scholarly journals Influence of Microstructural Inhomogeneity on Fracture Behaviour in SSM-HPDC Al-Si-Cu-Fe Component with Low Si Content

2014 ◽  
Vol 217-218 ◽  
pp. 67-74 ◽  
Author(s):  
Mostafa Payandeh ◽  
Anders E.W. Jarfors ◽  
Magnus Wessen
Keyword(s):  
Surface Segregation ◽  
Fracture Behaviour ◽  
Tensile Specimen ◽  
Cast Material ◽  
Near Surface ◽  
Die Cast ◽  
Microstructural Inhomogeneity ◽  
Trapped Gas ◽  
Semi Solid ◽  
Si Content

In the current paper, a low-Si containing aluminium alloy (1.4-2.2% Si) was used to fabricate a complex shape telecom component using Semi-Solid High-Pressure Die Cast (SSM-HPDC), process. Microstructure and fracture characteristics were investigated. The cast material exhibited microstructural inhomogeneity, in particular macrosegregation in the form of liquid surface segregation bands in addition to sub-surface pore bands and gross centre porosity. Tensile specimen were taken from the cast components. Elongation and microstructural inhomogeneity were investigated and correlated. Fracture surfaces of the tensile specimen were examined under scanning electron microscope (SEM). The study showed that both near surface liquid segregation bands and subsurface porosity strongly affected the fracture behaviour. Dominant for loss of ductility were gross centre porosity. This centre porosity was found to be a combination of trapped gas and insufficient, irregular feeding patterns.

scholarly journals Filling, Feeding and Defect Formation of Thick-Walled AlSi7Mg0.3 Semi-Solid Castings

2016 ◽  
Vol 256 ◽  
pp. 222-227 ◽  
Author(s):  
Jorge Santos ◽  
Anders E.W. Jarfors ◽  
Arne K. Dahle
Keyword(s):  
High Pressure ◽  
Cross Sections ◽  
Surface Segregation ◽  
Defect Formation ◽  
Shear Bands ◽  
Casting Machine ◽  
Shrinkage Porosity ◽  
Cast Material ◽  
Lower Porosity ◽  
Semi Solid

Aluminium semi-solid castings have gained increased attention due to their superior mechanical properties, lower porosity compared to conventional high pressure die cast material. These characteristics suggests that semi-solid casting should be suitable to produce thick-walled structural components, yet most successful applications of semisolid casting have been for thin-walled components. There is a lack of understanding on filling and feeding related defect formation for semi-solid castings with thick-walled cross-sections. In the current study an AlSi7Mg0.3 aluminium alloy was used to produce semi-solid castings with a wall thickness of 10mm using a Vertical High Pressure Die Casting machine. The RheoMetalTM process was used for slurry preparation. The primary solid α-Al fraction in the slurry was varied together with die temperature. The evaluation of the filling related events was made through interrupted shots, stopping the plunger at different positions. Microscopy of full castings and interrupted test samples were performed identifying the presence of surface segregation layer, shear bands, gas entrapment, shrinkage porosity as well as burst feeding.

The Mechanical Properties of Rheo-High Pressure Die Cast Al-Mg-Si-(Cu) 6xxx Series Alloys

2014 ◽  
Vol 217-218 ◽  
pp. 61-66 ◽  
Author(s):  
Heinrich Möller ◽  
Pfarelo Daswa ◽  
Gonasagren Govender
Keyword(s):  
Mechanical Properties ◽  
High Pressure ◽  
Hot Tearing ◽  
Limited Information ◽  
Die Cast ◽  
Near Net Shape ◽  
Alloy Castings ◽  
Semi Solid ◽  
Si Content ◽  
6Xxx Series

Near-net shape casting of wrought aluminium alloys has proven to be difficult due to a tendency towards hot tearing during cooling. Rheo-high pressure die casting (R-HPDC), has been shown to be an effective method of producing near-net shape wrought aluminium alloy castings. Limited information is available regarding the mechanical properties of age-hardenable wrought Al-castings produced by semi-solid metal forming. The purpose of this study is to investigate the effects of chemical composition and natural pre-ageing on the hardness and mechanical properties of rheo-HPDC 6xxx series Al-Mg-Si-(Cu) alloys in the T6 temper condition. The effects of the addition of Cu, as well as the (Mg+Si) content and Mg:Si ratio of the alloys are quantified. Alloys that are included are Cu-free 6004 and 6082, as well as Cu-containing 6013, 6111 and 6066. It is shown that the addition of Cu and excess Si result in higher hardness and strength. Natural pre-ageing has a significant effect (positive for 6004 and negative for the others) on the T6 properties. Good strength values can be achieved, but ductility is dependent on factors such as hot tearing during casting and incipient melting during solution heat treatment.

Near-Surface Aggregation of Sn In Heavily Sn-Doped GaAs Films Grown By Molecular Beam Epitaxy

1985 ◽  
Vol 43 ◽  
pp. 368-369
Author(s):  
S. H. Chen
Keyword(s):  
Molecular Beam Epitaxy ◽  
Cross Section ◽  
Electron Spectroscopy ◽  
Molecular Beam ◽  
Surface Segregation ◽  
Secondary Ion Mass Spectrometry ◽  
Specimen Preparation ◽  
Near Surface ◽  
Gaas Films ◽  
Secondary Ion

Sn has been used extensively as an n-type dopant in GaAs grown by molecular-beam epitaxy (MBE). The surface accumulation of Sn during the growth of Sn-doped GaAs has been observed by several investigators. It is still not clear whether the accumulation of Sn is a kinetically hindered process, as proposed first by Wood and Joyce, or surface segregation due to thermodynamic factors. The proposed donor-incorporation mechanisms were based on experimental results from such techniques as secondary ion mass spectrometry, Auger electron spectroscopy, and C-V measurements. In the present study, electron microscopy was used in combination with cross-section specimen preparation. The information on the morphology and microstructure of the surface accumulation can be obtained in a fine scale and may confirm several suggestions from indirect experimental evidence in the previous studies.

scholarly journals Tribological Characteristics of the Magnesium Matrix-Glassy Carbon Particles Composite Manufactured by Different Casting Methods

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Anita Olszówka-Myalska ◽  
Jerzy Myalski ◽  
Bartosz Hekner
Keyword(s):  
Glassy Carbon ◽  
Sliding Friction ◽  
Particulate Composite ◽  
Magnesium Matrix ◽  
Cast Material ◽  
Carbon Particles ◽  
Die Cast ◽  
Pin On Disc ◽  
Worn Surface ◽  
Gravity Cast

A particulate composite with a magnesium matrix (Mg3Al) and glassy carbon particles (GCp) obtained under industrial conditions from a gravity cast and pressure die cast suspension was examined. The influence of the casting procedure on the microstructure and mechanical properties was revealed. Sliding friction tests by the pin-on-disc method for different loads (2.3, 5, and 9.3 N) and speeds (0.06, 0.09, and 0.14 m/s) were performed. Regardless of the technology, the sliding friction coefficient’s value strongly depended on the load and speed. Its value was changing (0.35–0.13) and was usually higher for the pressure die cast material, yet the wear resistance of the composite processed in that way was considerably better compared with the gravity cast. The results of the worn surface observation by SEM with EDS showed an influence of the initial Mg3Al-GCp composite’s microstructure on the processes of its wear.

Bending Strength and Fracture Behaviour of Metal-Ceramic Interpenetrating Phase Composites Manufactured by Using Semi-Solid Forming Technology

2022 ◽  
Vol 327 ◽  
pp. 111-116
Author(s):  
Laura Schomer ◽  
Kim Rouven Riedmüller ◽  
Mathias Liewald
Keyword(s):  
Bending Strength ◽  
Fracture Behaviour ◽  
Structural Characteristics ◽  
Process Window ◽  
Metallic Material ◽  
Forming Technology ◽  
Metal Ceramic ◽  
Semi Solid ◽  
The Impact ◽  
Interpenetrating Phase Composites

Interpenetrating Phase Composites (IPC) belong to a special category of composite materials, offering great potential in terms of material properties due to the continuous volume structure of both composite components. While manufacturing of metal-ceramic IPC via existing casting and infiltration processes leads to structural deficits, semi-solid forming represents a promising technology for producing IPC components without such defects. Thereby, a solid open pore body made of ceramic is infiltrated with a metallic material in the semi-solid state. Good structural characteristics of the microstructure as the integrity of the open-pore bodies after infiltration and an almost none residual porosity within the composites have already been proven for this manufacturing route within a certain process window. On this basis, the following paper focuses on the mechanical properties such as bending strength of metal-ceramic IPC produced by using semi-solid forming technology. Thereby, the impact of the significant process parameters on these properties is analysed within a suitable process window. Furthermore, a fractographic analysis is carried out by observing and interpreting the fracture behaviour during these tests and the fracture surface thereafter.

scholarly journals Fluidity Investigation of Pure Al and Al-Si Alloys

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5372
Author(s):  
Toshio Haga ◽  
Shinjiro Imamura ◽  
Hiroshi Fuse
Keyword(s):  
Heat Transfer ◽  
Melt Spinning ◽  
Pure Aluminum ◽  
Injection Speed ◽  
Roll Casting ◽  
Die Cast ◽  
Flow Length ◽  
Cast Machine ◽  
Die Temperature ◽  
Si Content

Fluidity tests of pure aluminum 1070 and Al-Si alloys with Si contents of up to 25% were conducted using a die cast machine equipped with a spiral die. The effects of the channel gap, die temperature, and injection speed on the fluidity were investigated. When the channel gap was small (0.5 mm), the flow length of the 1070 was minimized, and the fluidity increased monotonically at a gradual rate with increasing Si content. In contrast, larger gaps yielded convex fluidity–Si content curves. Additionally, heating the die had less of an influence on the fluidity of the 1070 than on that of the Al-Si alloy. These results are discussed in the context of the peeling of the solidification layer from the die based on the thicknesses of foils and strips cast by melt spinning and roll casting, respectively. At lower Si contents, heat shrinkage was greater and the latent heat was lower. When the heat shrinkage was greater, the solidification layer began to peel earlier, and the heat transfer between the solidification layer and the die became smaller. As a result, the fluidity of the 1070 was greatest when the channel gap was 0.8 mm.

Microstructure Control and Structure Analysis in the Semi-Solid State of Different Feedstock Materials for the Bearing Steel 100Cr6

2006 ◽  
Vol 116-117 ◽  
pp. 177-180 ◽  
Author(s):  
Wolfgang Püttgen ◽  
Wolfgang Bleck ◽  
B. Hallstedt ◽  
Peter J. Uggowitzer
Keyword(s):  
Solid State ◽  
Grain Growth ◽  
Dynamic Mechanical Properties ◽  
Negative Influence ◽  
Bearing Steel ◽  
Cast Material ◽  
Fine Grained ◽  
Semi Solid ◽  
Hot Rolled ◽  
Feedstock Material

The bearing steel 100Cr6 in the forged and hardened condition is of great importance in industrial use. Escaping the geometry restrictions of conventional forging, the application of semi-solid metalworking (SSM) offers significantly increased design freedom. Using conventionally available rolled feedstock material with carbide banding, however, results in a higher segregation tendency during thixoforging, and thus special attention was paid to the feedstock’s “quality”. To achieve a fine-grained, globular microstructure in the semi-solid state, castings with and without the addition of 100 ppm titanium were compared with the hot rolled material. With its inherent nitrogen Ti forms TiN particles, which reduce grain-growth in austenite. The results indicate that TiN precipitates strongly affect grain growth during solid state processing, but the grain size in the semi-solid state can only be influenced for short process times. Generally the cast feedstock materials possess smaller globulites in the semi-solid state compared to forgings, so that a reduction of the sponge effect and a minimization of the segregation in produced components are expected. Since the cast material already showed a fine-grained, globulitic microstructure, the use of TiN is not recommended because of the possible negative influence of TiN on the dynamic mechanical properties.

EN AC-46500 Injected by Semi-Solid Rheocasting

2008 ◽  
Vol 141-143 ◽  
pp. 283-288 ◽  
Author(s):  
Manel Campillo ◽  
Maite T. Baile ◽  
Sergi Menargues ◽  
Antonio Forn
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
High Pressure ◽  
Structural Integrity ◽  
Tensile Tests ◽  
Simulation Software ◽  
Industrial Plant ◽  
Forming Process ◽  
Die Cast ◽  
Semi Solid

EN AC-46500 aluminium components are formed by Semi-Solid Rheocasting (SSR) in an industrial plant using a 700 tons high pressure machine. The dies wear was designed by the PLCO model of the ProCast simulation software. The components have had a good structural integrity and the mechanical properties after T6 treatment have been equivalent to that obtained by the same alloy by die cast. The present work describes the SSR forming process, the resulting microstructure as well as the optimization of the ageing heat treatment by hardness evolution. The results of the tensile tests make these clear.

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