scholarly journals A new methodology for measurement of semi-solid constitutive behavior and its application to examination of as-cast porosity and hot tearing in aluminum alloys

2008 ◽  
Vol 491 (1-2) ◽  
pp. 237-247 ◽  
Author(s):  
A.B. Phillion ◽  
S.L. Cockcroft ◽  
P.D. Lee
Keyword(s):  
Aluminum Alloys ◽  
Hot Tearing ◽  
Constitutive Behavior ◽  
Semi Solid

Reduction of Hot Tearing of Cast Semi-Solid 206 Alloys

2012 ◽  
Vol 192-193 ◽  
pp. 101-106 ◽  
Author(s):  
Alain Lemieux ◽  
Joseph Langlais ◽  
X. Grant Chen
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloys ◽  
Silicon Content ◽  
Hot Tearing ◽  
Silicon Concentration ◽  
Conventional Casting ◽  
Superior Mechanical Properties ◽  
High Silicon ◽  
Semi Solid

The mechanical properties of 206 alloys are among the highest of aluminum alloys. However, these alloys are usually prone to hot tearing. It is known that the addition of silicon can reduce the hot tearing propensity and improve fluidity. However, the commercial 206 alloys used in conventional casting processes limit the silicon concentration ≤0.05 wt% to obtain good mechanical properties. However, the semi-solid forming offers a unique opportunity to increase the silicon content to improve the castability without compromise on mechanical properties. In the present paper, the development of modified 206 alloy compositions to minimize hot tearing during semi-solid forming while maintaining competitive mechanical properties is reported. The effect of high silicon contents with varying copper levels on hot tearing sensitivity is studied. The mechanical properties of a high Si 206 alloy with lowest hot tearing sensitivity are evaluated. It is found that increasing the silicon content in 206 alloys is beneficial to reduce hot tearing. The high Si 206 variants produced by the SEED rheocating process not only reduce significantly the hot tearing sensitivity but also attain superior mechanical properties.

scholarly journals A New Approach to Determine Tensile Stress-Strain Evolution in Semi-Solid State at Near-Solidus Temperature of Aluminum Alloys

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 396
Author(s):  
Jovid Rakhmonov ◽  
Mohamed Qassem ◽  
Daniel Larouche ◽  
Kun Liu ◽  
Mousa Javidani ◽  
...  
Keyword(s):  
Solid State ◽  
Aluminum Alloys ◽  
Accurate Determination ◽  
Solidus Temperature ◽  
Hot Tearing ◽  
Image Correlation ◽  
Correlation Technique ◽  
Stress Strain ◽  
Strain Evolution ◽  
Semi Solid

Accurate determination of the materials’ strength and ductility in the semi-solid state at near-solidus temperatures is essential, but it remains a challenging task. This study aimed to develop a new method to determine the stress-strain evolution in the semi-solid state of aluminum alloys within the Gleeble 3800 unit. Stress evolution was determined by the newly developed “L-gauge” method, which converted the displacement of the “restrained” jaw, measured using an L-gauge, into the force. This method gives the possibility to determine the flow stress more accurately, especially for the very low stress rang (1–10 MPa) in the semi-solid state at near-solidus temperatures. The digital image correlation technique implemented in the Gleeble unit allowed effective measurement of the heterogeneous strain fields evolving within the specimen under tensile loading. Therefore, the stress-strain curves measured in the semi-solid state help to better understand the alloy’s susceptibility to hot tearing. The results of an AA6111 alloy under different liquid fractions (2.8% at 535 °C and 5.8% at 571 °C) were demonstrated. The reliable stress-strain data and heterogenous strain distribution are beneficial to develop the thermomechanical models and hot-tearing criteria.

Impact of Intensification Pressure and Grain Refiner on the Hot Tearing Susceptibility of a Semi-Solid Cast Al-Zn-Mg-Cu Alloy

2019 ◽  
Vol 285 ◽  
pp. 283-289
Author(s):  
Hai Yue Zhao ◽  
Da Quan Li ◽  
Min Luo ◽  
Stephen P. Midson ◽  
Qiang Zhu
Keyword(s):  
Aluminum Alloys ◽  
Grain Refinement ◽  
Hot Tearing ◽  
Commercial Application ◽  
Cast Aluminum ◽  
Grain Refiner ◽  
Cu Alloy ◽  
Intensification Pressure ◽  
Semi Solid ◽  
The Impact

The commercial application of wrought aluminum alloys to semi-solid casting would be extremely beneficial, as wrought alloys often exhibit better strength-ductility combinations than cast aluminum alloys. Semi-solid casting typically reduces the hot tearing tendency, as it requires a globular microstructure and produces grain refinement, but hot tearing often still occurs during the semi-solid die casting of complex-shaped components produced from wrought alloys. This study examined the impact of intensification pressure and grain refinement on the hot tearing tendency of an Al-Zn-Mg-Cu alloy. Semi-solid slurries were produced using the SEED (Swirled Equilibrium Enthalpy Device) process. A specially designed constrained rod mold was used to evaluate hot tearing. Results showed the tendency for hot tearing decreased with increasing of intensification pressure. Grain refinement (with 0.06Ti) was also found to be beneficial to the elimination of hot tearing.

A new investigated method on hot tearing behavior in aluminum alloys

2013 ◽  
Vol 54 (5) ◽  
pp. 377-382 ◽  
Author(s):  
Rongfu Xu ◽  
Hongliang Zheng ◽  
Fengxiang Guo ◽  
Supei Ding ◽  
Xuelei Tian
Keyword(s):  
Aluminum Alloys ◽  
Hot Tearing

scholarly journals Influence of Thermal Aging Parameters on the Characteristics of Aluminum Semi-Solid Alloys

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 746 ◽  
Author(s):  
Khaled Ragab ◽  
Mohamed Bouazara ◽  
Xiao Chen
Keyword(s):  
Electron Microscopy ◽  
Aluminum Alloys ◽  
Thermal Aging ◽  
Aging Treatment ◽  
Load Variations ◽  
Transmission Electron ◽  
Semisolid Alloys ◽  
Automotive Parts ◽  
Semi Solid ◽  
Solid Alloys

The current study aimed at analyzing the response of semisolid A357 aluminum alloys to unconventional thermal treatment cycles of T4/T6/T7 conditions. The mechanical, electrical, and microstructural characterizations of such semisolid alloys were investigated. The microstructure evolutions of Fe-intermetallic phases and strengthening precipitates were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The mechanical failure of such semi solid A357 aluminum alloys, used for suspension automotive parts, is mostly related to cracking issues which start from the surface due to hardness problems and propagate due to severe load variations. For these reasons, the multiple thermal aging cycles, in this study, are applied to enhance the mechanical properties and to have compromised values compared to those obtained by standard thermal treatments. The results obtained in this work indicate that the heat treatment of this alloy can be optimized. The results showed that the optimum characteristics of A357 semisolid alloys were obtained by applying thermal under-aging cycle, interrupted thermal aging cycles and a T7/T6 two steps aging treatment condition. The electrical conductivity and electron microscopy were applied in this study to analyze the characteristics of hardening phases formed due to different aging cycles applied to the alloys investigated.

Continuous Casting of Magnesium Billets for Semi-Solid Processing

2005 ◽  
Vol 475-479 ◽  
pp. 517-520
Author(s):  
Hwa Chul Jung ◽  
Kwang Seon Shin
Keyword(s):  
Aluminum Alloys ◽  
Continuous Casting ◽  
Magnesium Alloys ◽  
Casting Process ◽  
Az91 Alloy ◽  
Attractive Alternative ◽  
Limited Information ◽  
Continuous Casting Process ◽  
Dendritic Microstructure ◽  
Semi Solid

Semi-solid processing is recognized as an attractive alternative method for the near net-shape production of engineering components. Although there has been a significant progress in semi-solid processing of aluminum alloys, very limited information is available on semi-solid processing of magnesium alloys, except for the thixomolding process. Continuous casting process has been utilized to produce the billets with the desirable cross-section at a reduced production cost for many metals, such as steel, copper and aluminum alloys. It has also been commercially utilized to produce the aluminum billets with non-dendritic microstructure for subsequent thixocasting process. However, continuous casting of magnesium billets for semi-solid processing has not yet been commercialized due to the difficulties involved in casting of magnesium alloys. In the present study, a continuous casting process has been developed for the production of the cylindrical billets of magnesium alloys for the subsequent thixocasting process. In order to obtain the desired non-dendritic microstructure with an excellent degree of homogeneity both in microstructure and composition, an electromagnetic stirring system has been utilized. A continuous casting process has been proven to be an efficient way to produce the high quality billets of magnesium alloys for semi-solid processing. A prototype air conditioner cover was produced using the continuously cast billets of AZ91 alloy.

Semi-Solid Processing of Aluminum Alloys

2016 ◽  
Author(s):  
Shahrooz Nafisi ◽  
Reza Ghomashchi
Keyword(s):  
Aluminum Alloys ◽  
Semi Solid
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