Rheo-Processing of Near-Eutectic ADC12 Alloy

2012 ◽  
Vol 192-193 ◽  
pp. 116-122 ◽  
Author(s):  
Zhao Hua Hu ◽  
Guo Hua Wu ◽  
Peng Zhang ◽  
Wen Jiang Ding
Keyword(s):  
Grain Size ◽  
Solid Fraction ◽  
Casting Machine ◽  
Processing System ◽  
Processing Parameters ◽  
Semisolid Slurry ◽  
Pouring Temperature ◽  
High Solid Fraction ◽  
Average Grain Size ◽  
Pressure Die Casting

It is demonstrated experimentally that by using the mechanical rotational barrel processing system combined with high pressure die casting machine, the near-eutectic ADC12 alloy is possible to be rheo-processed. Microstructural characteristics of the semisolid slurry were investigated in different processing parameters. Microstructural evolution and solidification behavior of the semisolid slurry were discussed. The result shows that, the dendritic primary α-Al was sheared off by the vertical stress supplied by the rotational barrel. With a rotation speed of 30r/min and 40r/min, the semisolid slurry can achieve relatively high solid fraction. When the pouring temperature decreased from 620°C to 580°C, the morphology of the primary α-Al changed from spheroidal to rosette-like. Besides, the average grain size and solid fraction increased with the decreasing of pouring temperature. The solidification of the alloy melt during the rheo-diecasting process is composed of two distinct stages: the primary solidification and the secondary solidification. By using the rheo-diecasting process, the components with fine, spherical and uniformly distributed primary α-Al particles were successfully obtained. As the pouring temperature descended from 605°C to 585°C, the primary α-Al of the rheo-diecasting components had rounder morphology, larger average grain size and higher solid fraction.

Surface Modification and its Influence on the Microstructure and Creep Resistance of Nickel Based Superalloy René 77 / Modyfikacja Powierzchniowa Oraz Jej Wpływ Na Mikrostrukture I Wytrzymałosc Na Pełzanie Odlewów Z Nadstopu Niklu Ren´E 77

2013 ◽  
Vol 58 (1) ◽  
pp. 95-98 ◽  
Author(s):  
M. Zielinska ◽  
J. Sieniawski
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Surface Modification ◽  
Turbine Blades ◽  
Processing Parameters ◽  
Grain Structure ◽  
Creep Tests ◽  
Cobalt Aluminate ◽  
Nickel Based Superalloy ◽  
Average Grain Size

Superalloy René 77 is very wide used for turbine blades, turbine disks of aircraft engines which work up to 1050°C. These elements are generally produced by the investment casting method. Turbine blades produced by conventional precision casting methods have coarse and inhomogeneous grain structure. Such a material often does not fulfil basic requirements, which concern mechanical properties for the stuff used in aeronautical engineering. The incorporation of controlled grain size improved mechanical properties. This control of grain size in the casting operation was accomplished by the control of processing parameters such as casting temperature, mould preheating temperature, and the use of grain nucleates in the face of the mould. For nickel and cobalt based superalloys, it was found that cobalt aluminate (CoAl2O4) has the best nucleating effect. The objective of this work was to determine the influence of the inoculant’s content (cobalt aluminate) in the surface layer of the ceramic mould on the microstructure and mechanical properties at high temperature of nickel based superalloy René 77. For this purpose, the ceramic moulds were made with different concentration of cobalt aluminate in the primary slurry was from 0 to 10% mass. in zirconium flour. Stepped and cylindrical samples were casted for microstructure and mechanical examinations. The average grain size of the matrix ( phase), was determined on the stepped samples. The influence of surface modification on the grain size of up to section thickness was considered. The microstructure investigations with the use of light microscopy and scanning electron microscopy (SEM) enable to examine the influence of the surface modification on the morphology of ’ phase and carbides precipitations. Verification of the influence of CoAl2O4 on the mechanical properties of castings were investigated on the basis of results obtained form creep tests.

Addition of Swarf to Produce a Semi-Solid Slurry during High Pressure Die-Casting of AS9U3 Aluminum Alloy

2019 ◽  
Vol 285 ◽  
pp. 271-276
Author(s):  
Hooman Hadian ◽  
M. Haddad-Sabzevar ◽  
Mohammad Mazinani
Keyword(s):  
High Pressure ◽  
Aluminum Alloy ◽  
Solid Fraction ◽  
Die Casting ◽  
Internal Cooling ◽  
High Solid ◽  
Cooling Agent ◽  
High Solid Fraction ◽  
Semi Solid ◽  
Pressure Die Casting

An internal cooling agent is used in rapid slurry forming (RSF) process to produce a high solid fraction slurry for a short period of time. In the process used in this research, the swarf which is known to be a low enthalpy material was added to the melt as the internal cooling agent. During the process, the swarf started to melt and a semi-solid slurry with a relatively high solid fraction was formed. This slurry was formed by exchanging the enthalpies between the low and high enthalpy materials. A commercial Al-Si-Cu alloy, i.e. AS9U3 Aluminum alloy, was used in this investigation. The microscopic examination showed that the Al-Si eutectic colonies start to melt during the melting process of swarf material resulting in the formation of globular Alpha-Al grains due to the multiplication of secondary dendrites arms. The fracture of dendrites arms and the subsequent spheroidization were suggested to be the origin of non-dendritic globular grains in the final microstructure. The amount of primary globular Alpha-phase was measured by the image analysis software. The results showed that during high pressure die-casting of AS9U3 Aluminum alloy using 4 mm thick samples, around 35 percent solid has been formed at the temperature of 580 oC.

Effects of Processing Conditions on Laser Direct Deposited Alumina Ceramics

2020 ◽  
Author(s):  
John M. Pappas ◽  
Xiangyang Dong
Keyword(s):  
Grain Size ◽  
Processing Parameters ◽  
Thin Wall ◽  
Processing Conditions ◽  
Single Track ◽  
Alumina Ceramics ◽  
Direct Deposition ◽  
Average Grain Size ◽  
Scan Speed ◽  
Laser Direct Deposition

Abstract Additive manufacturing (AM) of high-quality inherently brittle ceramics via laser direct deposition, also known as laser engineered net shaping, is challenging due to high thermal gradients, thermally induced cracks, and porosity, typically accompanied by low powder usage efficiency. It is necessary to have an improved understanding of the effects of processing conditions on the fabricated ceramic parts. In this study, alumina ceramics were fabricated with commercial alumina powders. In particular, this paper studied the effect of laser power and scan speed on single track geometries, thin-wall morphology, grain size, density, and powder efficiency during laser direct deposition of alumina ceramics. A single-track parametric study was first conducted to determine the range of processing parameters that produce quality single-tracks and to aid in matching the z-increment with layer thicknesses. The results showed that increased scan speeds promoted significant grain refinement. Average grain size was reduced by nearly 50% when scan speed was increased from 1000 mm/min to 5000 mm/min. On the other hand, densification reached a maximum of 98% at a scan speed of 1000 mm/min with a slight decrease in density was observed at higher speeds. This indicated a trade-off between porosity and grain size when altering the laser scan speed. Significant advantages of using CO2 lasers for AM of ceramics was also demonstrated with powder usage efficiencies reaching nearly 90% under optimized processing conditions.

Microstructure and Property of Rheo-Diecasting Magnesium-Alloy with Forced Convection Mixing Process

2014 ◽  
Vol 217-218 ◽  
pp. 455-460 ◽  
Author(s):  
Bing Zhou ◽  
Yong Lin Kang ◽  
Ming Fan Qi ◽  
Huan Huan Zhang ◽  
Guo Ming Zhu
Keyword(s):  
Magnesium Alloy ◽  
Tensile Properties ◽  
Forced Convection ◽  
Rotational Speed ◽  
Casting Machine ◽  
Fracture Morphology ◽  
Semisolid Slurry ◽  
Heat Treated ◽  
Mean Size ◽  
Pressure Die Casting

Taking AZ91D magnesium alloy as experimental material, the rheo-diecasting process was implemented by combining the self-developed forced convection rheomoulding device with high pressure die casting machine. Microstructural characteristics of the RDC tensile samples were discussed. Microstructure of semisolid slurry at different rotational speed prepared by FCR device was investigated. Tensile properties and fracture morphology of rheo-diecasting process in different conditions were studied as well. The results indicate that the excellent semisolid microstructure of AZ91D tensile samples can be obtained by forced convection rheo-diecasting process. With the increase of rotational speed, the mean size of the primary particles diminishes and the shape factor increases. The tensile properties of as-cast RDC samples are obviously better than conventional diecasting samples. T6 heat treatment can increase tensile strength and elongation of RDC tensile samples to 286MPa and 6.1%, respectively. The yield strength and elongation of T4 heat treated RDC samples are 100MPa and 12.6%.

An Investigation on the Microstructure and Mechanical Properties of Mg-3Al-1Zn Alloy via Spray Forming

2007 ◽  
Vol 561-565 ◽  
pp. 941-944
Author(s):  
Yong Bing Li ◽  
Hua Cui ◽  
Jin Feng Huang ◽  
Yuan Hua Cai ◽  
Zi Han Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Room Temperature ◽  
Az31 Alloy ◽  
Processing Parameters ◽  
Spray Forming ◽  
Continuous Dynamic Recrystallization ◽  
Extrusion Processing ◽  
Average Grain Size ◽  
Continuous Dynamic

In this study, cylindrical billets of Mg-3Al-1Zn (AZ31) alloy have been synthesized by spray forming technique. The alloy billets were hot-extruded into rods with proper processing parameters. The microstructures and mechanical properties of alloys were investigated. The results indicated that spray formed AZ31 alloys have a homogeneous and equiaxial grains with average grain size of 20μm. The further grain refinement with an average grain size of 5μm was attributed to the continuous dynamic recrystallization during the extrusion processing. The room temperature mechanical properties of the extruded rods are remarkably higher than those of as-cast AZ31 alloy. The average tensile ultimate and yield strength of the alloy are 321MPa and 237MPa, respectively, with an elongation of 15.2%.

One-Step SSM Process by MSC & HPDC for Metallic Components

2008 ◽  
Vol 141-143 ◽  
pp. 103-108
Author(s):  
Hader V. Martínez ◽  
M.F. Valencia ◽  
Alejandro Morales ◽  
Andres F. Duque ◽  
Mauricio Arroyave ◽  
...  
Keyword(s):  
Casting Machine ◽  
Semisolid Slurry ◽  
Semisolid State ◽  
Shaping Process ◽  
Simple Part ◽  
One Step ◽  
Near Net Shape ◽  
Semi Solid ◽  
Solid Alloys ◽  
Pressure Die Casting

The preliminary experimental results on microstructure evolution and simulation of an alternative semisolid route to manufacture near-net shape components are reported. The rheocasting for semi-solid alloys was first performed by conventional mechanical stircasting (MSC), followed by direct shaping of the SSM slurry into a high-pressure die-casting machine (HPDC), thus avoiding the storage and reheated to the semisolid state of the ingots prior the shaping process. To assure high quality for the semisolid slurry, the microstructural evolution was characterized by digital image analyses. The HPDC process of a simple part, simulated using CFD tools (Flow-3D®- Flow Science Inc.) is also reported. By means of such simulation the integrity of shaping components was studied.

scholarly journals Chemometric analysis of alternations in coal ash quality induced by application of different mechano-chemical processing parameters

2017 ◽  
Vol 49 (4) ◽  
pp. 381-397 ◽  
Author(s):  
Anja Terzic ◽  
Lato Pezo ◽  
Ljubisa Andric
Keyword(s):  
Grain Size ◽  
Fly Ash ◽  
Chemical Activation ◽  
Principal Component ◽  
Processing Parameters ◽  
High Energy ◽  
Standard Score ◽  
Sem Images ◽  
Average Grain Size ◽  
The Impact

The coal fly ash mechano-chemical activation conducted via high energy ultra-centrifugal mill was optimized using mathematical and statistical tools. The aim of the investigation was to accent the merits of alternations in ash processing schemes with a referral regarding the enhancement of the ash reactivity that will lead to its higher volume utilization as a cement replacement in concrete design. The impact of the processing parameters sets (number of rotor revolutions, current intensity, activation period, circumferential rotor speed, mill capacity) on the on the product?s quality factors (grain size distribution, average grain size, micronization level, agglomeration tendency, specific surface area) was assessed via Response surface method, Standard score analysis and Principal component analysis in order to obtain the most favorable output. Developed models were able to meticulously predict quality parameters in an extensive range of processing parameters. The calculated r2 values were in the range of 0.846-0.999. The optimal ash sample, that reached the Standard Score as high as 0.93, was produced using a set of processing parameters appropriate to experimental sequence with applied 120 ?m sieve mesh. The microstructural characteristics were assessed using image-processing values and histogram plots of the activated fly ash SEM images.

scholarly journals The Effect of Vacuum Assistance on the Quality of Castings Produced by High Pressure Die Casting Method

2014 ◽  
Vol 14 (2) ◽  
pp. 23-26 ◽  
Author(s):  
M. Łągiewka ◽  
Z. Konopka ◽  
M. Nadolski ◽  
A. Zyska
Keyword(s):  
Surface Roughness ◽  
Die Casting ◽  
Casting Machine ◽  
Vacuum System ◽  
Relative Pressure ◽  
Pouring Temperature ◽  
Second Stage ◽  
Gauge Pressure ◽  
Pressure Die Casting

Abstract The presented work is aimed to deal with the influence of changes in the value of negative (relative) pressure maintained in the die cavity of pressure die casting machine on the surface quality of pressure castings. The examinations were held by means of the modified Vertacast pressure die casting machine equipped with a vacuum system. Castings were produced for the parameters selected on the basis of previous experiments, i.e. for the plunger velocity in the second stage of injection at the level of 4 m/s, the pouring temperature of the alloy equal to 640°C, and the die temperature of 150°C. The examinations were carried on for three selected values of negative gauge pressure: - 0.03, - 0.05, and - 0.07 MPa. The quality of casting was evaluated by comparing the results of the surface roughness measurements performed for randomly selected castings. The surface roughness was measured by means of Hommel Tester T1000. After a series of measurements it was found that the smoothest surface is exhibited by castings produced at negative gauge pressure value of - 0.07 MPa.

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