Special Issue "Net-Shape Die Casting of Semi-solid Alloys"

A special issue of Metals (ISSN 2075-4701).

Deadline for manuscript submissions: closed (31 December 2019).

Special Issue Editor

Dr. Plato Kapranos
E-Mail Website
Guest Editor
Department of Materials Science & Engineering, the University of Sheffield, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD, UK
Interests: metallic materials and composites; semi-solid metal forming; thixoforming; thixoforging; casting; welding; friction welding; additive manufacturing; property-structures relationships; heat treatments; non-destructive testing; engineering education and the development of personal and professional skills for doctoral students

Special Issue Information

Dear Colleagues,

Although shaping alloys in the semi-solid state (more commonly known as thixoforming) is a technology that has been around for good few decades now, both awareness of this technology and its industrial applications appear to have had a sketchy rate of success. However, if one looks beyond the various incarnations of this process they will soon discover that it is a very successful technology that has found applications in a variety of industries including the automotive, electronics and other consumer products.

In the last few years a new technology has entered the arena of near net-shape of alloys; Additive Manufacturing (AM). This 3D printing technology shows promise and even though it still proving itself, its potential is tremendous. Nevertheless, as all technologies, AM provides us with one more tool to deliver what customers require in competition with existing near net-shape technologies, such as casting and thixoforming.

To date, successful industrial applications of semi-solid processing are using mainly non-ferrous alloys such as aluminum, magnesium and zinc in direct competition with die-casting. On the research side, over the years, ferrous alloys, copper-based alloys, super alloys and composites have all been demonstrated as potential candidates but as yet they have not found their commercial niche.

Recent industrial developments around the world have once again brought semi-solid net-shape die casting back into play and although ‘prediction is difficult, especially about the future’; the signs about the future of this technology appear once again to be encouraging.

This Special Issue on “Net-Shape Die Casting of Semi-Solid Alloys” intends to bring you up to date with developments in this exciting manufacturing technology, current applications and possible future trends.

Dr. Plato Kapranos
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Net-Shape Die Casting
  • Semi-Solid Processing
  • Thixoforming
  • non-ferrous alloys
  • ferrous alloys

Published Papers (5 papers)

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Research

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Open AccessArticle
Thixoforming and Rheo-Die-Casting of A356/SiC Composite
Metals 2020, 10(2), 251; https://doi.org/10.3390/met10020251 - 13 Feb 2020
Abstract
This research investigated the rheo-die-casting process and the production of an A356/ silicon carbide (SiC) composite by a thixoforming. The composite contained 15 percent by weight SiC particles of around 15–37 µm in size as the reinforcing phase. The composite feedstock was produced [...] Read more.
This research investigated the rheo-die-casting process and the production of an A356/ silicon carbide (SiC) composite by a thixoforming. The composite contained 15 percent by weight SiC particles of around 15–37 µm in size as the reinforcing phase. The composite feedstock was produced by semi-solid stir-casting, where pretreated SiC powder was gradually added into the A356 alloy melt to form a continuously stirred slurry composite melt, which was then cast in a steel mold. For thixoforming, the feedstock was reheated to 583 °C (approximately 0.4 fraction liquid), and its viscosity was reduced with shear rate, implying that A356/SiC exhibits shear thinning or non-Newtonian behavior. This is caused by the characteristic billet structure obtained having relatively globular grains that accommodate the flow of the semisolid composite. In the rheo-die-casting process, the A356/SiC feedstock was re-melted at 610–615 °C (approximately 0.8–0.9 fraction liquid) prior to die-casting and the resulting slurry was injected into a die with injection speeds of 3 and 4 m/s and pressures of 11 and 12 MPa, respectively. Two work-pieces of 16 × 15.6 × 205 mm3 were produced in one shot, and the resulting samples were subjected to T6 solution treatment at 540 °C for 1 h, quenched, and aged at 135 °C for 12 h. The results show that both low speed and low pressure rheo-die-cast samples exhibit uneven filling at the end of the part, whilst both high pressure and high speed promote more uniform distribution of SiC particles throughout the part length. In the as-rheo-cast condition, the maximum hardness value is 82.16 HB, obtained from a rheo-cast sample cast at a speed of 4 m/s with a die pressure of 12 MPa. Full article
(This article belongs to the Special Issue Net-Shape Die Casting of Semi-solid Alloys)
Open AccessArticle
Near Solidus Forming (NSF): Semi-Solid Steel Forming at High Solid Content to Obtain As-Forged Properties
Metals 2020, 10(2), 198; https://doi.org/10.3390/met10020198 - 30 Jan 2020
Abstract
Near solidus forming (NSF) of steels is a novel process under the umbrella of semi-solid forming technologies midway between classical hot forging and semi-solid technologies. This article presents the work done at Mondragon Unibertsitatea to develop this technology and demonstrates the great potential [...] Read more.
Near solidus forming (NSF) of steels is a novel process under the umbrella of semi-solid forming technologies midway between classical hot forging and semi-solid technologies. This article presents the work done at Mondragon Unibertsitatea to develop this technology and demonstrates the great potential of the NSF process. The study proves the capability of the process to reduce raw material consumption by 20%, reduce forming loads from 2100 t to 300 t, and reduce forming steps from three to one, to obtain as-forged mechanical properties, as well as the excellent repeatability of the process. The work demonstrates that manufacturing commercial steel components in a single step using several off-the-shelf alloys is possible thanks to the flowing pattern of the material, which enables near-net shaping. In the first part of the article, a general overview of the semi-automated near solidus forming cell, together with a description of the NSF manufacturing trials, is provided, followed by the presentation and discussion of the results for the selected steel alloys. Full article
(This article belongs to the Special Issue Net-Shape Die Casting of Semi-solid Alloys)
Open AccessArticle
Cooling Behavior and Microstructure of Semisolid A201 Aluminum Alloy Prepared by the SEED Process
Metals 2019, 9(9), 922; https://doi.org/10.3390/met9090922 - 23 Aug 2019
Abstract
The biggest challenge in semisolid processing of high-performance aluminum alloys is the narrow temperature processing windows of these alloys, and as a result, the preparation of qualified semisolid slurries is very important. High solid fraction slurries of high-strength A201 alloy were prepared by [...] Read more.
The biggest challenge in semisolid processing of high-performance aluminum alloys is the narrow temperature processing windows of these alloys, and as a result, the preparation of qualified semisolid slurries is very important. High solid fraction slurries of high-strength A201 alloy were prepared by the Swirled Enthalpy Equilibration Device (SEED) process. The cooling behavior and microstructures of the A201 slurries produced by the standard, as well as a modified, SEED process were investigated. The results show that qualified A201 slurry can be produced by decreasing the pouring temperature and controlling the processing time in the SEED process. The modified SEED process significantly reduced the radial temperature gradient of the melt, due to the slow cooling rates involved, with the resulting slurries being more uniform, with more spherical microstructures, as compared to those produced by the standard SEED process. The formation of the nondendritic grain structure in the SEED process is attributed to the uniformly distributed large number of nuclei within the melt and the slow cooling of the melt in the containing crucible. Full article
(This article belongs to the Special Issue Net-Shape Die Casting of Semi-solid Alloys)
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Review

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Open AccessReview
Current Progress in Rheoforming of Wrought Aluminum Alloys: A Review
Metals 2020, 10(2), 238; https://doi.org/10.3390/met10020238 - 11 Feb 2020
Abstract
Semi-solid processing (SSP), including rheoforming and thixoforming, offers a promising opportunity to manufacture net-shaped parts with complex structure and excellent mechanical properties. Owing to its low cost and short process, rheoforming has been the subject of extensive study over the last two decades. [...] Read more.
Semi-solid processing (SSP), including rheoforming and thixoforming, offers a promising opportunity to manufacture net-shaped parts with complex structure and excellent mechanical properties. Owing to its low cost and short process, rheoforming has been the subject of extensive study over the last two decades. The interest in the rheoforming of wrought aluminum alloys is progressively growing among both the research and industrial communities. This review starts with reviewing the recent efforts and advances on preparation of semi-solid slurry of wrought Al alloys, followed by discussing the correlation between microstructure and performance of these alloys. Finally, special attention is paid in the industrial application and the future trends of rheoforming of wrought aluminum alloys. Full article
(This article belongs to the Special Issue Net-Shape Die Casting of Semi-solid Alloys)
Open AccessReview
Current State of Semi-Solid Net-Shape Die Casting
Metals 2019, 9(12), 1301; https://doi.org/10.3390/met9121301 - 02 Dec 2019
Abstract
Semi-solid processing of alloys is nearing the end of its fifth decade in existence. This promising manufacturing route has undergone a number of changes over the past five decades and apart from certain successful industrial applications, it appeared that it had become a [...] Read more.
Semi-solid processing of alloys is nearing the end of its fifth decade in existence. This promising manufacturing route has undergone a number of changes over the past five decades and apart from certain successful industrial applications, it appeared that it had become a niche technology with limited applications, notably in the automotive and consumer product markets. Nevertheless, despite the strong competition of traditional casting and in particular die-casting processes, and the emergence of Additive Manufacturing (AM), there seems to be a resurgence in demand for Net-Shape Die Casting of Semi-solid alloys as testified by the high numbers of delegates at the 15th SSM Conference at Shenzhen, China in September 2018. What follows is a brief review of the historical development of the process as well as more recent developments with an eye to future prospects. Full article
(This article belongs to the Special Issue Net-Shape Die Casting of Semi-solid Alloys)
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