Separation of Non-Metallic Contaminants in Fluxless Melting and Refining of Magnesium Alloys

Hillis, James E.; Mercer, William E.

doi:10.4271/2000-01-1125

Cited by 5 publications

(5 citation statements)

References 5 publications

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“…The present paper discloses a fluxless refining method which is based on inert gas bubbling in order to float the non-metallic inclusions (NMI) to the melt surface [5,6,8]. This process requires the use of a protective gas atmosphere.…”

Section: Methodsmentioning

confidence: 99%

Recycling Technology Guidelines of MRI Die Casting Alloys

Gertsberg¹,

Yosef²,

Bronfín³

et al. 2008

SAE Technical Paper Series

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Creep-resistant HPDC alloys MRI153M and MRI230D are designated to replace HPDC aluminum alloys in the production of different automotive and non-automotive components. Due to the specific chemical compositions of the MRI alloys; they contain alkaline elements (Ca, Sr) with high affinity to Cl ions, fluxless technology must be used for recycling The present paper describes an technology which was developed for recycling MRI alloys. This technology combines simultaneous bubbling and stirring during batch processing. This operation is performed in order to improve metal cleanliness and reduce the process duration, thereby increasing its efficiency. The mechanical properties of recycled alloys were tested and compared with those of primary alloys. The influence of clean scrap dilution with primary material was also explored. The results obtained illustrate a moderate influence of scrap addition on mechanical properties. This effect should be considered for a wide range of die cast components production. The paper also presents guidelines for MRI alloys scrap handling and recycling.

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Section: Methodsmentioning

confidence: 99%

Recycling Technology Guidelines of MRI Die Casting Alloys

Gertsberg¹,

Yosef²,

Bronfín³

et al. 2008

SAE Technical Paper Series

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“…Preferably, a two-furnace system, Fig. 7, can be used [22]. When melting in one furnace and casting from a second furnace, excellent temperature stability can be achieved.…”

Section: Stoppagesmentioning

confidence: 99%

Metal Quality - From Ingot to Finished Product

Bakke

Andersen²,

Svalestuen³

et al. 2005

MSF

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Optimum performance of metal in the die casting shop in terms of metal loss, sludge generation, and high quality and consistency in mechanical properties of the die cast components are becoming increasingly important. In this context metal quality both from alloy producers’, die casters’ and end users’ perspectives is critical. The term metal quality can be defined to include 1) chemical composition, 2) inclusions and porosity inside the metal, 3) the surface appearance, and 4) consistency. This definition may apply to ingots as well as die cast parts. When the ingots are remelted and processed in the die casting shop, the effect of ingot surface quality and porosity on performance and properties is usually overshadowed by the quality of the processes in the die casting furnace. The paper discusses how the alloy gradually loses its pre-history. If the metal quality becomes inferior, housekeeping may become notoriously difficult, affecting important performance indicators such as up-time of operation and scrap rate. In partnership with the individual die casters, Hydro Magnesium offers assistance and audits to further improve the die caster’s performance and products.

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“…However, in any case it means that 99% or more of the oxides somehow has to be removed before the metal enters the casting machine. Although most of it probably can be skimmed off as dross (25) and a significant fraction settle out as sludge, it is very likely that some of it contaminate the metal to be cast. As a result, in-cell recycling imposes special requirements on the refining processes.…”

Section: Some Practical Consequencesmentioning

confidence: 99%

The Impact of Metal Cleanliness on Mechanical Properties of Die Cast Magnesium Alloy AM50

Bakke

Pettersen

Guldberg

et al. 2000

Magnesium Alloys and Their Applications

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IntroductionAs in-house and in-cell recycling is developing (1-5) one should expect metal cleanliness issues to be of paramount importance. However, until now metal cleanliness has to some extent been a neglected aspect as low cost solutions and smart logistics often have received the main focus (6-9). The effect of inclusions on mechanical properties is pronounced and well-known in steels. Properties such as ductility, fatigue, toughness and machinablilty are affected (10-12). Also within the aluminium industry inclusions are of great concern (10). Molten magnesium alloys oxidise more readily than any other metal cast or formed into components used for construction purposes. One might expect this to trig primary producers, end-users as well as researchers interest in quantifying the impact of inclusions on important mechanical properties. However, to our knowledge only a few papers have been published addressing this topic featuring die cast magnesium alloys (13-15). The essence of these papers is that in order to detect any influence of inclusions the content must be really high (at least 0.2 %). This might have lead to the opinion that metal cleanliness represents no obstacle to go ahead with in-house/in-cell recycling. Experimental Test materialStandard die cast test bars were produced from AM50 melts deliberately contaminated with oxide inclusions. AM50 was chosen because this is a highly ductile magnesium based alloy, possibly making a reduction in tensile properties more easily visible than for instance with the less ductile AZ91. Molten metal cleanliness was adjusted in part by introducing thin-walled scrap to a reference ingot melt, and in part by turning off the gas protection for short periods allowing the melt to burn. It was not possible to predict the metal cleanliness, it could only be determined retrospectively. Molten metal cleanliness was monitored with the Hydro Magnesium Inclusion Assessment Method (HMIAM) (16,17), distinguishing between oxide particles and oxide films. Samples were withdrawn both before and after casting of the melts. The melts were stirred manually just before casting in order to interrupt the refining caused by settling. The chemical composition of the melts was controlled by spectrographic analysis of permanent mould cast specimens. Die casting of test bars was done on the 3-cavity test bar die on the 200 ton Frech machine in Hydro Magnesium's foundry laboratory. Standard die cast test bars were made from 17 Magnesium Alloys and their Applications. Edited by K. U. Kainer.

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Separation of Non-Metallic Contaminants in Fluxless Melting and Refining of Magnesium Alloys

Cited by 5 publications

References 5 publications

Recycling Technology Guidelines of MRI Die Casting Alloys

Recycling Technology Guidelines of MRI Die Casting Alloys

Metal Quality - From Ingot to Finished Product

The Impact of Metal Cleanliness on Mechanical Properties of Die Cast Magnesium Alloy AM50

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