Research progress on semi-continuous casting of magnesium alloys under external field

High-performance magnesium alloys are moving towards a trend of being produced on a large scale and in an integrated manner.The foundational key to their successful production is the high-quality cast ingots.Magnesium alloys produced through the conventional semi-continuous casting process inevitably contain casting defects,which makes it challenging to manufacture high-quality ingots.The integration of external field assisted controlled solidification technology,which combines physical fields such as electromagnetic and ultrasonic fields with traditional semi-continuous casting processes,enables the production of high-quality magnesium alloy ingots characterized by a homogeneous microstructure and absence of cracks.This article mainly summarizes the technical principles of those external field assisted casting process.The focus is on elaborating the refinement mechanism of different types of electromagnetic fields,ultrasonic fields,and combined physical fields during the solidification of magnesium alloys.Finally,the development prospects of producing highquality magnesium alloy ingots through semi-continuous casting under the external field were discussed.

Direct-chill semi-continuous casting process of three-layer composite ingot of 4045/3004/4045 aluminum alloys

Three-layer composite ingot of 4045/3004/4045 aluminum alloys was prepared by direct-chill semi-continuous casting process,the temperature field distribution near the composite interface,macro-morphology,microstructure and composition distribution of the composite interface were investigated.The results show that semi-solid layer with a certain thickness forms near the interface due to the effect of cooling plate,which ensures successful implementation of casting the composite ingot.Two different aluminum alloys are well bonded metallurgically.The mechanical properties of composite interface were measured,the tensile and shearing strengths of composite interface are 105 and 88 MPa,respectively,which proves that the composite interface is a kind of metallurgical bonding.

Development and application of titanium alloy casting technology in China

The development and research of titanium cast alloy and its casting technology, especially its application in aeronautical industry in China are presented. The technology of molding, melting and casting of titanium alloy, casting quality control are introduced. The existing problems and development trend in titanium alloy casting technology are also discussed.

Status quo and development trend of lost foam casting technology

Lost foam casting(LFC)technology has been widely applied to cast iron and cast steel.However,the development of LFC for Al and Mg alloys was relatively slower than that for cast iron and cast steel.The application of LFC to Al and Mg alloys needs more effort,especially in China.In this paper,the development history of LFC is reviewed,and the application situations of LFC to Al and Mg alloys are mainly discussed.Meanwhile,the key problems of LFC for Al and Mg alloys are also pointed out.Finally,the prospects for LFC technology are discussed,and some special new LFC technologies are introduced for casting Al and Mg alloys.In future,the development trends of green LFC technology mainly focus on the special new LFC methods,metal material,coating,heat treatment,new foam materials as well as purification technology of tail gas,etc.

Study on Semi-Continuous Technology System for Soft Material Stripping in Large Surface Mines

Continuous and semi-continuous mining technology has become the main trend of modern surface mines in the world. According to the deposit characteristics of coal basin in China and Chinese situation,this paper discussed the new semi-continuous technology── shovel - transfer wagon-belt conveyor and its application prospect in large surface coal mines in China.

Effects of casting process on microstructures and flow stress behavior of Mg-9Gd-3Y-1.5Zn-0.8Zr semi-continuous casting billets

Mg-9Gd-3Y-1.5Zn-0.8Zr alloys own high strength,good heat and corrosion resistance.However,it is difficult for the fabrication of large-scale billets,due to the poor deformation ability and strong hot-crack tendency.This work investigated the casting process on the microstructures and flow stress behaviors of the semi-continuous casting billets for the fabrication of large-scale Mg-9Gd-3Y-1.5Zn-0.8Zr billets.The casting process(electromagnetic intensity and casting speed)shows outstanding effects on the microstructures and flow stress behavior of the billets.The billets with the specific casting process(I=68 A,V=65 mm/min)exhibit uniform microstructures and good deformation uniformity.

Effect of high-intensity ultrasonic field on process of semi-continuous casting for AZ80 magnesium alloy billets

Under the high-intensity ultrasonic field,AZ80 magnesium alloy was semi-continuously cast.The effects of ultrasonic intensity on the as-cast microstructures and mechanical properties were investigated.The results show that the microstructures of the alloy cast under high-intensity ultrasonic field are fine and uniform,and the grains are equiaxed,rose-shaped or globular with an average size of 257μm.High-intensity field significantly decreases the grain size,changes the morphologies of theβ-Mg17Al12 phases and reduces their area fraction.It is also shown that a proper increase in ultrasonic intensity is helpful to obtain fine,uniform and equiaxed as-cast microstructures.The optimum ultrasonic parameters are that frequency is 20 kHz and ultrasonic intensity is 1 368 W.The mechanical tests show that the mechanical properties of the as-cast AZ80 magnesium alloy billets cast under ultrasonic field are greatly improved,and with increasing the ultrasonic intensity,the mechanical properties of the entire alloy billets are much higher and more uniform than those of the alloy without ultrasonic field.

Effects of heat treatment on microstructure and mechanical properties of Mg-8Gd-3Y-0.5Zr(wt.%)alloy fabricated by semi-continuous casting

The microstucture, mechanical properties and fracture behaviors of semi-continuous cast Mg-8Gd- 3Y-0.5Zr （wt.%, GW83K） alloy after different heat treatments were investigated. Almost all the eutectic compounds were dissolved into the matrix and there was no evident grain growth after optimum solution treatment at 500 ~C for 4 h. Further ageing at low temperatures led to significant precipitation hardening, which strengthened the alloy. Peak-aged at 200℃, the alloy had the highest ultimate tensile strength （UTS） and lowest elongation at 395 MPa and 2.8%, respectively. When aged at 225℃ for 15 h, the alloy exhibited prominent mechanical performance with UTS and elongation of 363 MPa and 5.8 %, respectively. With regard to microstructure and tensile properties, the processes of 500℃, 4 h ＋ 225℃, 15 h are selected as the optimal heat treatment conditions. The alloy under different conditions shows different fracture behaviors： in the as-cast alloy, a quasi-cleavage pattern is observed; after solution treatment, the alloy exhibits a trans-granular quasi-cleavage fracture; after being peak-aged at 200℃ and 225℃, the fracture mode is a mixed mode of trans-granular and inter-granular fracture, in which the inter-granular mode is dominant in the alloy peak-aged at 200℃.

Application of 3D stereoscopic visualization technology in casting aspect

3D stereoscopic visualization technology is coming into more and more common use in the field of entertainment,and this technology is also beginning to cut a striking figure in casting industry and scientific research.The history,fundamental principle,and devices of 3D stereoscopic visualization technology are reviewed in this paper.The authors’research achievements on the 3D stereoscopic visualization technology in the modeling and simulation of the casting process are presented.This technology can be used for the observation of complex 3D solid models of castings and the simulated results of solidification processes such as temperature,fluid flow,displacement,stress strain and microstructure,as well as the predicted defects such as shrinkage/porosity,cracks,and deformation.It can also be used for other areas relating to 3D models,such as assembling of dies,cores,etc.Several cases are given to compare the illustration of simulated results by traditional images and red-blue 3D stereoscopic images.The spatial shape is observed better by the new method.The prospect of3D stereoscopic visualization in the casting aspect is discussed as well.The need for aided-viewing devices is still the most prominent problem of 3D stereoscopic visualization technology.However,3D stereoscopic visualization represents the tendency of visualization technology in the future;and as the problem is solved in the years ahead,great breakthroughs will certainly be made for its application in casting design and modeling and simulation of the casting processes.

Microstructure and mechanical properties of AZ31 alloy ingot fabricated by semi-continuous casting

The AZ31 alloy ingot with diameter of 110 mm and length of 3500 mm was fabricated successfully. The compositions and microstructure morphologies of the ingot at different locations were performed, which indicated that the chemical composition distributed homogeneously through the whole alloy ingot and the average grain size increased from the surface to the center. The results of the EDS and element face-scanning illustrated that the eutectic compounds mainly consisted of fl-Mg17Al12 and a small amount of fl-Mgl7（AlZn）12. Furthermore, slight improvements of the strength and ductility were observed from the center to the surface along the axial direction of the alloy ingot, while both the strength and elongation to failure of the samples along the radial direction are higher than that along the axial direction. The fine grain strengthening was the main contributors to the strength of the as-casted AZ31 alloy.

Property Characteristics of a TiB_(2P)/Al Composite Fabricated by Squeeze Casting Technology

TiB2P/Al composite was successfully fabricated by squeeze casting technology.Its mechanical and tribological properties were evaluated .The elimination of Ti-Al intermetallic compound was confirmed by X-ray diffraction （XRD）studies.At 45% volume fraction ,the bending strength at ambient temperature was 934 MPa.And the fracture modes included ductile failure of Al matrix and brittle fracture of TiB2 pqrticles.In dry sliding wear mode ,severe plastic deformation and adhesive wear were found on te worn surfaces of the SiCP/Al composite .But no obvious characteristics of adhesion or abrasion wear were observed on that of the TiB2P/Al composites .At the stedady stage ,the friction coefficient of the SiCP/Al composite was about 0.6 .While that of TiB2P/Al composite was only only about 0.16-0.17.

Preparation of QTi4.3-4Graghite Composite by Semi-solid Casting Technology

The electromagnetic-mechanical stirring technology was employed for preparing QTi4.3-4 graghite composite slurry,and QTi4.3-4 graghite composite with uniform distribution of graphite particles was prepared uring the semi-solid casting technology successfully.The structure of this QTi4.3-4graphite composite was studied and the condition for uniform distribution of graphite particles was got.The experimental results show that there exists a linear relationship between the solid fraction and the stirring temperature of QTi4.3-4graphite slurry.With the decreasing of stirring temperature,the solid fraction of QTi4.3-4 graghite slurry increases constantly.In casting,with the increasing of solid fraction of QTi4.3-4 graphite slurry.the agglomeration of graphite particles is removed gradually.When the solid fraction is higher than 40%,graphite particles can distribute evenly in QTi4.3-4 graghite composite.

Effect of Middle-frequency Electromagnetic Field on the Semi-continuous Casting for ZK60 Billets

The semi-continuous casting of ZK60 magnesium alloy under different middle frequency electromagnetic field conditions was examined.Effects of middle frequency electromagnetic field on microstructure,precipitations and tensile properties are investigated.The results show that the microstructures of ZK60 magnesium alloy are refined and distribution uniformity of precipitations is observed after applying the middle frequency electromagnetic field.And the tensile properties of the billets produced by middle frequency electromagnetic field are increased.

Recent Development of Lost Foam Casting Technology Comment on the 7th Chinese Lost Foam Casting Symposium

The 7th Chinese Lost Foam Casting (LFC) Symposium & the 1st LFC Technology Exposition were held on May 21-23 at Nanjing University of Aeronautics and Astronautics (NUAA), and the conference theme was "Recent development of lost foam casting technology". Prof. TAO Jie, the Executive Chairman of the conference and the Vice Director of LFC Committee of Foundry Institution of Chinese Mechanical Engineering Society(FICMES), chaired the inauguration. Prof. NIE Hong, the Vice President of NUAA, represented the host address and expressed welcome and gratitude to all the guests from home and abroad. He said the development of the technologies, environmental protection and the trade globalization require to continually improve the performance of products, and accurately select proper material and the manufacturing technology. As the revolutionary technology in casting development history, LFC technology has brought a brand-new change for the machine design and casting production. He hoped the conference would be beneficial to the development of Chinese LFC technololy and wished the symposium a complete success! Prof. YE Sheng-ping, the Executive Chairman of the conference and the Director of LFC Committee of FICMES, gave the opening address and read out the congratulations of F. J. Woestmann (Director of Germany LFC Technology Council), Wolfgang (General Manager of Storopack Hans Reichenecker Group), G Sedlmair Heiko (LFC project director of Teubert Maschinenbau GmbH), etc. Patrice Juton, the Sale Manager of Storopack Group, gave a speech on behalf of the conference delegates.

A Research on Investment Casting Technology of Ti Alloys

In this research, the materials and the compositions of the surface slurries were chosen by considering the characteristics of Ti investment casting. The effects of solid-liquid ratios on the properties of the slurry and the effects of baking temperatures on the flexural strength have also been investigated. Flawless shells having smooth inner surface were manufactured with proper technology. Ti and its alloys were melted and poured by water-cooled Cu crucible vacuum induction furnace. The qualities of the investment castings made accordingly were studied and analyzed.

New Argon Stopper Technology for Slab Casting

Argon addition into the casting channel reduces the amount of clogging on the refractory wall to allow long sequence casting of aluminium-killed steel grades.The key to minimum surface defects on the final product is to establish the optimum quantity by optimising the gas distribution below the stopper nose.This is achieved by new argon stopper technology which supports low gas quantities with homogeneous gas and bubble distributions to float non-metallic inclusions(NMI)in the continuous casting mould.

Two semi-solid die-casting production lines of Xuzhou Die- casting Technology Co., Ltd. officially put into operation

The two production lines for the first phase of the semi-solid die-casting high-end parts project were put into production in this October, and can monthly produce more than 30 thousand die casting parts.

Focusing on Technology and Services, Competing in China Die Casting Market

The Asia-Pacific Die Casting Industry Exhibition 2005, organized by Foundry Institution of Chinese Mechanical Engineering Society （FICMES）, was held in INTEX Shanghai, China on August 14-17, 2005. On August 16th, the journalists of CHINA FOUNDRY journal visited five exhibitors on the spot of exhibition. They are： Mr. Roland FINK, General manager of Frech （Shanghai） Die Casting Machine Co. Ltd.; Mr. Thomas STROBL, General manager of Buhler Equipment Engineering （Wuxi） Co. Ltd., Switzerland; Mr. WANG Tong, Manager of ABB Engineering （Shanghai） Co. Ltd.; Ms. Karen LUO, National Sales Manager-Die Casting, Chem-Trend （Shanghai） Trading Co. Ltd.; and Mr. David ZHOU, Sales Supervisor of Acheson, the National Starch ＆ Chemical （Shanghai） Company.