special - Alu-web.de

More documents

Recommendations

Info

ALUMINIUM SMELTING INDUSTRY Optimisation of grain refinement in a range of casthouse aluminium alloys M. Bryant, MQP Fig. 1: Instrumentation used in the Opticast system MQP Ltd recently presented a paper at the 2013 TMS Conference in San Antonio, Texas, about optimising the grain refining process for aluminium alloys [1]. The article is based on that presentation, including some new information, and looks at • the optimisation technique used • a new powerful and consistent grain refiner, Optifine • and their combined effect on a range of aluminium alloys currently being produced at a casthouse involved in the study. Optimisation The Opticast system is proving to be an invaluable tool in carrying out assessment and control of grain refinement practice in industrial Fig. 2: Grain refiner curves for two master alloys with different efficiency casthouses by using data generated from sampling the melt in real time. Originally conceived by Lennart Backerud [2] and co-workers at Stockholm University, and since that time extensively developed, tested and refined, the Opticast technology is today being used for optimisation and control of grain refinement practice in casthouses worldwide. It produces rapid and reliable results so that accurate conclusions can be quickly made regarding implementation of optimised grain refining practice. Implementation of the Opticast system in the casthouse entails the following steps: calibration and sampling in casting furnace. Calibration involves establishing how a specific alloy responds to addition of fresh nuclei via the grain refining rod, in other words establishing the equations for the grain refinement curves as shown in Fig. 2. It shows a test carried out with two different batches of the same grain refiner in the same alloy melt. Obviously one batch is more efficient than the other and it follows that if both grain refiners are being used in a casthouse, the calibration must be done to handle any variations in the grain refiner efficiencies, that is © MQP a best and worst case scenario. This means that the calibration equation must be set up for the upper of the two curves and is for the lower one as well. The practical implication of this is that there is much to gain if the grain refiners used have a consistently high efficiency from batch to batch. Optifine Establishing that grain refiner variability is an important consideration factor in achieving a fully optimised practice has led to the development of a consistently powerful titanium boron master alloy grain refiner, Optifine. Optifine is produced via a special production route, which substantially optimises its nucleation potential. In standard TiBAl grain refiners only 1% of particles are active, and large boride particles and agglomerates lead to preferential formation of large grains whereas studies have shown that particles in the size range 1-3µ are optimum for nucleation. Optifine has been found to have over six times more active nuclei per ppm of boron Fig. 3: Microstructure of a standard TiBAl Fig. 4: Microstructure of Optifine 40 ALUMINIUM · 7-8/2013
SPECIAL ALUMINIUM SMELTING INDUSTRY than standard grain refiners and promotes fine equiaxed structures. Its efficiency as a grain refiner is at least twice, sometimes up to thirty times higher than standard Ti Bal refiners normally used. An independent metallographic study also shows that Optifine grain refiner has a very Fig. 5: Addition rates for standard TiBAl grain refiner (light blue-series 1) and Optifine (dark blue-series 2) for a range of AA alloys uniform microstructure (Fig. 4) without denuded zones or TiB2 clusters that can be seen in the typical standard Ti Bal grain refiner (Fig. 3). Casthouse trials at a remelt casthouse – Hulamin A trial programme carried out using the Opticast system in conjunction with Optifine grain refiner showed that adequate grain refinement could be achieved in all of the AA alloy groups that Hulamin produces with additions in the range 0.1 kg/t up to 0.24 kg/ t compared to the 0.34 kg/t up to 0.78 kg/t previously used with a standard TiBAl (Fig. 5). Expressed in percentages this means reductions of 56-81% in addition rates. Following these trials Optifine usage has been implemented in full production resulting in overall grain refiner usage being reduced to 45 tpy. Conclusion Optifine is a very potent grain refiner which allows reduction of addition rates to extremely low levels over a range of AA alloys. Since Optifine has a consistent high potency, and the grain refinement process can be closely monitored with the Opticast method, there is no risk for cracking of ingots and billets. Improvements in cast ingot quality can be expected due to consistent grain size, lower levels of borides, boride agglomerates and oxides introduced as a result of the substantial reduction in grain refiner addition as well as the uniform nature of the Optifine grain refiner microstructure. References [1] R. Vainik, J. Courtenay, B. Saglam: Optimisation of grain refinement, Light Metals, 2013 [2] L. Backerud and R. Vainik: Method for optimised aluminium grain refinement, Light Metals 2001, 951-954 Author Michael Bryant is marketing manager at MQP Ltd. BRUSHING AND GRINDING MACHINES SDV-Santioli AG/ DEMIS Wide Belt Processing Systems Industriestrasse 10 CH-8157 Dielsdorf Tel. +41 44 854 0908 Fax +41 44 854 0920 www.demis.ch Material width up to 3000 mm Material thickness up to 205 mm
Page 1 and 2: Official media partner of 17 th Ara
Page 3 and 4: EDITORIAL Volker Karow Chefredakteu
Page 5 and 6: CONTENTS in Betrieb genommen •
Page 7 and 8: NEW S IN BRIEF Amag aerospace plate
Page 9 and 10: NEW S IN BRIEF Mubadala and ICD est
Page 11 and 12: EVENTS Metef 2014 aiming to add new
Page 14: WIRTSCHAFT Produktionsdaten der deu
Page 17 and 18: WIRTSCHAFT mer des Ofens gefüllt,
Page 19 and 20: Looking ahead Mr Weiss, who resigne
Page 21 and 22: ECo N o M i CS The Chinese company
Page 23 and 24: unlikely to reach the levels that i
Page 26 and 27: ECo N o M i CS Cost item in million
Page 28 and 29: ECo N o M i CS 5. Advantages of the
Page 30 and 31: ALUMINIUM SMELTING INDUSTRY Primary
Page 32 and 33: ALUMINIUM SMELTING INDUSTRY Primary
Page 34 and 35: ALUMINIUM SMELTING INDUSTRY ergy it
Page 36 and 37: ALUMINIUM SMELTING INDUSTRY practic
Page 38 and 39: ALUMINIUMHÜTTENINDUSTRIE „Durode
Page 42 and 43: ALUMINIUM SMELTING INDUSTRY Achievi
Page 44 and 45: ALUMINIUMHÜTTENINDUSTRIE Die neue
Page 46 and 47: ALUMINIUMHÜTTENINDUSTRIE zu halten
Page 48 and 49: TECHNOLOGIE Der gesamte Schmelz- un
Page 50 and 51: TECHNOLOGIE Amag setzt durch die re
Page 52 and 53: TECHNOLOGIE Ein Blick hinter die Ku
Page 54 and 55: TECHNOLOGIE Inhaberfamilie Barten i
Page 56 and 57: TECHNOLOGIE Alumec setzt auf umwelt
Page 58 and 59: TECHNOLOGY Recycling of wrought alu
Page 60 and 61: TECHNOLOGY Fig. 2: Organisation of
Page 62 and 63: TECHNOLOGIE Präziser Schnitt aus A
Page 64 and 65: TECHNOLOGIE Ein Element dieser Ziel
Page 66 and 67: COMPANY NEWS WORLDWIDE and hence pr
Page 68 and 69: COMPANY NEWS WORLDWIDE by the Indon
Page 70 and 71: COMPANY NEWS WORLDWIDE Kobe Steel i
Page 72 and 73: PATENTE meet the smelter’s needs,
Page 74 and 75: PATENTE Verfahren zur Herstellung e
Page 76 and 77: LIEFERVERZEICHNIS 1 Smelting techno
Page 78 and 79: LIEFERVERZEICHNIS RIHS ENGINEERING
Page 80 and 81: LIEFERVERZEICHNIS • Packaging equ
Page 82 and 83: LIEFERVERZEICHNIS • Melting and h
Page 84 and 85: LIEFERVERZEICHNIS see Section handl
Page 86 and 87: LIEFERVERZEICHNIS • Rolling oil r
Page 88 and 89: LIEFERVERZEICHNIS 4.7 Casting machi
Page 90 and 91:
VORSCHAU / PREVIEW IM NÄCHSTEN HEF
Page 92:
Simply closer to your products. You
show all

special - Alu-web.de

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?