Rheological Behavior of Various Al Alloys during Solidification

Materials Science Forum ◽

10.4028/www.scientific.net/msf.710.35 ◽

2012 ◽

Vol 710 ◽

pp. 35-42

Author(s):

Michel Suéry

Keyword(s):

Ductile Fracture ◽

Cooling Rate ◽

Solid Fraction ◽

Rheological Behavior ◽

Liquid Films ◽

Al Alloys ◽

Tensile Behavior ◽

Controlled Cooling ◽

Sharp Transition ◽

Solid Specimen

This paper is concerned with the tensile behavior of various Al alloys during solidification obtained by using an initially solid specimen heated locally until it becomes fully liquid and then partially solidified at a controlled cooling rate. It is shown that for Al-Cu as well as for Al-Si-Mg alloys, a similar behavior is observed with a sharp transition on the stress-solid fraction curve when the coalescence solid fraction of the dendrites is reached. Below the transition fracture occurs along liquid films for very low stresses whereas beyond this transition, ductile fracture is observed leading to higher stresses.

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The Rheological Behavior of HS6-5-2 Tool Steel for Non-Isothermal Processing

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.192-193.317 ◽

2012 ◽

Vol 192-193 ◽

pp. 317-322

Author(s):

Farzad Hosseini Yekta ◽

S.A. Sadough ◽

Vahid Pouyafar ◽

Amin Jabbari

Keyword(s):

Shear Rate ◽

Cooling Rate ◽

Tool Steel ◽

Solid Fraction ◽

Rheological Behavior ◽

Liquid Fraction ◽

Outer Cylinder ◽

Processing Temperature ◽

Applied Torque ◽

Semi Solid

The rheological behavior of semi-solid tool steel is investigated using a conventional rheometer under cooling rate and shear rate. The processing of steels in semi-solid state is still at development stage due to the high processing temperature involved. The candidate grades of steel for thixoforming are high speed, high carbon, stainless steel and ductile iron. TheHS6-5-2 tool steel has a wide semi-solid range of over 200 C and the required spheroidal microstructure achieved by partial re-melting from as supplied state without any mechanical agitation, indicated the potential of this grade to be investigated in semi-solid processing. For non-isothermal processing an increase of solid fraction related to solidification due to thermal exchanges is observed. In the first series of experiment after melting the feed stock in an alumina cup, the alloy is sheared continuously by a rotating rod with a constant shear rate under three different cooling rates to the 55% corresponding liquid fraction. In the second series of experiment three different shear rates were applied under a constant cooling rate. The apparent viscosity of the slurry as a function of cooling rate and solid fraction is calculated from the applied torque to the outer cylinder. The results show that the slurry viscosity decreases with increasing shear rate and increases with increasing cooling rate and solid fraction. Additionally for a given solid fraction, shear thinning behavior is observed.

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Detection of Quench Induced Precipitation in Al Alloys by Dilatometry

Materials Science Forum ◽

10.4028/www.scientific.net/msf.877.147 ◽

2016 ◽

Vol 877 ◽

pp. 147-152 ◽

Cited By ~ 9

Author(s):

Benjamin Milkereit ◽

Michael Reich ◽

Olaf Kessler

Keyword(s):

Cooling Rate ◽

High Strength ◽

Al Alloys ◽

Age Hardening ◽

Controlled Cooling ◽

Scanning Calorimetry ◽

Cooling Rates ◽

Precipitation Behaviour ◽

In Situ Detection

Quenching is a critical step during the strengthening age hardening of Aluminium alloys. To obtain optimal technological results, parts should be quenched with the upper critical cooling rate. The precipitation behaviour of Al alloys during cooling from solution annealing and thereby the critical cooling rates are typically investigated by in-situ measurements with differential scanning calorimetry (DSC). Conventional DSCs are limited at cooling rates below 10 Ks-1. Unfortunately, medium to high strength Al alloys typically have critical cooling rates between 10 and some 100 Ks-1. Recently it was shown that dilatometry is generally able for in-situ detection of precipitation in Al alloys. Dilatometry allows controlled cooling up to some 100 Ks-1 and therefore covers the cooling rate range relevant. In this work, we aim to show up and discuss possibilities and limitations of dilatometric detection of quench induced precipitates in 2xxx, and 7xxx Al alloys. The basic method will be presented and results will be compared with DSC work.

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Rheological Behavior of Semi-Solid Slurry of A356 Alloy at High Shear and Cooling Rates

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.141-143.409 ◽

2008 ◽

Vol 141-143 ◽

pp. 409-414 ◽

Cited By ~ 6

Author(s):

N. Barman ◽

P. Dutta

Keyword(s):

Shear Rate ◽

Cooling Rate ◽

Solid Fraction ◽

Rheological Behavior ◽

Outer Cylinder ◽

A356 Alloy ◽

High Shear ◽

Concentric Cylinder ◽

Cooling Rates ◽

Series Of Experiments

The rheological behavior of semisolid aluminium alloy (A356) slurry is investigated by using a concentric cylinder viscometer under high cooling rate (30 to 50°C/min) and high shear rate (650 to 1500s-1) conditions. Two different series of experiments are carried out. In all of these experiments, the pellets of A356 alloy are poured into the outer cylinder where they melt completely by resistance heating. When the inner cylinder is placed concentrically, the molten metal resides in the annular space between the cylinders. As the inner cylinder rotates, the alloy is sheared continuously during cooling from a temperature of 630°C, and a slurry forms. In the first series of experiments, for different cooling rates, shearing continues under a constant shear rate until rotation of the inner cylinder stops. During experiments, the temperature of the slurry is measured continuously using a K-type thermocouple, from which the solid fraction is calculated. In the second series of experiments, the molten alloy is cooled and sheared continuously at different shear rates for a given cooling rate. The apparent viscosity of the slurry is calculated by measuring the torque applied to the inner cylinder and its rotational speed. The results show that the slurry viscosity increases with increasing fraction of solid and increasing cooling rate, and it decreases with increasing shear rate. At high values of shear and cooling rates, the viscosity varies gradually up to a solid fraction of about 0.5.

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The relationship between cooling rate, grain size and the mechanical behavior of B2 FeAl alloys

Materials Science and Engineering A ◽

10.1016/0921-5093(93)90623-m ◽

1993 ◽

Vol 165 (1) ◽

pp. 29-34 ◽

Cited By ~ 21

Author(s):

Martin A. Crimp ◽

Krishna M. Vedula

Keyword(s):

Grain Size ◽

Mechanical Behavior ◽

Cooling Rate ◽

Al Alloys ◽

The Relationship

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RESEARCH OF THE INFLUENCE OF SLOW-DOWN COOLING SPEED IN THE INTERVAL OF EUTEKTIC TRANSFORMATION ON THE STRUCTURE AND MECHANICAL PROPERTIES OF CAST IRON CASTINGS

IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY ◽

10.35211/1990-5297-2020-7-242-51-55 ◽

2020 ◽

pp. 51-55

Author(s):

N. I. Gabelchenko ◽

N. A. Kidalov ◽

A. A. Belov ◽

M. D. Bezmogorychnyy ◽

A. I. Gabelchenko

Keyword(s):

Mechanical Properties ◽

Cast Iron ◽

Cooling Rate ◽

Quality Index ◽

Fuel Oil ◽

Controlled Cooling ◽

Slowing Down ◽

Eutectic Transformation ◽

Iron Castings ◽

Cooling Speed

The work is devoted to the study of the effect of slowing down the cooling rate in the interval of eutectic transformation on the structure and mechanical properties of castings from gray doeutectic iron. To slow down the cooling rate in the interval of eutectic transformation, an exothermic carbon-containing additive, fuel oil M-100, was used. It is shown that the use of controlled cooling can significantly increase the quality index of cast iron without introducing additional alloying elements into the composition of cast iron.

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Phase stability and tensile behavior of metastable β Ti-V-Fe and Ti-V-Fe-Al alloys

Materials Characterization ◽

10.1016/j.matchar.2018.06.008 ◽

2018 ◽

Vol 142 ◽

pp. 398-405 ◽

Cited By ~ 13

Author(s):

Weilin Wang ◽

Xianbing Zhang ◽

Jian Sun

Keyword(s):

Phase Stability ◽

Al Alloys ◽

Tensile Behavior

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Effects of Melt Treatment on Dendrite Coherency of A357 Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3886 ◽

2011 ◽

Vol 189-193 ◽

pp. 3886-3890

Author(s):

Zhong Wei Chen ◽

Pei Chen ◽

Li Fan

Keyword(s):

Thermal Analysis ◽

Growth Rate ◽

Cooling Rate ◽

Solid Fraction ◽

Dendrite Growth ◽

A357 Alloy ◽

Dendrite Coherency Point ◽

Melt Treatment ◽

Coherency Point ◽

Dendrite Coherency

The Dendrite Coherency Point (DCP) of A357 alloy was determined after different melt treatments by double thermocouples, and the coherency solid fraction (fscoh) was calculated by thermal analysis. The results of dendrite coherency properties show that fscoh values increase with increased cooling rate for A357 alloy. For A357 alloys, fscoh values increase after grain refined and melt superheat treatment. The coherency point was found to be dependent on not only the morphology of the dendrites but also the dendrite growth rate.

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The effect of the solid fraction on rheological behavior of wrought aluminum alloys in incremental compression experiments with a closed die

Materials Science and Engineering A ◽

10.1016/j.msea.2006.10.019 ◽

2007 ◽

Vol 447 (1-2) ◽

pp. 1-10 ◽

Cited By ~ 86

Author(s):

W.Y. Kim ◽

C.G. Kang ◽

B.M. Kim

Keyword(s):

Aluminum Alloys ◽

Solid Fraction ◽

Rheological Behavior ◽

Wrought Aluminum Alloys ◽

Wrought Aluminum

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The Influence of Cooling Rate on Microstructure, Tensile and Fatigue Behavior of Heat-Treated Al-Si-Cu-Mg Alloys

Materials Science Forum ◽

10.4028/www.scientific.net/msf.884.81 ◽

2017 ◽

Vol 884 ◽

pp. 81-92 ◽

Cited By ~ 3

Author(s):

Lorella Ceschini ◽

Alessandro Morri ◽

Stefania Toschi ◽

Salem Seifeddine ◽

Simone Messieri

Keyword(s):

Cooling Rate ◽

Fatigue Behavior ◽

Fatigue Behaviour ◽

Mechanical Tests ◽

Mg Alloys ◽

Controlled Cooling ◽

Research Activity ◽

Intermetallic Particles ◽

Elongation To Failure ◽

Type Size

Al-Si-Mg alloys are commonly employed for the production of automotive castings. In view of the recent stringent emissions standards and consequent engine downsizing, these components must withstand higher temperatures and stresses than in the past. In this regard, the heat treatable quaternary Al-Si-Cu-Mg alloys gained particular interest in recent years, due to their superior mechanical properties and higher thermal stability. The present research activity was addressed to evaluate the influence of cooling rate on microstructure and consequently on room temperature tensile and fatigue behaviour of the A354 and C355 alloys. Samples for mechanical tests were produced under controlled cooling rates, in order to induce different secondary dendrite arm spacing (SDAS) values, classified as fine (20-25μm) and coarse (50-70μm). The experimental results showed that the cooling rate strongly influences the type, size and morphology of intermetallic particles. The presence of coarse intermetallic phases, mostly Fe-based, observed in coarse SDAS specimens, was reported to strongly affect ultimate tensile strength (UTS), elongation to failure and fatigue strength of both the investigated alloys. A correlation between UTS and fatigue resistance was found, independent of microstructural coarseness.

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