Metal Stream Research Articles

Investigate on the porosity morphology and formation mechanism in laser-MIG hybrid welded joint for 5A06 aluminum alloy with Y-shaped groove

Abstract Laser-MIG hybrid welding is an advancing technology for the joining of aluminum alloy with the medium-thickness owing to the high efficiency and excellent gap bridging ability. In this paper, the laser-MIG hybrid welding experiment for 5A06 aluminum alloy with the thickness of 6.9 mm is carried out. The process porosities and metallurgical porosities in the weld cross-section and tensile fracture are investigated. Furthermore, it is novelty that the formation mechanism of process porosities and metallurgical porosities are comprehensively analyzed based on the porosity morphology after welding, as well as characteristics of molten pool and keyhole during laser-MIG hybrid welding. It is found that the formation of process porosity is owing to the fact that the tip of the keyhole is easily closed by the molten metal stream and separated to form a process bubble. The formation of the metallurgical porosity is attributed to the atomic hydrogen. The inner wall of the metallurgical porosity with the second phase is observed. It is inferred that the formation of second phase is accompanied by the atomic hydrogen. Besides, the area with dense metallurgical porosities and the aggregate metallurgical porosity are formed under the driven force of the liquid metal flow behavior. The formation process of aggregate metallurgical bubble goes through three states, separation state, contact state and aggregate state.

Overcoming Rayleigh–Plateau instabilities: Stabilizing and destabilizing liquid-metal streams via electrochemical oxidation

Liquids typically form droplets when exiting a nozzle. Jets--cylindrical streams of fluid-can form transiently at higher fluid velocities, yet interfacial tension rapidly drives jet breakup into droplets via the Rayleigh-Plateau instability. Liquid metal is an unlikely candidate to form stable jets since it has enormous interfacial tension and low viscosity. We report that electrochemical anodization significantly lowers the effective tension of a stream of metal, transitioning it from droplets to long (long lifetime and length) wires with 100-μm diameters without the need for high velocities. Whereas surface minimization drives Rayleigh-Plateau instabilities, these streams of metal increase in surface area when laid flat upon a surface due to the low tension. The ability to tune interfacial tension over at least three orders of magnitude using modest potential (<1 V) enables new approaches for production of metallic structures at room temperature, on-demand fluid-in-fluid structuring, and new tools for studying and controlling fluid behavior.

Modern status and ways of development of round billet production technology by steel continuous casting

Production of round billets by steel continuous casting, widely used for manufacturing seamless pipes, railway wheels and tyres, quality long rolled products etc., is widely spread in the world steel industry. Constant search for improved design of CCM takes place, separate parts of existing machines are being perfected. An analysis of collected in the world practice experience of solving problems, related to production of round continuously casted billets, enables to choose proper technical solutions for each particular situation, to determine rational parameters of technology. History of development of round continuously casted billets production technology considered. Data on their modern producers presented. Peculiarities of steel continuous casting technology, as well as reasons of defects of round continuously casted billets have been discussed. Classification of basic kinds of cracks of round continuously casted billet presented. Basic problems during production of round continuously casted billets relate to ovality formation, mainly because of unevenness of heat-away in the mold. The increased ovality can lead to formation of internal and external cracks. Ways of solving problems of defects formation and ways of round continuously casted billet technology perfection summarized. Application of methods of mathematical simulation for a technology, which enables to produce defectless billets considered. It was shown, that basic measures to decrease number of billet defects, relate to setting rational parameters of temperature-speed mode, transfer to internal mold profile, corresponding to the billet shrinkage. Another measure is elimination of uneven impact of the liquid metal stream on the solidifying shell in the area of small and big radius. A perspective direction of round continuously casted billets production technology perfection is application of soft reduction methods and electromagnetic stirring of the liquid metal.

Influence of the Design of Metal Receivers of Slab Continuous-Casting Machines on the Motion of Flow in the Tundish in the Case of Deviations of the Metal Stream from the Required Position. Part III. Results of Investigations

Influence of the Design of Metal Receivers of Slab Continuous-Casting Machines on the Motion of Flow in the Tundish in the Case of Deviations of the Metal Stream from the Required Position. Part III. Results of Investigations

Trace Metal Stream Contamination in a Post Peak Water Context: Lessons from the Cordillera Blanca, Peru

As a result of climate warming and glacier recession, glacierized watersheds will experience a decrease in dry season discharge and an increase in wet season discharge, with negative consequences f...

Influence of the Design of Metal Receivers of Slab Continuous-Casting Machines on the Motion of Flow in the Tundish in the Case of Deviations of the Metal Stream from the Required Position. Part I. Statement of the Problem

We study the problem of evaluation of the influence of design of the metal receiver of a large-capacity tundish of slab continuous-casting machine on the decrease in the turbulence of flows in the case of deviation of the metal stream from the required position in the process of casting. We present the results of computer simulations of various types of deviations from the target point of input for the metal stream flowing from the steel-teeming ladle into the tundish. We perform the comparison of the distributions of metal flows in tundishes with metal receivers of different designs. We also give recommendations concerning the possibilities of weakening of the turbulence of flows in the analyzed cases.

Influence of the Design of Metal Receivers of Slab Continuous-Casting Machines on the Motion of Flow in the Tundish in the Case of Deviations of the Metal Stream from the Required Position. Part II. Procedure of Simulation1

Influence of the Design of Metal Receivers of Slab Continuous-Casting Machines on the Motion of Flow in the Tundish in the Case of Deviations of the Metal Stream from the Required Position. Part II. Procedure of Simulation1

The effect of the design of the metal receiver slab CCM on the movement of metal in the intermediate carpet with a deviation of the metal stream from the desired position. Part II Modeling technique

The article is devoted to assessing the influence of the design of a metal receiver in an intermediate ladle of large capacity slab continuous casting machines on reducing turbulence in flows when the metal stream deviates from the required position during casting. The results of computer simulation of industrial variants of displacing a stream of metal from a steel pouring ladle to an intermediate ladle from the target input point are presented. The distribution of metal flows in the tundish is compared with different designs of metal receivers. Recommendations are given for reducing flow turbulence for the cases considered. Ill. 4. Ref. 2.

A Fully Integrated SiGe Radar Sensor for Aerosol Flow Rate Measurements

This letter introduces a bistatic $W$ -band continuous wave radar sensor based on a silicon-germanium (SiGe) transceiver chip with respect to its ability to measure aerosol streams with particles in the micrometer range. The introduced homodyne SiGe sensor relies on a phase-locked loop (PLL)-stabilized oscillator embedded into a monolithic microwave integrated circuit (MMIC), while up until now particle stream monitoring radars are built as waveguide systems. After the radar hardware, including the bistatic antenna configuration, is examined, the physical relationships between the particle stream and the hardware parameters are given. Finally, two different experiments with coarse metallic steel particles and fine coffee powder streams are presented and analyzed.

The effect of the design of the metal receiver slab continuous casting machine on the movement of metal in the intermediate ladle when the metal stream deviates from the desired position. Part I. Formulation of the problem

The article is devoted to assessing the effect of the design of the metal receiver in the intermediate ladle of the large capacity slab continuous casting machine on reducing the turbulence of flows when the metal stream deviates from the required position during casting. The results of computer simulation of industrial variants of displacement of a stream of metal from a steel pouring ladle to an intermediate ladle from the target input point are presented. The distribution of metal flows in the tundish is compared with different designs of metal receivers. Recommendations are given for reducing flow turbulence for the cases considered. Ill. 6. Ref. 5.

The effect of the design of the metal receiver slab continuous casting machine on the movement of metal in the intermediate ladle when the metal stream deviates from the desired position. Part III. Research results

The article is devoted to assessing the influence of the design of a metal receiver in an intermediate ladle of large capacity slab continuous casting machines on reducing turbulence in flows when the metal stream deviates from the required position during casting. The results of computer simulation of industrial variants of displacing a stream of metal from a steel pouring ladle to an intermediate ladle from the target input point are presented. The distribution of metal flows in the tundish is compared with different designs of metal receivers. Recommendations are given for reducing flow turbulence for the cases considered. Ill. 5. Ref. 3.

Low-Pressure Casting of Aluminium AlSi7Mg03 (A356) in Sand and Permanent Molds

Aluminium A356 (AlSi7Mg03) is the most common foundry alloy poured in sand and permanent molds or lost-wax shells. Because of its magnesium content, this alloy responds to a precipitation hardening treatment. The strength and ductility combination of the alloy can be varied at will by changing the temper treatment that follows the solutionizing and quenching of the part. By feeding the mold from the bottom, the low-pressure process provides a tranquil filling of the cavity. A perfect control of the liquid metal stream is provided by programming the pressure rise applied on the melt surface. It compares favorably to the more common gravity casting where a turbulent filling is governed by the geometry of the gating system.

Role of zirconium diboride particles on microstructure and wear behaviour of AA7075 in situ aluminium matrix composites at elevated temperature

ABSTRACTThe present research work examines the impact of temperature on the dry sliding wear behaviour of AA7075 aluminium strengthened zirconium diboride (ZrB2) particulate composite (0, 3, 6, 9 and 12 wt.%). The dry sliding wear behaviour of the AMCs was inspected utilizing a pin-on-disc machine at differing temperatures (40, 60, 120, 180 and 240°C). The wear resistance of AMCs improved with the increased substance of ZrB2 particulates at all test temperatures. The worn surface of the AMC pins was described utilizing FESEM. It was found from the SEM micrographs of worn surface, that at different temperatures, adhesion and metal flow were the prime wear process of the AA7075 composites, while for in situ formed AMCs, metal stream and oxidation were the factors affecting the wear process. The worn surface of the AMCs showed that there was a modification in wear component from abrasive wear to metal flow.

Mathematical Analysis and Mechanical Modeling of an Inoculation System on Feeder Control for Pouring Unit in a Foundry Station

This paper presents on feeder control; the inoculation device has been designed to automatically add inoculating powder to metal stream working with an automatic pouring unit. This system applies a constant dosage of inoculant easily modified by the control unit, with precise repeatability of the process. It incorporates a system of the instant direction of faults at all times, to ensure proper operation. In this project, the human effort is reduced by automating the inoculant feeding mechanism performed in a foundry. By doing pouring in manual manner, it ends up in reducing the rejection of production 2% owing to poor inoculation which disturbs the company's production. This system is used to feed the inoculant to the molten metal in a highly precise amount as per the requirements. After researching various feeding mechanisms, concluded with feeding machine with the help of screw which is more adoptable for desirable number of inoculants to be transferred. The mathematical analysis has been done and it is proven that satisfies the design criterions for modeling of the proposed system. The mechanical modeling is designed in such a way that inoculant occupies in two class of separate hoppers.

Dissolution and erosion behavior of AISI H13 shot sleeve in high pressure die casting process

In high-pressure die casting process (HPDC), shot sleeve undergoes erosion, wear and soldering due to cyclic thermo-mechanical exposure by the molten casting alloy stream with high temperature and high velocity. Gradual deterioration of sleeve surface during service affects the quality of resultant casting, lives of piston and sleeve. It also results in increased cost and downtime. Objective of this work is to study and reduce sleeve surface damage while casting the components weighing between 20 and 40 kg. As initial survey, the worn-out sleeve was used to perform failure analysis to understand erosion mechanism. Simulation study was conducted to estimate impact force of liquid metal stream on sleeve surface at various sprout angles. Dummy pins were made from same steel that of the sleeve - AISI H13 and their erosion response to different surface conditions such as surface roughness, nitrided case depth, and coating chemistry was investigated. Erosion performance of a dummy pin made from steel with increased molybdenum and reduced silicon content was compared with the pins of AISI H13 steel. The pins were observed intermittently for size, weight loss and any crater formation on the surface. All the pins were characterized after subjecting to a maximum number of 4500 casting made. The pins were characterized for microstructure, chemical composition, and phase analysis. Surface roughness and micro-hardness were also measured. Pin made of DIN 1.2367 steel showed increased resistance against erosion, comparative to the pin made of AISI H13 steel under similar testing condition. TiAlN coated pin outperform all other pins in terms of resistance against erosion. Mechanism of progression of erosion in actual shot sleeve is proposed based on experimental design.

Development of the organization of rational schemes for the use of technogenic waste in the processes of off-treatment of steel intermediate

The results of the experimental verification of the efficiency of complex out-of-furnace treatment of low carbon steel using a test mixture based on man-made waste, which is fed partly to the melting unit at the end of the oxidation period of melting and partly by pouring under a stream of liquid metal. is the use of slag-forming materials obtained by joint heat treatment of mixtures of components containing the above mentioned oxides and carbonaceous material of vegetable origin. Their weight ratio in the initial mixture is determined by the purpose and properties of the finished product. The positive technological effects that are achieved by applying the developed method of after-treatment will in future provide favorable conditions for the effective conduct of microalloying, modification, vacuuming and stable casting of low-quality and ultra-low carbon steel. A slight decrease in the temperature of the steel intermediate in the implementation of the method is about 10 - 15 ° C, which is easily compensated for the installation of the ladle, and a slight increase in electricity consumption is compensated by the effects achieved in the processing of low-carbon steel intermediate. Obtaining a higher degree of desulfurization and deoxidation of steel, as well as reducing the contamination of Al2O3 steel and improving the ecological purity of the process can be achieved by reducing the composition of the SHS used in the first stage of processing, the amount of slag aluminothermal production of ferromanganese and complete exclusion of melting, melting weight ratios of powdered waste production of lime, aluminum-thermal slag production of ferromanganese, sludge neutralization of electrocorundum and carbide cr emnia.

Evaluating the material resource efficiency of secondary aluminium production: A Monte Carlo-based decision-support tool

The contamination of aluminium streams during the different life cycle stages by alloy mixing and/or accumulation of foreign elements, in combination with the limited melt purification options during remelting, represents an important limiting factor in recycling. Consequently, in secondary aluminium production, primary aluminium is used to dilute the concentration of the residual elements, and alloying elements are added to adjust the composition to the target alloy specifications. However, adding elements, for which their refinement in a subsequent recycling step is problematic, results in permanent down-cycling or ‘quality losses’. Hence, it is crucial to more efficiently control the composition of the metal streams prior to remelting. This article focuses on the aluminium cascade recycling chain and presents a Monte Carlo-based decision-support tool aiming to: i) identify all feasible clustering solutions per case based on input/output analysis; ii) quantify their environmental effect, and analyze the trade-offs; iii) consider scrap composition uncertainty/variability. Results reveal that primary resource additions can be minimized by optimizing metal sorting, and thus closing the recycling loop more effectively. Case studies are presented to illustrate the different functions of the tool, including examination of the Pareto front, and evaluation of the ‘recyclability’ of a scrap stream or a sorting solution into different alloy systems.

A micro-needle induced strategy for preparation of monodisperse liquid metal droplets in glass capillary microfluidics

Monodisperse micro-sized liquid metal droplets have received considerable attention for developing flexible electronics, microfluidics actuators and reconfigurable devices. Herein we report an innovative and efficient strategy for large-scale preparation of Galinstan liquid metal microdroplets with controllable sizes using a micro-needle induced glass capillary microfluidic device. By inserting a stainless steel micro-needle into the inner liquid metal phase in the glass capillary, the hydrodynamic instability of the liquid metal stream is significantly suppressed to guarantee steady fluid flow before the liquid metal is pinched off by the outer phase flow, giving rise to a stable generation of monodisperse liquid metal microdroplets. The microdroplet size dependence on the flow ratio of the continuous and dispersed-phase is investigated experimentally. A theoretical framework based on the Plateau–Rayleigh instability is proposed to explain the advantage of the micro-needle induced strategy. This strategy has great potential for the generation of high interfacial tension liquid metal emulsions.

Economic and Environmental Evaluation of Aluminium Recycling based on a Belgian Case Study

Abstract The increasing demand for aluminium (Al) has led to the significant growth of secondary Al production. Although Al is one of the most recycled metal streams, the presence of impurities, such as iron, silicon and copper, has limited the environmental and economic benefits of recycling Al. These competing interests have led to the choice of recycling options that is suboptimal. This paper evaluates the economic and environmental effects of recycling different Al scrap qualities based on data collected from a Belgian recycling facility. Observations from the case study show that the profit-driven recycling market has led to a recycling system that does not produce the best environmental impact outcome. Maximising the environmental benefits of material recycling is often secondary to profit generation from the recyclers’ perspective. There is a need for stricter measures, such as environmental tax on primary Al production, to address the environmental and economic challenges in the current recycling systems.

Development perspectives of metal gas-dynamic stirring in a ladle with a side lance application

Blow-off of a liquid metal bath through a lance, located in the bottom part of a ladle wall, is usually considered as one of well-known long time ago variant of steel refining in ladle. However, despite a wide repute and availability of a series of advantages, the technology was not widely spread. An estimation of stirring efficiency and splashes formation at different variants of compressed air supply made. The studies were done at a transparent water model with a color indicator application. It was determined, that upper and bottom lances shifting relating to ladle symmetry axle promotes the stirring intensification and simultaneous decrease of splashes height. The best results were obtained at the simultaneous utilization of asymmetrically located submerged lance and a side lance, oriented in gas-liquid flow direction in the bottom part of the vessel. The side lance is more preferable in maintenance, since for them a ladle fringe is not required as in the case with bottom lances, it is not subjected to falling metal stream action as well as to metal and slag residuals action after tapping finishing. It is possible to provide an improvement of stirring conditions and metal tapping by shifting and inclination of a side lance. Industrial tests showed, that a facility for metal blow off through porous insertions, installed in ladle wall, have a high throughput ability, provide a reliable operation within a course of ladle lining campaign without intermediate repair. It does not require capital outlays and can be recommended for industrial application.