R-HPDC in South Africa

Curle, Ulyate Andries; Möller, Heinrich; Govender, Gonasagren

doi:10.4028/www.scientific.net/ssp.192-193.3

Cited by 16 publications

(25 citation statements)

References 50 publications

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“…This makes these alloys prone to hot tearing and segregation. The properties attained with the 2xx and 2xxx alloys were very similar to or better than the properties of commercial alloys [6]. The surface liquid segregation was observed in all 2xx and 2xxx alloys processed [14].…”

Section: Discussionmentioning

confidence: 57%

“…Even though SSM forming is more than 40 years old, the most common aluminium alloy researched and used in commercial application is the aluminium casting alloys based on the Al-Si alloy system. There has been a number of reported studies on the processing of high strength aluminium wrought and casting alloys in search of higher strengths [4,6,7]. Although SSM processing of these high strength alloys have been demonstrated successfully, there have been significant challenges in obtaining the combination of both strength and ductility for most of these alloys.…”

Section: Alloy Design For Ssm Formingmentioning

confidence: 99%

“…The CSIR has focussed its research activities in semi-solid forming on the processing of a wide range of aluminium cast and wrought alloys (Table 1) to demonstrate versatility of the CSIR-RCS and to develop a database of mechanical properties that is available for design engineers to use. The alloys were processed using the CSIR-RCS [6] and formed into simple sample geometries using a 130 ton high pressure die casting machine. The semi-solid processing of pure aluminium [11] as well as Al-Si eutectic binary alloy [12], with no freezing range, were processed and cast demonstrating the flexibility and versatility of the rheocasting process.…”

Section: Semi-solid Processing Of Aluminium Alloys Using the Csir Rhe...mentioning

confidence: 99%

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Alloy Design for Semi Solid Metal Forming

Govender¹,

Möller²,

Curle³

2014

MSF

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Semi-solid metal forming is more than 40 years old but its full potential to near net shape form high strength aluminium alloys has been realised only to a limited degree. Alloys developed for traditional manufacturing processes were initially used but it became apparent that alloys specific to SSM forming needed to be developed. The main alloy development criteria revolved around SSM processing temperature, solid fraction (fs) versus temperature sensitivity and age hardening potential. This methodology while sound does not fully address the unique processing behaviour of SSM forming. By its very nature SSM requires the controlled solidification of a part of the melt before forming. From basic solidification fundamentals this results in the enrichment of the remaining liquid with alloying elements. During the forming process segregation of liquid phase essentially produces a component with very different compositions in the regions where the liquid solidifies last. From recent work completed on a wide range of standard alloy systems it has become apparent that this segregation effect has a significant impact on aging behaviour and strength. Low melting point structures formed in the these regions result in localised melting in the grain boundary region and along areas of gross liquid segregation during solution heat treatment, contributing to the poor mechanical properties. Although this behaviour can be addressed using modified heat treatment, this cannot be applied to all current alloy systems. Alloy design for SSM forming must take these phenomena into account in order to develop and or specify aluminium alloys with acceptable mechanical properties.

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Section: Discussionmentioning

confidence: 57%

Section: Alloy Design For Ssm Formingmentioning

confidence: 99%

Section: Semi-solid Processing Of Aluminium Alloys Using the Csir Rhe...mentioning

confidence: 99%

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Alloy Design for Semi Solid Metal Forming

Govender¹,

Möller²,

Curle³

2014

MSF

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“…The induction heat serves to assist in controlling the cooling rate and agitates the melt to ensure that a slurry with a uniform temperature and globular microstructure is achieved. The processing flexibility was demonstrated by the range of alloys processed on the system as well as a unique achievement of demonstrating an SSM microstructure in pure aluminium (90,91). The processing flexibility was demonstrated by the range of alloys processed on the system as well as a unique achievement of demonstrating an SSM microstructure in pure aluminium (90,91).…”

Section: The Council For Scientific and Industrial Research Rheocastimentioning

confidence: 99%

Semisolid Processes

Govender

Möller

Damm

2014

Comprehensive Materials Processing

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“…The works were based on the existence of a time interval associated with solidification. The aim of the current work was to demonstrate that it is also possible to semi-solid metal R-HPDC commercial purity magnesium; supplementary to the CSIR R-HPDC process technology review by Curle et al [6].…”

Section: Introductionmentioning

confidence: 99%

Semi-Solid Casting of Pure Magnesium

Curle¹,

Wilkins²

2019

SSP

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Semi-solid processing works on the principal of a solidification temperature interval of a substance. The substance is heated to a temperature within this interval so that there exists a related solid-liquid fraction ratio. The substance with this phase structure is then shaped by a forging or casting process. It has been stated before that it is impossible to semi-solid process and cast pure metals or eutectic alloys due to their thermodynamic temperature invariance, meaning that there is no temperature interval. It was demonstrated recently that it is possible to semi-solid casting high purity aluminium (Curle UA, Möller H, Wilkins JD. Scripta Materialia 64 (2011) 479-482) and the Al-Si binary eutectic (Curle UA, Möller H, Wilkins JD. Materials Letters 65 (2011) 1469-1472). The working principal is that there exists a time interval during thermal arrest during which solidification takes place with a solid-liquid fraction ratio until all the liquid is consumed upon cooling. The aim with this work is to demonstrate that pure magnesium can also be rheo-high pressure die cast (R-HPDC) with the system developed at the CSIR in South Africa. Magnesium is notoriously difficult to cast due to the thermal properties of magnesium. The metal was poured into a cup, processed for about 6 seconds after which it was HPDC into a plate. The microstructure of the casting consists of a structure that was solid and a structure that was liquid during thermal arrest at the time of casting.

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R-HPDC in South Africa

Cited by 16 publications

References 50 publications

Alloy Design for Semi Solid Metal Forming

Alloy Design for Semi Solid Metal Forming

Semisolid Processes

Semi-Solid Casting of Pure Magnesium

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