Aluminum Billets Research Articles

A modified Johnson–Cook model for the plastic behavior of metals in ultrasonic vibration-assisted upsetting processes

In this work, we present a constitutive description of the plastic behavior of the metals and alloys under Ultrasonic Vibration (UV). When UV is imposed, it induces a softening effect on the plastic deformation of metals and alloys, referred to as the acoustoplastic phenomenon. The volumetric softening mechanism of the acoustoplasticity must consider stress superposition and acoustic softening. Taking the Johnson–Cook (JC) constitutive model as the reference for metal thermo-plasticity, the flow stress reduction due to UV is introduced by three types of softening terms: subtractive, multiplicative, and coupled. Those different configurations will be quantified via physical and phenomenological assumptions. For the study and validation of the proposed constitutive models, we focus on a well-known material, 6063 aluminum alloy. The ultrasonic vibration is modeled by an assisted upsetting process of an aluminum billet and compared with experiments. The impact of variations of the strain rate, ultrasonic amplitude, and frequency on the softening behavior of the models are analyzed and compared with available experimental results. We find out that the subtractive and coupled models agreed well with the experimental results showing the errors ranging from 2.4–4.8% and 4.4%–8%, respectively. However, the predictive ability of the multiplicative model exhibits large discrepancies at the low stage of strains following the acceptable predictions at high stains. By understanding the impact of the UV on the acoustoplastic deformation of the metals and alloys we can establish a reliable theoretical framework for prospective numerical studies of the UV-assisted manufacturing processes which is the goal of the current research presented here.

Analysis of the influence of dies geometry on the process extrusion force and properties of the extrudate obtained in the process of cold extrusion of 7075 aluminum alloy by the KOBO method

Abstract The KOBO extrusion process is an unconventional method of extrusion based on the phenomenon of superplasticity as an effect of a special state caused by the oscillatory motion of the die at a certain angle a certain frequency. It significantly lowers the extrusion force and makes it possible to extrude lightweight metals and alloys (e.g. aluminum and magnesium alloys) in cold extrusion with high extrusion ratios compared to conventional hot extrusion. This work studies the influence of the tool (die) geometry on process realization parameters and the properties of the extrudate. Experimental studies of cold KOBO extrusion were performed using dies with different face portion geometry. The obtained extrudate obtained from EN-AW 7075 aluminum billets was examined for mechanical properties and macro/microstructure, showing that, with adequate modifications to the tool face part geometry, it is possible to lower the extrusion force and obtain extrudate with desired properties.

The Start-Up Phase of Aluminum Billet Production Using Direct Chill Casting

Direct chill (DC) casting has been considered as one of the promising casting methods that can be used to produce aluminum alloys billet. The process is conducted by pouring aluminum metal into a water-cooled mold. The billet shell begins to form when molten aluminum contact directly with the mold (this is also known as primary cooling). Afterward, the starting block is pulled downwards at a specified casting speed to achieve desired aluminum billet. The start-up phase during the DC casting process is considered a crucial step since it may determine the formation of defects in the casting products. This research aims to investigate the casting defects on the aluminum alloy that were formed during the start-up process of DC casting. The results show that the billet failed to form following the downward movement of starting block. Meanwhile, the billet tended to stick to the mold wall due to several factors, such as too low a pouring temperature, a less-round mold shape, the poor quality of the hot top and graphite ring, and the water that entered the mold during the casting process. It also noted several markers of the casting defects that occurred during the DC casting process such as liquation or bleeding, cold folding, billet stuck in the mold, butt structure, and rough billet surface.

Remelting of Aluminum Scrap Into Billets Using Direct Chill Casting

An as-cast aluminum billet with a diameter of 100 mm has been successfully prepared from aluminum scrap by using direct chill (DC) casting method. This study aims to investigate the microstructure and mechanical properties of such as-cast billets. Four locations along a cross-section of the as-cast billet radius were evaluated. The results show that the structures of the as-cast billet are a thin layer of coarse columnar grains at the solidified shell, feathery grains at the half radius of the billet, and coarse equiaxed grains at the billet center. The grain size tends to decrease from the center to the surface of the as-cast billet. The ultimate tensile strength (UTS) and the hardness values obtained from this research slightly increase from the center to the surface of the as-cast billet. The distribution of Mg, Fe, and Si elements over the cross-section of the as-cast billet is inhomogeneous. The segregation analysis shows that Si has negative segregation towards the surface, positive segregation at the middle, and negative segregation at the center of the as-cast billet. On the other hand, the Mg element is distributed uniformly in small quantities in the cross-section of the as-cast billet.

Quality assessment of hybrid aluminum billets jointing using torsional forging method

The producing of hybrid (composite) workpieces made of AMg2 and AMg6 wrought aluminum alloys by torsion forging under deformation conditions at room temperature is considered. The results of the microstructure and microhardness of the composite samples after the plastic deformation are presented. Conclusions are drawn about the possibility of connecting these pairs of materials using torsion forging.

Research of Three-High Screw Rolling of Aluminum Billets with Copper Inserts at Different Rolls Feed Angles

Three-high screw-rolling of aluminum alloy ingots was carried out at 12- and 20-degrees rolls feed angles. The ingots had two copper, cylindrical inserts oriented along the ingot axis: the center of one insert coincided with the ingot’s center, and the center of the other insert coincided with the ingot’s half-radius. The effect of the rolls feed angle value on the aluminum and copper microstructure as well as the hardness formation was established. X-ray study and three-dimensional modeling allowed the copper insert twisting angle to be estimated along the rolled billet axis. It also allowed detection of the number of breaks of the insert located in the ingot’s center and the insert located in the ingot’s half-radius depending on the rolls feed angle value.

Development of 400 kW Class Aluminum Billet Heater Using HTS Magnet

In this paper, design, fabrication, and test results of the demonstration device for 400 kW-class aluminum billet heating using the HTS magnet were reported. Based on our user's request, the target of the demonstration device was to heat the aluminum billet of 155 mm in diameter and 500 mm in length from room temperature to 500 ℃ within 60 seconds. In the heating test using the demonstration device, it was demonstrated that the input heating power to the aluminum billet of 155 mm in diameter and 500 mm long was more than 400 kW. Based on the measured data of the heating tests, the heating efficiency was estimated to be 74.5%. It was shown that at least 30% reduction of energy consumption could be possible compared to conventional induction heating devices.

Comparison of microstructure and mechanical properties of industrial pure aluminum produced by powder metallurgy and conventional rolling

Aluminum alloys are produced by different manufacturing techniques and each technique produces a unique microstructure. One of the most versatile manufacturing methods is powder metallurgy (P/M) because it produces a final fine or ultrafine grain microstructure. But it requires powder consolidation and densification processes after P/M. In the other side, Hot Isostatic Pressing (HIP) is now recognized as a very interesting technique to densify advanced materials with a high potential. The aims of this work are: to produce an AA1100 aluminum billet by powder densification followed by HIP and to compare its microstructure and mechanical properties against the ones of an AA1100 aluminum plate produced by conventional rolling. The mechanical properties were measured using tensile test and Charpy test. The results show that the tensile strength of the P/M+HIP sample is higher than the one of the aluminum plate, but the yield strengths are similar. In the other hand the impact toughness results are very different from each other.

高温超電導マグネットを用いたアルミ押出成形用400 kW級直流誘導加熱装置の開発

We have been conducting research and development of the DC induction heating device of aluminum billet using HTS magnets. In this R&D, following the development of main components such as the HTS magnet system, the heating control system and the mechanism for grasping and rotating the aluminum billet, the demonstration device for 400 kW-class billet heater was developed and the heating power of over 400 kW was demonstrated. In this study, as the final step of the R&D, we conducted a continuous repetitive heating test and evaluation of the electromagnetic and mechanical influence due to the heating operation on the HTS coil.

Performance Assessment of Using Multilayer Inductors in Induction Installations for Heating Aluminum Billets

A mathematical model for numerically analyzing the electrical characteristics of a multilayer inductor – billet system is developed. The model is based on the finite element method and implemented in the ELCUT software package. The system electrical characteristics depending on different billet sizes, inductor geometry, gap sizes, and system design area sizes are obtained. The influence of end effects and magnetic core on the multilayer inductor – billet system is studied. Based on the simulation results, recommendations on improving the energy efficiency of induction installations for heating aluminum billets owing to smaller losses achieved by modifying the multilayer inductor designs have been developed.

Enhanced strength-ductility combination in the cold-rolled spark plasma sintered pure aluminium by FSP

In the present study, the microstructural characterization and tensile deformation behaviour of pure aluminium (Al) billet manufactured through the combination of spark plasma sintering (SPS), cold rolling, and friction stir processing (FSP) are reported. The grain size is reduced from ~17 μm in the SPSed specimen (S) to ~7 μm after cold rolling, further refined to ~1 μm by FSP. The modified microstructure includes fine equiaxed grains with more than ~77% sharp high angle grain boundaries (HAGBs), a large grain aspect ratio (~ 0.5), and a higher fraction of recrystallized grains (~ 85%). The superior grain boundary characteristics are attributed to the discontinuous dynamic recrystallization during the FSP of the rolled SPSed billet. The ultimate tensile strength (UTS) of pure Al billet is increased from ~124 MPa in the as-SPSed condition to ~131 MPa (~ 6% increment) after the combination of SPS, cold rolling, and FSP. On the other hand, percentage elongation increases from ~32.3% in the cold-rolled SPSed condition to ~43.2% after FSP indicating an overall increment of ~34% in the ductility. The HAGB and dislocation strengthening with the contribution of ~45% and ~ 17% in the strengthening are primarily responsible for the improved tensile properties of the FSPed specimen, respectively. The high strength-ductility combination of the pure Al billets with the proposed approach set up a benchmark for the efficacy of various expensive reinforcements during the composite fabrication through SPS. • Microstructural modification of cold rolled SPSed pure Al by FSP is reported. • Extremely fine grains (~1 μm) with 77% HAGBs are obtained after FSP. • Enhanced strength-ductility combination is achieved.

Fabrication and Test of HTS Magnet for Induction Heating Device in Aluminum Extrusion Processing

This paper reported the fabrication and the test results of the high temperature superconducting (HTS) magnet developed for the aluminum billet heater for aluminum extrusion processing. In this magnet, the HTS coils were combined with iron cores, because the required magnetic field in the working region was about 1T. Two HTS coils wound directly on the convex shape iron cores were fabricated. The HTS coils were made by the no-insulation winding of REBCO tape with the YOROI-coil technique. Each of them was separately installed in an individual cryostat. Two HTS coils with iron cores were disposed oppositely to each other and were magnetically connected by a C-shape yoke placed in room temperature. The HTS coil was cooled down to about 15 K by the GM cryocooler in the initial cooling. The magnetic field of 1.06 T at the center of the heating region was stably generated with the rated current of 200 A. It was also demonstrated that the HTS magnet could be charged up to 300 A without quench. According to the observation of the electromagnetic force direction from the outside of the cryostat, it was confirmed the validity of the force balance design of the magnet.

Influence of the number of FSP passes on the strength-ductility synergy of cold-rolled spark plasma sintered pure aluminum

The present investigation aims to understand the effect of the number of friction stir processing (FSP) passes (1–3 passes) on the microstructural evolution and strength-ductility synergy of the cold-rolled spark plasma sintered (SPSed) pure aluminum billet. The increase in FSP passes improved the uniform elongation from ~18% in the 1-pass FSP to ~22% in the 3-pass FSPed specimen. Contrastingly, the yield strength (YS) decreased from ~103 MPa in the 1-pass FSP to ~97 MPa in the 3-pass FSP. Thus, an optimum combination of YS (~99 MPa) and uniform elongation (~20%) is achieved for the 2-pass FSPed specimens. The enhanced strength-ductility combination of the 2-pass FSPed samples is attributed to the fine equiaxed grains (average grain size of ~1 μm) with more than ~77% sharp high angle grain boundaries (HAGBs), large grain aspect ratio (~0.5), and a higher fraction of recrystallized grains (~85%) that is obtained by the discontinuous dynamic recrystallization during the FSP. The theoretical calculations indicate grain boundary or the Hall-Petch strengthening as the dominant mechanism in the FSPed specimens. The high strength-ductility combination of the pure Al billets with the proposed approach set up a benchmark for the efficacy of various expensive reinforcements during the composite fabrication through SPS.

T5 Tracking Cardiac Output During Burn Resuscitation via Pulse Wave Analysis

IntroductionUrine output (UOP) still remains the primary endpoint utilized as a surrogate for cardiac output (CO) and adequacy of perfusion during burn resuscitation. The role of arterial blood pressure (BP) waveform as a guiding tool for burn resuscitation has not been rigorously explored. As we move toward developing and validating novel endpoint to complement UOP, we compared the potential of pulse wave analysis (PWA) of arterial BP waveforms for estimating cardiac output (CO) and stroke volume (SV) in a large animal model of 40% total body surface area (TBSA) burns with varying resuscitation paradigms.MethodsAnesthetized swine were instrumented and hemorrhaged 15% of their blood volume, and sustained a 40% TBSA full-thickness contact burn with aluminum billets. Animals were kept in a surgical ICU setting overnight, during which anesthesia was maintained with a combination of propofol, ketamine, and fentanyl. Animals were randomized to 3 different intravenous fluid (lactated Ringer’s, LR) levels: under resuscitation with no IV fluids, adequate resuscitation protocolized with a clinical decision support tool, or over resuscitation with a starting rate of 500mL/hour. We computed 20 surrogate measures of CO and SV (10 each) via PWA of arterial BP, and calibrated them to reference CO via thermo-dilution and SV on a subject-by-subject basis. Surrogate performance was quantified in terms of correlation coefficient and root-mean-squared error (RMSE) relative to reference CO and SV.ResultsAnimals received 0±0, 4.4±1.6, and 9.1±1.3 mL/kg/% TBSA in the under, adequate, and over resuscitation groups (p=0.0036), respectively. Among the ten surrogate measures of CO and SV, 4 surrogates had positive proportionality to reference CO and SV consistently. The best surrogate measure of CO and SV was [mean BP-diastolic BP]/[heart period] and [mean BP-diastolic BP], respectively, which yielded r value of 0.82+/-0.19 and RMSE of 0.23+/-0.14 lpm for CO and r value of 0.85+/-0.17 and RMSE of 2.7+/-2.0 ml for SV (Fig. 1).ConclusionsThe initial results suggest that PWA-based surrogates of CO and SV have the potential to track reference CO and SV in extremes of resuscitation post-burn. The current model produces under-resuscitated, adequately resuscitated, and over-resuscitated animals, making it possible to rigorously examine the efficacy of PWA-based tracking of CO and SV in a wide spectrum of burn resuscitation scenarios. Hence, PWA may provide metrics useful for developing surrogates of CO and SV as novel treatment endpoints of burn resuscitation that indicate perfusion and volume status of burn injury patients.

Energy Consumption Characteristics for Design Parameters of Permanent Magnet-Based Al Billet Heater

This study analyzed design factors to maximize energy efficiency, via numerical analysis, through an examination of the characteristics of a heating system that uses permanent magnets and is employed for preheating in the aluminum cladding extrusion process. The design parameters of the billet heater using permanent magnets are the magnetic flux direction, the number of magnets, clearance, and eccentricity. The magnetic flux density, current density, power loss, temperature, and energy consumption characteristics were examined using the results of the parameter variations. Numerical analysis for the base model was conducted, and it was experimentally verified that the aluminum billet reached 450 °C in about 260 s, and the temperature error at that time was about 2%. The analysis results show that the optimal factor conditions vary significantly depending on the magnetic force direction of the permanent magnet, that is, the circumferential (tangential) and centrifugal (normal) directions. Furthermore, eccentricity has an effect on efficiency in general, and the narrower the clearance was between the magnet and billet, the higher the efficiency achieved. That is, it was confirmed that the power loss increased by about 1.79% in the four permanent magnets to the tangential model, and increased by about 10.51% in the 12 permanent magnets to the tangential model when an eccentricity of 2 mm was applied at a clearance of 2.5 mm. In addition, the optimal design parameters of a system that heats aluminum billets with a diameter of 60 mm and a length of 70 mm were proposed, and the importance of the design parameters was revealed. In this study, it was found that 12 magnets were the most effective when the magnetic flux pole direction was tangential.

Aluminum Billets Heat Treatment Using Hot Flue Gas in Batch Homogenizing Preheating Furnace for Energy Efficiency and Cycle Time Reduction in Cast House

Aluminum Billets Heat Treatment Using Hot Flue Gas in Batch Homogenizing Preheating Furnace for Energy Efficiency and Cycle Time Reduction in Cast House

2D hybrid magneto-thermal model for PM induction heating device with rotating movement

A new 2D-hybrid model in cylindrical coordinates intended for the study of a transient magneto-thermal coupled problem is proposed. This model is used to evaluate the spatiotemporal distribution of temperature in rotating aluminum billets heated by permanent magnets induction-heating device (PMIHD). The proposed hybrid model consists of coupling an exact analytical solution of the 2D magneto-harmonic field to a 2D transient thermal analysis where the temperature dependence of electrical and thermal physical properties of the heated billet is considered. Based on the separation variables technique, the analytical solution of magneto-harmonic problem serves to evaluate the induced current and the resulting power density loss distribution in the nonmagnetic billet. Furthermore, the 2D transient thermal analysis, based on the lumped thermal network model, is developed in radial and axial directions of the heated billet. In order to validate the 2D hybrid magneto-thermal model, the performances of the studied PMIHD are compared with those obtained with Finite Element Method (FEM).

Влияние СОЖ и режимов обработки на шероховатость поверхности при торцевом фрезеровании заготовок из алюминиевых сплавов

Within the framework of these studies, experimental studies are carried out on the effect of using coolants of various types — synthetic «BIOSIL-S», semi-synthetic «SP3» and water-based «Smalta-4» — on the roughness of the machined surface of an aluminum billet during milling. The roughness of the machined surface is evaluated by the Ra parameter using a MarSurf PS1 portable profilometer. As a result of the research, it is found that coolants affect the quality of the resulting surface in different ways. The best surface quality is obtained at a cutting speed of V=283 m/min and a feed of S=0,02 mm/tooth using a BIOSIL-S coolant, which is due to rational cutting conditions and the physical properties of the coolant.

Conjugated Heat Exchange in Heat Treatment of Aluminum Ingots Simulation

Casting aluminum to obtain semi-finished products - round ingots, due to uneven cooling in the mold, leads to various defects that affect further machining. To eliminate such defects, heat treatment is carried out - homogenization annealing. One of the homogenization important stages is the cooling of the ingots after heating at a rate that does not lead to the ingot quenching. The cooling medium is air. Knowing the conditions of heat exchange between the cooling air and the high-temperature aluminum billet makes it possible to obtain the ingot’s necessary physical and mechanical properties. The article describes the developed mathematical model of conjugate heat transfer during homogenization annealing of aluminum ingot. It allows analytically calculating the temperature of the ingots depending on the cooling time. To verify the data obtained by the mathematical model, the conjugate heat transfer in the ANSYS program was simulated.

The Effect of Knowledge Management Implementation on the Organizational Performance through Learning Organization at PT Inalum (Persero)

PT Indonesia Asahan Aluminium (Persero) or Inalum is a State-Owned Enterprise (BUMN) which is a pioneer company and the only one in Indonesia engaged in the production of Primary Aluminium (ingots, billets and alloys). Currently, Inalum is faced with problems with 42.39% of employees having period of employment less than 5 years in 2018. Conditions of productivity performance also declined from 2014 which was 135.35 tons of aluminium per employee per year to 117.67 tons of aluminium per employee per year in 2018. This becomes basic policy to implement knowledge management and learning organizations within the company. The purpose of this research is to find out and analyze the effect of knowledge management with the focus of tacit knowledge on organizational performance through learning organizations. The independent variable in this study is tacit knowledge management, the dependent variable is organizational performance, and the intervening variable is the learning organization. Data collection using a questionnaire with a total sample of 100 respondents. This research uses SEM analysis method which has previously been tested for validity and reliability. The results of this study indicate that tacit knowledge management has a positive and significant effect on organizational performance, tacit knowledge management has a positive and significant effect on learning organizations, learning organization has a positive and significant effect on organizational performance and tacit knowledge management has a positive and significant effect on organizational performance through learning organizations. Keywords: Knowledge Management, Tacit Knowledge Management, Learning Organization, and Organizational Performance.