Making Non-Dendritic Structure via Modified Cooling Slope Technique

The cooling slope technique has been developed in recent years, which controls the nucleation and growth of the primary grains during solidification to achieve fine and non-dendritic microstructures. In this study, A356 Al alloys were processed through a modified cooling slope technique to obtain fine, non-dendritic microstructures, in which the cooling rate of the cast crucible was controlled. Three process parameters, namely pouring temperature, inclined slope angle, and the cooling rate of the cast crucible, were varied during the processing. The cooling slope was water-cooled with a constant water flow rate. The solid fraction and the size distributions of the primary grains along the vertical and horizontal positions of the cast ingots were measured individually. The macro-segregation was examined in terms of the distribution of the solid fraction. The yields of the ingots were calculated for studying the efficiency of the cooling slope technique. The effects of the three process parameters on the microstructures, macro-segregation, and yields were studied by the Taguchi method.

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Formation of Globular Microstructure in A380 Aluminum Alloy by Cooling Slope Casting

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.264-265.272 ◽

2011 ◽

Vol 264-265 ◽

pp. 272-277 ◽

Cited By ~ 6

Author(s):

Nurşen Saklakoğlu ◽

S. Gencalp ◽

Şefika Kasman ◽

İ.E. Saklakoğlu

Keyword(s):

Aluminum Alloy ◽

Slope Angle ◽

Casting Process ◽

Solid Particles ◽

Inclined Plate ◽

Pouring Temperature ◽

Cooling Slope ◽

Semi Solid ◽

Cooling Slope Casting ◽

The Many

Thixoforming and related semi-solid processing (SSP) methods require thixotropic materials. One of the many SSP techniques is the cooling slope (CS) casting process, which is simple and has minimal equipment requirements, and which is able to produce feedstock materials for semisolid processing. When the feedstock is reheated to the semisolid temperature range, non-dendritic, spheroidal solid particles in a liquid matrix suitable for thixoforming are obtained. In this study, equipment for the CS technique was first established, and then the effects of the pouring temperature and inclined slope angle on the microstructures of A380 aluminum alloy (ISOAlSi8Cu3Fe) were studied. Optimum parameters for thixoforming experiments were selected, and it was found that the microstructure produced by the inclined plate depended on its angle and the pouring temperature.

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Effect of Primary α-Al Morphology in Slurry on Segregation during 357 Semi-Solid Die Casting

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.285.398 ◽

2019 ◽

Vol 285 ◽

pp. 398-402 ◽

Cited By ~ 1

Author(s):

Hong Zhang ◽

Da Quan Li ◽

Wen Ying Qu ◽

Fan Zhang ◽

Min Luo ◽

...

Keyword(s):

High Temperature ◽

Liquid Metal ◽

Solid Fraction ◽

Die Casting ◽

Dendritic Structure ◽

Solid Particles ◽

Pouring Temperature ◽

Seed Processing ◽

Semi Solid ◽

Solid Temperature

Controlling the morphology of the microstructure of the slurry is important during semi-solid die casting. For this project, semi-solid slugs were produced using the SEED (Swirled Enthalpy Equilibrium Device) process, where a fully liquid metal is poured into a steel crucible and cooled into the semi-solid temperature range, and the crucible and slurry are then swirled and cooled to the appropriate temperature (and solid fraction) for semi-solid casting. The pouring temperature of the melt into the crucible during SEED processing has been shown to influence the morphology and size of the aluminum solid particles within the slurry, which can influence the distribution and segregation of the solid particles during die casting. In this study, a specially-designed die with a serpentine-shaped flow channel has been used to study the distribution of the solid particles during semi-solid die casting. The experimental results show that a dendritic structure is formed when the liquid is poured from a high temperature, while a globular semi-solid morphology is more easily formed when poured from a low superheat. The current results also show that a dendritic structure leads to severe segregation during die casting.

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Prepartion of Semisolid AM60 Alloy by Novel Self-Inoculation Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3804 ◽

2011 ◽

Vol 189-193 ◽

pp. 3804-3809 ◽

Cited By ~ 1

Author(s):

Yuan Dong Li ◽

Bo Xing ◽

Ying Ma ◽

Ti Jun Chen ◽

Yuan Hao

Keyword(s):

Slope Angle ◽

Dendritic Structure ◽

Primary Phase ◽

Chemical Pollution ◽

Cooling Channel ◽

Dendritic Microstructure ◽

Pouring Temperature ◽

Inoculation Method ◽

Semi Solid ◽

Slurry Preparation

A research focus on semi-solid metal processing is the preparation of semi-solid slurry with non-dendritic microstructure. During the past several decades, people tended to obtain the non-dendritic structure by stirring melt of alloy which downs to the semi-solid temperature range, such as mechanical stirring and electromagnetic stirring; In recent years, with the technological innovation of semi-solid slurry preparation turned to be more convenient and efficient, most of these processes are based on the control of nucleation and growth process of primary phase during solidification, such as NRC, SSR, SLC, SEED, and CRP. In this paper, a novel process, named as “Self-Inoculation Method (SIM)”, has been proposed for semi-solid slurry preparation. The process involves self-inoculants addition to the melt, and then pouring the melt to mould through a multi-stream mixed cooling channel. The melt was avoided chemical pollution due to the particles of self-inoculants from the same composition as the melt. The semi-solid billets of AM60 alloy with non-dendritic structure were prepared by SIM. The effects of process parameters on the microstructure and the mechanism on refinement of alloy were investigated. The results indicate that pouring temperature, addition amount of self-inoculants and slope angle of the cooling channel are key factors for SIM process. The optimized parameters for the billet preparation of AM60 alloy are obtained: pouring temperature is at 680°C~700°C；addition of self-inoculants are between 5%~7% (mass fraction)；slope angle of the cooling channel is at 30°~45°. The heterogeneous nucleation was enhanced as the addition of self-inoculants; the formation of chill crystal and the fragmentation of dendrites because of cooling and shearing of the cooling channel, resulting in the increase of grains density and a small grain size.

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Comparison of Phase Characteristics and Residual Stresses in Ti-6Al-4V Alloy Manufactured by Laser Powder Bed Fusion (L-PBF) and Electron Beam Powder Bed Fusion (EB-PBF) Techniques

Crystals ◽

10.3390/cryst11070796 ◽

2021 ◽

Vol 11 (7) ◽

pp. 796

Author(s):

Aya Takase ◽

Takuya Ishimoto ◽

Naotaka Morita ◽

Naoko Ikeo ◽

Takayoshi Nakano

Keyword(s):

Electron Beam ◽

Residual Stresses ◽

Cooling Rate ◽

Process Parameters ◽

Phase Evolution ◽

Powder Bed Fusion ◽

Laser Powder Bed Fusion ◽

Solidification Temperature ◽

Powder Bed ◽

Β Phase

Ti-6Al-4V alloy fabricated by laser powder bed fusion (L-PBF) and electron beam powder bed fusion (EB-PBF) techniques have been studied for applications ranging from medicine to aviation. The fabrication technique is often selected based on the part size and fabrication speed, while less attention is paid to the differences in the physicochemical properties. Especially, the relationship between the evolution of α, α’, and β phases in as-grown parts and the fabrication techniques is unclear. This work systematically and quantitatively investigates how L-PBF and EB-PBF and their process parameters affect the phase evolution of Ti-6Al-4V and residual stresses in the final parts. This is the first report demonstrating the correlations among measured parameters, indicating the lattice strain reduces, and c/a increases, shifting from an α’ to α+β or α structure as the crystallite size of the α or α’ phase increases. The experimental results combined with heat-transfer simulation indicate the cooling rate near the β transus temperature dictates the resulting phase characteristics, whereas the residual stress depends on the cooling rate immediately below the solidification temperature. This study provides new insights into the previously unknown differences in the α, α’, and β phase evolution between L-PBF and EB-PBF and their process parameters.

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Effect of Cooling Slope Process Parameters on Non-dendritic Feedstock Production: A Comprehensive Review

Journal of The Institution of Engineers (India) Series C ◽

10.1007/s40032-021-00693-9 ◽

2021 ◽

Author(s):

Rishitosh Ranjan ◽

B. Surekha ◽

Prakash Ghose

Keyword(s):

Process Parameters ◽

Comprehensive Review ◽

Cooling Slope ◽

Feedstock Production ◽

Slope Process

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Preparation of Semisolid A356 Alloy by a Cooling Slope Processing

Materials Science Forum ◽

10.4028/www.scientific.net/msf.675-677.767 ◽

2011 ◽

Vol 675-677 ◽

pp. 767-770 ◽

Cited By ~ 3

Author(s):

Jun Xu ◽

Tong Min Wang ◽

Zong Ning Chen ◽

Jing Zhu ◽

Zhi Qiang Cao ◽

...

Keyword(s):

A356 Alloy ◽

A356 Aluminum Alloy ◽

Forming Process ◽

Pouring Temperature ◽

Cooling Slope ◽

Optimum Parameters ◽

Grain Structures ◽

Semisolid Forming ◽

Size And Morphology ◽

A356 Aluminum

In order to obtain the non-dendritic feedstock for the semisolid forming process, a cooling slope processing was used. In this work, the effects of the angle, length of cooling slope and pouring temperature on the microstructure of A356 aluminum alloy were investigated. It showed that these parameters affect the size and morphology of α-Al phase to some extent. The results indicate that a pouring temperature of 650°C and a cooling slope with 45° in angle and 50 cm in length are the optimum parameters for preparing fine and globular grain structures. To eliminate the solidification shell formed in the surface of cooling slope, a nitride dope was coated on the surface of the cooling slope.

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Modelling of Thermal Quantities for Quick Process Assessment and Process Capability Space Refinement at an Early Design Phase During Laser Welding

10.21203/rs.3.rs-1129775/v1 ◽

2021 ◽

Author(s):

Anand Mohan ◽

Dariusz Ceglarek ◽

Michael Auinger

Keyword(s):

Heat Transfer ◽

Laser Welding ◽

Cooling Rate ◽

Process Parameters ◽

Thermal Cycle ◽

Welding Process ◽

Process Capability ◽

Peak Temperature ◽

Transfer Model ◽

Process Assessment

Abstract This research aims at understanding the impact of welding process parameters and beam oscillation on the weld thermal cycle during laser welding. A three-dimensional heat transfer model is developed to simulate the welding process, based on the finite element (FE) method. The calculated thermal cycle and weld morphology are in good agreement with experimental results from literature. By utilizing the developed heat transfer model, the effect of welding process parameters such as heat source power, welding speed, radius of oscillation, and frequency of oscillation on the intermediate performance indicators (IPIs) such as peak temperature, heat-affected zone volume (HAZ), and cooling rate is quantified. Parametric contour maps for peak temperature, HAZ volume, and cooling rate are developed for the estimation of the process capability space. An integrated approach for rapid process assessment, process capability space refinement, based on IPIs is proposed. The process capability space will guide the identification of the initial welding process parameters window and help in reducing the number of experiments required by refining the feasible region of process parameters based on the interactions with the IPIs. Here, the peak temperature indicates the mode of welding performed while the HAZ volume and cooling rate are weld quality indicators. The regression relationship between the welding process parameters and the IPIs is established for quick estimation of IPIs to replace time-consuming numerical simulations. The proposed approach provides a unique ability to simulate the laser welding process and provides a robust range of process parameters.

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Using ProCAST to Study the Effects of SEED Process Parameters on the Radial Temperature Distribution in Semi-Solid Slugs

Materials Science Forum ◽

10.4028/www.scientific.net/msf.993.1004 ◽

2020 ◽

Vol 993 ◽

pp. 1004-1010

Author(s):

Min Luo ◽

Da Quan Li ◽

Wen Ying Qu ◽

Stephen P. Midson ◽

Qiang Zhu ◽

...

Keyword(s):

Heat Transfer ◽

Heat Transfer Coefficient ◽

Temperature Distribution ◽

Transfer Coefficient ◽

Solid Fraction ◽

Process Parameters ◽

Radial Temperature ◽

Fraction Distribution ◽

Semi Solid ◽

The Heat Transfer Coefficient

The SEED (Swirled Enthalpy Equilibrium Device) process was used to produce semi-solid slurries. One of the factors that controls whether or not a slug can be used to produce high quality castings is the solid fraction distribution within the slug, and the solid fraction distribution is strongly dependent upon the temperature distribution. In this study, a model has been developed using ProCAST to investigate the relationship between process parameters and the temperature distribution within slugs. The parameters examined included the heat transfer coefficient between the crucible and slug, the heat transfer coefficient between the crucible and air, the slug diameter, and the initial melt temperature (pouring temperature). It was found that the most important parameters controlling the temperature distribution within slugs were the crucible size and the heat transfer coefficient between crucible and air. Adjustment of other parameters had little influence on the temperature distribution. Processing parameters will be discussed in order to allow the SEED process to be used for the production of large diameter slugs (>100 mm), and for narrow freezing range (0.3<fs<0.5, fs is fraction solid) alloys such as 6063.

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