influence of rainfall characteristics on metal concentrations. To estimate the impact of heavy metals on the water environment, the event mean concentrations (EMCs) were determined to describe the overall pollution degree of heavy metal in runoff, and then the EMC values of heavy metals in runoff were compared with surface water environmental quality standard thresholds. The results indicate that the EMC values of heavy metals varied widely in different rainfall fields and under the same rainfall at different sampling points. Average rainfall intensity has a significant impact on the EMC of heavy metal outflow, followed by maximum rainfall intensity and rainfall amount.

Maskless Patterning of Metal Outflow in Alternating Metal/Ceramic Multiple Nanolayers by Femtosecond Laser Irradiation

In this work, solid-state metal transport from internal metal nanolayers onto the surface of metal/ceramic nano-multi-layers (NMLs) has been directed in a controlled way by femtosecond (fs) laser irradiation and subsequent low temperature thermal annealing. Laser irradiation induced modifications of the NML microstructures and stress states can be limited within the first few top nanolayers due to the focused laser energy input at the metal/ceramic interface by exploiting the local plasmonic effect. Accompanied laser peening can further refine the crystallites and introduce compressive stress at the laser-irradiated region, which reduces the activation energies for vacancy formation and migration of metal atoms in the nano-confinement. Patterned Cu surface nanostructures (outflow) appear selectively along the laser path after air annealing at temperatures down to 360 ℃. For the solid-state diffusion of Cu in confinement, in-plane metal transport along the Cu-AlN interfaces is much faster than the outward ...

Local Deformation-Controlled Fast Directional Metal Outflow in Metal/Ceramic Nanolayer Sandwiches upon Low Temperature Annealing.

Precise nanoindentation on AlN/Cu/AlN nanolayer sandwiches has been conducted by using an atomic force microscope to promote fast and directional metal (Cu) outflow upon heating at low temperatures. Local plastic deformation during indentation results in the generation of high defect densities and stress gradients, which not only effectively reduce the activation energies for fast in-plane diffusion but also direct the in-plane transport of confined Cu to the indent location. In addition, a steep chemical potential gradient of O will be established across the AlN barrier upon exposure to air, which drives fast outward diffusion of Cu along defective pathways in the top AlN layer at the indent location. Selective and fast Cu metal outflow can thus be achieved at the indent locations upon annealing at a relatively low temperature of 350 °C for 5 min in air. The microstructures and phase boundaries of the AlN barrier and confined Cu nanolayers are unperturbed outside the plastically deformed region and remain metastable after annealing at 350 °C. By changing the surface processing modes, patterned nanoparticles and isolated nanowire structures can be fabricated straightforwardly. Such local deformation-controlled directional mass transport phenomena can be utilized to manipulate materials down to the atomic scale for designing functional nanoarchitectures for nanophotonic and nanoelectronic applications.

Hydrotransport-Oriented Zn, Cu, and Pb Behavior Assessment and Source Identification in the River Network of a Historically Mined Area in the Hokuroku Basin, Northeast Japan.

Aquatic ecosystems continuously receive potentially hazardous heavy metals from natural and anthropogenic sources. Focusing on the origin of heavy metals, this study aims to estimate the load contribution of tributaries from individual watershed and human drainage and to dissect the source of heavy metals, as commonly required for environmental impact assessment. Using integrated water dynamics, Geographic Information System (GIS), and chemical analysis, we identified and evaluated the heavy metal sources of the Kosaka river system in Hokuroku basin, which is a historically mined area in Northeast Japan, both in the high-water and low-water seasons. The migration and diffusion behaviors of heavy metals along with hydro-transport were analyzed, and the effects of mining activities on regional water quality both in the high-water and low-water seasons were clarified. The results indicate that Zn pollution was obvious in the Kosaka River network, especially in the downstream area. The spatial heterogeneity of heavy metal outflows from tributary watersheds was obvious, and the variations had strong correlations with mine site locations. The heavy metal flows in the mainstream increased sharply in the vicinity downstream of the Kosaka refinery drainage outlets. Compared to the low-water season, the influences of human drainage were slighter in high-water season, with lower contribution rates due to the dilution effect of the greater water discharge. Downscale sampling is effective to identify pollutant sources in regional basins.

Derivation of engineering formulas in order to calculate energy-power parameters and a shape change in a semi-finished product in the process of combined extrusion

The possibilities of using and embedding kinematic trapezoid modules with curvilinear boundaries of different shapes were explored. Based on the energy method, the generalized formulas for calculating the power of deformation forces inside the axial trapezoidal kinematic module were derived. Different types of selecting the functions that describe a curvilinear boundary of the axial trapezoidal module were identified. We have analyzed the possibilities of using known techniques for the linearization of integrand dependences in order to calculate the power of deformation forces when it is impossible to obtain a given magnitude in the form of an analytical function. The ways to derive engineering formulas for the computation of components of reduced pressure inside an axial trapezoidal kinematic module were proposed. Based on the energy method, we obtained formulas for the calculation of a step-by-step change in the shape of a semi-finished product under assumption within the axial trapezoidal kinematic module. We modeled the process of combined extrusion of hollow parts with a flange and established regularities in shape formation depending on geometrical parameters. The data about a step-by-step change in the shape of a semi-finished product during deformation were obtained. A comparative analysis of calculation schemes for the rectilinear trapezoidal kinematic module and with a curvilinear boundary under assumption within the studied module was performed. It was confirmed that the reported ways for obtaining engineering formulas, as well as the algorithm for the calculation of processes of combined extrusion that is based on them, simplify the development of technological recommendations. This applies both to determining the force mode of extrusion and preliminary assessment of a change in the shape of a semi-finished product with the possibility to control a metal outflow in the process of deformation

Investigation into the Influence of the Degree of Grinding of the Ingot Grain Structure of the 6063 Alloy on Its Plasticity, Extruding Parameters, and Properties of Extruded Profiles

As a result of an analysis of scientific and technical literature and practical data, it is found that changing the casting parameters for ingots using different designs of crystallizers makes it possible to vary the degree of refinement of the grain structure of ingots in a sufficiently wide range, which should be reflected in the conditions of extrusion of aluminum alloy profiles and their physicomechanical characteristics. Therefore, the purpose of this research is to assess the influence of the degree of grinding for the ingot grain structure of alloy 6063 on the deformation and speed parameters of extrusion and the mechanical properties of profiles. Several parties of 178-mm diameter ingots of 6063 alloy cast under industrial conditions, as well as profiles formed by direct extrusion using a horizontal hydraulic press with a force of 18 MN subjected to quenching and aging, are used. The grain size in homogenized ingots is evaluated by optical microscopy using an Olimpus optical microscope, and tests of mechanical properties are performed using an Inspect 20 kN-1 universal testing machine. It is established that the initial grain size in the ingot structure strongly affects both the ingot plasticity during extrusion and final structure and mechanical properties of profiled products made of aluminum alloys. When analyzing these results, it is possible to conclude that an increase in strength characteristics of extruded products made of ingots with a more refined structure is due to the fact that a fine grain is retained in the metal structure after its deformation, while the cast metal plasticity rises with an increase in the degree of grinding the grain structure in the ingot. In connection with this fact, an increase in the efficiency of quenching the profiled products and metal outflow rate during the extrusion take place.

STUDY INTO THE INFLUENCE OF THE GRAIN STRUCTURE REFINEMENT DEGREE OF ALLOY 6063 INGOTS ON THEIR PLASTICITY, EXTRUSION PARAMETERS AND PROPERTIES OF EXTRUDED PROFILES

The analysis of scientific and technical literature and practical data made it possible to found that changes in casting parameters for ingots using different mold designs allows varying the degree of ingot grain structure refinement in a sufficiently wide range, which should be reflected in the conditions of aluminum alloy profile extrusion as well as physical and mechanical properties of these profiles. Therefore, the purpose of the research was to assess the influence of the degree of grain structure refinement for Alloy 6063 ingots on extrusion deformation and speed parameters and mechanical properties of profiles produced. The study used several batches of Alloy 6063 ingots 178 mm in diameter cast under industrial conditions, as well as profiles obtained by direct extrusion on a 18 MN horizontal hydraulic press subjected to quenching and aging. The grain size in homogenized ingots was estimated by light microscopy using the Olimpus optical microscope, and mechanical properties tests were carried out using the Inspect 20 kN-1 universal test machine. It was found that the initial grain size in the ingot structure exerts a significant influence both on ingot plasticity during extrusion, and on the final structure and mechanical properties of profile products made of aluminum alloys. Having analyzed the results obtained, we can conclude that the increase in strength characteristics of products extruded from ingots with a more refined structure is due to the fact that fine grains are retained in the structure of metal after its deformation, and cast metal plasticity increases with the degree of grain structure refinement in the ingot. This leads to the higher efficiency of profile product hardening and metal outflow rate during extrusion.