Hot Tearing Susceptibility and Fluidity of Semi-Solid Gravity Cast Al-Cu Alloy

2006 ◽  
Vol 116-117 ◽  
pp. 76-79 ◽  
Author(s):  
J. Wannasin ◽  
David Schwam ◽  
J.A. Yurko ◽  
C. Rohloff ◽  
G. Woycik
Keyword(s):  
Liquid State ◽  
Copper Alloys ◽  
High Strength ◽  
Hot Tearing ◽  
Gravity Casting ◽  
Aluminum Copper Alloys ◽  
Semi Solid ◽  
High Superheat ◽  
Constrained Rod Casting ◽  
Hot Tearing Susceptibility

Aluminum-copper alloys offer both high strength and excellent ductility suitable for a number of automotive applications to reduce vehicle weight; however, the alloys are difficult to cast because of their tendency for hot tearing. In this work, semi-solid gravity casting of an aluminum-copper alloy, B206, was conducted in constrained rod casting molds to study the feasibility of using the process to reduce or eliminate hot tearing. To demonstrate the feasibility of gravity casting of the metal slurries, a fluidity test was also conducted. Results show that the hot tearing susceptibility of the aluminum-copper B206 alloy cast in semi-solid state is lower than those cast in liquid state with high superheat temperatures. The grain size of the semi-solid cast Al-Cu samples appears to be finer than those cast in liquid state with high superheat temperatures. In addition, the metal slurries had sufficient fluidity to fill the molds even with low gravity pressures. The results suggest that semi-solid gravity casting is a feasible process to help reduce hot tearing.

Slurry Preparation and Hot Tearing Susceptibility of A201 Aluminum Alloy in Rheological Die Casting

2019 ◽  
Vol 285 ◽  
pp. 311-317 ◽  
Author(s):  
Jun Zhen Gao ◽  
Qiang Zhu ◽  
Da Quan Li ◽  
Xiao Gang Hu ◽  
Min Luo ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Die Casting ◽  
Mold Temperature ◽  
Hot Tearing ◽  
Cast Aluminum Alloy ◽  
Cast Aluminum ◽  
Intensification Pressure ◽  
Semi Solid ◽  
Index Value ◽  
Hot Tearing Susceptibility

A201 alloy is the strongest cast aluminum alloy, but it is considered one of the most difficult aluminum alloys to cast due to its susceptibility to hot tearing during solidification. Semi-solid casting, which characterizes fine near-globular or non-dendritic grains and relatively narrow solidification range, is potential to reduce hot cracking tendency of alloys. In this present work, semi-solid slurries of A201 alloy were prepared using Swirled Enthalpy Equilibrium Device (SEED) technique and then injected into a self-designed high pressure hot tearing mold. The microstructures of A201 semi-solid slurries with different pouring temperatures were examined. Effects of different casting pressures on the hot tearing sensitivity of A201 have been investigated. This study finds that SEED is capable of producing satisfying A201 semi-solid slurries. Lower pouring temperatures produce A201 semi-solid slurries with finer and rounder grains as well as more uniform microstructure distribution. Increasing the intensification pressure significantly decreases the hot treating tendency of A201 alloy. When the pressure reaches to 90 MPa and the mold temperature of about 250 °C, the hot tearing susceptibility (HTS) index value is nearly zero, which means almost no surface cracks are found in the semi-solid A201 die casting parts.

Casting and Heat Treatment of Turbocharger Impellers Thixocast from Alloy 201

2012 ◽  
Vol 192-193 ◽  
pp. 556-561 ◽  
Author(s):  
Qiang Zhu ◽  
Stephen Midson ◽  
Chang Wei Ming ◽  
Helen V. Atkinson
Keyword(s):  
Heat Treatment ◽  
High Strength ◽  
Heat Treatment Condition ◽  
Hot Tearing ◽  
Alloy Casting ◽  
Heat Treated ◽  
Before And After ◽  
Optimum Heat ◽  
Semi Solid ◽  
Optimum Heat Treatment

Commercial semi-solid cast impellers are produced from Al-Si-Cu alloys heat treated to the T6 temper. The study described in this paper involved the identification of casting and heat treatment parameters to produce semi-solid processed turbocharger impellers from a silicon-free, higher strength 201 alloy. Casting parameters were identified which minimized hot tearing in the alloy 201 impellers. A series of heat treatment studies were performed to determine optimum heat treatment parameters. The T71 temper was identified as the preferred heat treatment condition to produce high strength as well as superior elongation. The results from mechanical property measurements conducted on the T71 heat treated impellers are reported. Optical and scanning electron microscopy (SEM) were also used to characterize the microstructure of alloy 201 impellers before and after heat treatment, and representative microstructures are presented.

Metallurgical and Foundry Parameters for the SSM Forming of High Strength Aluminium-Zinc-Magnesium-Copper (7075) Alloy

2009 ◽  
Vol 618-619 ◽  
pp. 611-614 ◽  
Author(s):  
L.G. Juganan ◽  
Gonasagren Govender ◽  
A.F. Mulaba Bafubiandi
Keyword(s):  
Melting Furnace ◽  
Optical Emission ◽  
High Strength ◽  
Hot Tearing ◽  
Compositional Variation ◽  
Limited Information ◽  
Casting Technique ◽  
Compositional Variations ◽  
Semi Solid ◽  
7075 Alloy

Aluminium-Zinc-Magnesium-Copper, 7075, alloy offers both high strength (comparable with those of alloy steels) and very good ductility which makes this alloy group suitable for many automotive, aerospace and defence applications, however the alloys are difficult to cast because of their tendency for Hot Tearing. The Semi-Solid Metalforming (SSM) casting technique allows for near net shape casting using High-Pressure Diecasting (HPDC). The lower forming temperature reduces the problem of Hot Tearing. The CSIR has developed a rheocasting process which prepares semi-solid slurries from molten metal which can then be formed using HPDC. Since 7075 is a wrought alloy there is limited information on the foundry practice for this alloy. The aim of this study is to determine the foundry practice for 7075 aluminium alloy. Melting trials and optical emission spectroscopy on, AA7075 was conducted to study the effect of metallurgical melting parameters and compositional variations. 7075 Alloy was melted using a resistance melting furnace and compositional variation in the crucible for varying holding times was evaluated to determine the degree of segregation of key alloying elements. Results have shown some compositional variations.

scholarly journals Influences of Y Additions on the Hot Tearing Susceptibility of Mg-1.5wt.%Zn Alloys

2013 ◽  
Vol 765 ◽  
pp. 306-310 ◽  
Author(s):  
Zhi Wang ◽  
Yuan Ding Huang ◽  
Amirthalingam Srinivasan ◽  
Zheng Liu ◽  
Karl Ulrich Kainer ◽  
...  
Keyword(s):  
Grain Size ◽  
Data Acquisition System ◽  
Hot Tearing ◽  
Mould Temperature ◽  
Crack Volume ◽  
Coarse Microstructure ◽  
Constrained Rod Casting ◽  
Equiaxed Grain ◽  
Zn Alloys ◽  
Hot Tearing Susceptibility

The influences of Y (0.2, 2 and 4 wt.%) additions on the hot tearing behaviour of Mg‑1.5Zn alloys were investigated using a constrained rod casting (CRC) apparatus equipped with a load cell and data acquisition system. The initiation of hot tearing was monitored during CRC experiments. It corresponds to a drop in load on the hot tearing curves. The experimental results indicate that, the hot tearing susceptibility defined by the total crack volume, which was measured by the wax penetration method, decreases with increasing the content of Y at a mould temperature of 250 °C. The reduced susceptibility is attributed to the effect of Y on the solidification behaviour: it shortens the freezing range and reduces the grain size. The highest susceptibility is observed for Mg-1.5Zn-0.2Y alloy. It is caused by its coarse microstructure and relatively larger solidification range. In contrast, the lowest susceptibility is observed for Mg-1.5Zn-4Y alloy with a small equiaxed grain microstructure. In addition, the healing of hot cracks by the subsequent refilling of the remained liquid at the later stage of solidification is also beneficial for the alleviation of hot tearing susceptibility in Mg-1.5Zn-4Y alloy.

Hot Tearing Evaluation and Contraction Behaviors of Four AA7xxx Alloys

2015 ◽  
Vol 817 ◽  
pp. 21-26 ◽  
Author(s):  
Qing Ling Bai ◽  
Jun Cheng Liu ◽  
Yue Li ◽  
Hong Xiang Li ◽  
Qiang Du ◽  
...  
Keyword(s):  
Aluminum Alloys ◽  
Hot Tearing ◽  
Thermal Contraction ◽  
Solidification Range ◽  
Complex Interactions ◽  
Zn Content ◽  
Constrained Rod Casting ◽  
Hot Tearing Susceptibility

The hot tearing susceptibilities (HTS) of some AA7×××alloys, AA7050, AA7055, AA7085 and AA7022 were evaluated with constrained rod casting (CRC). Thermal contraction behaviors during solidification were measured as well in a T-shaped setup. The results showed that alloys with HTS from high to low were AA7055, AA7085, AA7050 and AA7022. Zn content in 7××× aluminum alloys seemed to play a major role with respect to the HTS index. Remarkable differences could be seen on thermal contraction behaviors within solidification range for each alloy. The rate and amount of thermal contraction for AA7055 was most prominent, followed by AA7085 and AA7050, while contraction curve of AA7022 was very flat together with least amount of thermal contraction. There was a well consistency between the amount of thermal contraction and HTS. Despite complex interactions of many variables in the formation of hot tear, thermal contraction behaviors within solidification range could give a quick evaluation of hot tearing susceptibility.

Surfaces Modification of Al-Cu Alloys by Plasma-Assisted CVD

2013 ◽  
Vol 199 ◽  
pp. 496-501 ◽  
Author(s):  
Karol Kyzioł ◽  
Łukasz Kaczmarek ◽  
Stanisława Jonas
Keyword(s):  
Wear Resistance ◽  
Copper Alloys ◽  
Chemical Vapour ◽  
Argon Plasma ◽  
High Strength ◽  
Aviation Industry ◽  
Cu Alloy ◽  
Cu Alloys ◽  
Aluminum Copper Alloys ◽  
Pre Treatment

Aluminum-copper alloys (Al-Cu) are nowadays widely used in various applications, mainly in automotive and aviation industry, because of their unique properties such as high strength, low density and good corrosion resistance. However, usages of aluminum alloys are partially limited due to their reduced hardness, wear resistance and poor tribological parameters. Desired useful parameters can be improved by application of PA CVD technology. This work presents the results concerning determination and analysis of the structure and the selected properties of the modified surfaces of Al-Cu alloys (2xxx series) that were prepared using plasma assisted MW CVD (Micro-Wave Chemical Vapour Deposition) method. To ensure effectiveness of the substrate modification process, the covered surface was subjected to pre-treatment with argon plasma and/or nitriding process. In conclusion, the research has confirmed that the wear resistance of the Al-Cu alloy can be successfully modified by application of MW CVD technique. The obtained results can serve as a basis in the design of the technology of a-Si:C:N:H layers for diverse applications.

A И-Shaped Curve of Hot Tearing Susceptibility in Magsimal®-59-Based Alloys

2022 ◽  
Vol 327 ◽  
pp. 98-104
Author(s):  
Bo Hu ◽  
De Jiang Li ◽  
Xiao Qin Zeng
Keyword(s):  
Liquid Fraction ◽  
Ternary Eutectic ◽  
Hot Tearing ◽  
Freezing Range ◽  
Eutectic Liquid ◽  
Si Content ◽  
Constrained Rod Casting ◽  
Hot Tearing Susceptibility

The hot tearing susceptibility of Al-6Mg-xSi (x = 0-6.0 wt.%) alloys was studied using constrained rod casting. Addition of Si content resulted in double ternary eutectic reactions and then changed the freezing range and eutectic liquid fraction greatly, which made the hot tearing susceptibility show a И-curve with the increasing of Si content. The И-curve was obviously different from the λ-curve that supported by most researchers.

Tensile Properties and Hot-Tearing Tendencies of 3xxx Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 95-100 ◽  
Author(s):  
Arne Nordmark ◽  
Kjerstin Ellingsen ◽  
Anders U. Johansson ◽  
Mohammed M'Hamdi ◽  
Anne Kvithyld ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Aluminium Alloys ◽  
Solidification Path ◽  
Hot Tearing ◽  
Model Alloy ◽  
Cast House ◽  
Grain Refiner ◽  
Semi Solid ◽  
Set Up ◽  
Hot Tearing Susceptibility

A set-up for tensile testing in the mushy zone allowing for studies of semi-solid mechanical behavior is available at SINTEF. A hot-tearing experimental set-up has recently been developed allowing for investigation of the hot-tearing susceptibility of industrial aluminium alloys and effects of e.g. alloying composition and grain-refiner. Load and temperature are registered during constrained solidification giving information on the mechanical behavior of the alloy during solidification. Two crack-prone alloys in the 3xxx-series (A and B) have been investigated using both techniques and the results analyzed using information about solidification path from a thermo-physical model. Alloy B is found to be mechanically weaker in the interval most susceptible to hot-tearing in agreement with cast-house experience. This study shows that the experimental techniques combined with thermo-physical modeling and characterization allow for a better understanding of the hot-tearing sensitivity of the alloys. 

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