Investigation into the rapid compression of semi-solid alloy slugs

2001 ◽  
Vol 111 (1-3) ◽  
pp. 31-36 ◽  
Author(s):  
P. Kapranos ◽  
T.Y. Liu ◽  
H.V. Atkinson ◽  
D.H. Kirkwood
Keyword(s):  
Solid Alloy ◽  
Rapid Compression ◽  
Semi Solid

Rapid Compression Testing of Semi-Solid Alloy Slugs

2000 ◽  
Vol 329-330 ◽  
pp. 525-0 ◽  
Author(s):  
P. Kapranos ◽  
H.V. Atkinson ◽  
David H. Kirkwood
Keyword(s):  
Compression Testing ◽  
Solid Alloy ◽  
Rapid Compression ◽  
Semi Solid

Evaluation of Strip Rolling Directly from the Semi-Solid State

2006 ◽  
Vol 116-117 ◽  
pp. 433-436 ◽  
Author(s):  
Antonio de Pádua Lima Filho ◽  
Márcio Iuji Yamasaki
Keyword(s):  
Solid State ◽  
Cooling System ◽  
Solid Alloy ◽  
Strip Rolling ◽  
Tin Alloys ◽  
Cooling Slope ◽  
Quality Issue ◽  
Lower Roller ◽  
Semi Solid ◽  
Strip Quality

The aim of this work is to study the solidification conditions necessary to produce good quality/low defect metal alloy strip when thixorolling directly from the semi-solid state. To facilitate the study lead/tin alloys were chosen for their relatively low operating temperature. The objective is to extrapolate these findings to the higher temperature aluminium alloys. Three alloys (70%Pb- 30%Sn, 60%Pb-40%Sn, 50%Pb-50%wtSn) were used particularly to study the influence of the solidification interval. The equipment consists of a two roll mill arranged as an upper and lower roller, where both rollers are driven at a controlled speed. The lower roller is fed with semi solid alloy through a ceramic nozzle attached to the lower end of a cooling slope. Several types of nozzle and their position at the roller were tested. This produced different solidifications and consequently different finished strip. The alloys were first cast and then poured onto the cooling slope through a tundish in order to create a continuous laminar flow of slurry and uniformity of metal strip quality. The pouring was tested at different positions along the slope. The cooling slope was coated with colloidal graphite to promote a smooth slurry flow and avoid the problem of adherence and premature solidification. The metallic slurry not only cools along the slope but is also initially super-cooled to a mush by the lower roller whilst at room temperatures, thus enabling thixorolling. It was also found that the nozzle position could be adjusted to enable the upper roller to also contribute to the solidification of the metallic slurry. However the rollers and the cooling slope naturally heat up. Temperature distribution in these zones was analysed by means of three thermocouples positioned along the cooling slope and a fourth in the base of the semi solid pool within the nozzle. The objective being to design an optimum pouring and cooling system. The formed strip was cooled down to room temperature with a shower of water. Microstructures of the thixorolling process were analysed. The differences in solidification conditions resulted in differing qualities of finished strip and corresponding defect types, all of which are a serious quality issue for the rolled product.

Flow Behaviour of M2 Steel Alloy during Semi Solid Isothermal Rapid Compression

2012 ◽  
Vol 192-193 ◽  
pp. 311-316
Author(s):  
Farzad Hosseini Yekta ◽  
S.A. Sadough ◽  
Vahid Pouyafar ◽  
Amin Jabbari
Keyword(s):  
Flow Stress ◽  
Tool Steel ◽  
Constant Strain Rate ◽  
Special Kind ◽  
Holding Time ◽  
Plastic Behavior ◽  
Steel Alloy ◽  
Rapid Compression ◽  
Ram Speed ◽  
Semi Solid

The key to all semisolid processes is spherical and non-dendritic particles suspended in a liquid matrix. This special kind of microstructure causes the semisolid material to behave like a non-Newtonian fluid dependent on time and shear rate. Semi solid metal processing gives less shrinkage and porosity, non-macro segregation, lower flow stress, good formability and increased die life compared with conventional production methods. Therefore, semi solid processing introduces a good option for massive forming of high temperature alloys. Here, by partial remelting of M2 tool steel alloy under rapid compression test, deformation mechanism of steel alloy and its correlation to rheological properties were investigated. Flow stress for M2 tool steel alloy corresponding to solid fraction above 55% derived at constant strain rate and holding time. In order to investigate the parameter involved in this process, in the second stage of experiments the ram speed and holding time are variable. The analysis of the derived curves shows that the semisolid slurries exhibit a pseudo plastic behavior dependent on stain rate and temperature. The classical power law model used to describe the rheological and thixotropic dependence.

Thixoforming and Industrial Application of the Semi-Solid Alloy Al-6Si-2Mg

2006 ◽  
pp. 72-75 ◽  
Author(s):  
Li Jun Xie ◽  
Jun Xu ◽  
Bi Cheng Yang ◽  
Zhi Feng Zhang ◽  
Li Kai Shi
Keyword(s):  
Industrial Application ◽  
Solid Alloy ◽  
Semi Solid

Globule-Globule Interactions during Deformation in Semi-Solid Al-Cu Using Time-Resolved X-Ray Tomography

2012 ◽  
Vol 192-193 ◽  
pp. 179-184
Author(s):  
Kristina Maria Kareh ◽  
Peter D. Lee ◽  
Christopher M. Gourlay
Keyword(s):  
Solid Fraction ◽  
Three Dimensional ◽  
Solid Alloy ◽  
Three Dimensional Imaging ◽  
Time Resolved ◽  
X Ray ◽  
Analysis Techniques ◽  
Solid Deformation ◽  
Fundamental Understanding ◽  
Semi Solid

Optimising semi-solid processing and accurately modelling semi-solid deformation requires a fundamental understanding of the globule-scale mechanisms that cause the macroscopic rheological response. In this work, apparatus and analysis techniques are being developed for the time-resolved, three-dimensional imaging of semi-solid alloy deformation. This paper overviews synchrotron X-ray tomography results on globular Al-15wt%Cu deformed at 0.7 solid fraction using extrusion. The globule-globule interactions in response to load were quantified in terms of the response of individual globules with respect to globule translation, rotation, and deformation. The potential of time-resolved X-ray tomography in the study of semi-solid alloy deformation is then discussed.

Influence of Morphology on the Rheological Behavior of Semi-Solid A356 Aluminum Alloy

2006 ◽  
Vol 116-117 ◽  
pp. 601-605
Author(s):  
Heng Hua Zhang ◽  
Xian Nian Zhang ◽  
Guang Jie Shao ◽  
Luo Ping Xu ◽  
Yi Tao Yang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Solid State ◽  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Flow Behavior ◽  
A356 Alloy ◽  
Solid Alloy ◽  
A356 Aluminum Alloy ◽  
A356 Aluminum ◽  
Semi Solid

The morphology of semi-solid alloy is one of the key influence factors on the rheological behavior of slurry during die filling and the mechanical properties of formed parts. However, it is difficult to study such effect due to hard controlling of morphology in semi-solid state. In this paper, a self-developed Searle-type viscometer was used to determine the rheological behavior of A356 aluminum alloy in different morphology, which was refined with the salts mixture of K2TiF6 and KBF4. The results indicated that the flow behavior of refined A356 alloy in the semi-solid state possesses obviously thixotropic behavior under isothermal shearing condition with less time to reach steady state and lower steady apparent viscosity as compared to that of the A356 alloy. During continuous cooling at a constant shearing rate, the apparent viscosity of refined A356 slurry in the same solid fraction decreased with the content of Ti. It is shown from quantitative image analysis that the primary α-Al grain in the refined alloy evolves from dendrites to rosettes or sphericitys, and then tends to be rounder and finer in higher Ti content. The mechanism of the influence of morphology on rheological behavior was also discussed in this paper.

Simplified Rheocasting of Al-Si Alloys Sheared by Mechanical Stirring

2015 ◽  
Vol 651-653 ◽  
pp. 1545-1550 ◽  
Author(s):  
Alfredo Hernández ◽  
J. Federico Chávez ◽  
Raquel E. Hernández
Keyword(s):  
Stainless Steel ◽  
Solid State ◽  
Shear Rate ◽  
Microstructural Characterization ◽  
Dendritic Morphology ◽  
Solid Alloy ◽  
Mechanical Stirring ◽  
Simplified Method ◽  
Thixotropic Behavior ◽  
Semi Solid

A rheocasting prototype for the semi-solid processing of Al-Si alloys was designed and assembled at laboratory scale, this is the first attempt for the development of S2P equipment in Mexico. This work describes the simplified method of mechanical stirring and the calculation of the theoretical parameters for the operation of the experimental device in order to provide shear rate into the slurry by a stainless steel impeller inside a crucible made of hot work steel. Moreover, a vertical pressure die-rheocasting system it is applied with the semi-solid alloy flowing counter the position of the injector during the displacement of the crucible in order to fill the mold. New design is applied in this rheocasting equipment.The semi-solid state with thixotropic behavior is produced in the stirred AlSi7Mg alloy; this condition allows the non-dendritic morphology because the intensively stirring at the beginning of the solidification produces the trimming of dendrites, growing so the primary solid (α) in globular shape surrounded by eutectic microstructure. Preliminary microstructural characterization was performed.

Application of Radial Forging and Remelting Treatment to Prepare Semi-Solid Billet of AlMg0.7Si Alloy

2016 ◽  
Vol 256 ◽  
pp. 257-262 ◽  
Author(s):  
Yong Fei Wang ◽  
Sheng Dun Zhao ◽  
Chen Yang Zhang
Keyword(s):  
Grain Size ◽  
Partial Melting ◽  
Starting Material ◽  
Main Mechanism ◽  
Solid Alloy ◽  
Radial Forging ◽  
Area Reduction ◽  
Average Grain Size ◽  
Semi Solid ◽  
Deformation Recovery

Semi-solid AlMg0.7Si alloy was prepared by recrystallization and partial melting (RAP) method which including radial forging (RF) and remelting process. RF was carried out with different area reduction ratios (ARRs) to accumulate strains, effect of ARR and remelting time on microstructure was studied, mechanism of RAP preparing semi-solid AlMg0.7Si alloy was summarized. Results show that, compared with the large and irregular solid grains form remelting of starting material, solid grains of semi-solid alloy prepared by RAP are fine and globular, and the optimum microstructure can be obtained when alloy with 80% ARR is remelted at 630 °C for 10 min. With the increase of ARR, the solid grains are smaller and rounder. With the increase of remelting time, the average grain size is increased, and the spheroidization degree of solid grain is gradually improved. The main mechanism consists of pre-deformation, recovery and recrystallization, grains fragmentation, grains spheroidization and coarsening.

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