Application of cyclic upsetting-extrusion to semi-solid processing of AZ91D magnesium alloy

The microstructural evolution of AZ91D magnesium alloy prepared by means of the cyclic upsetting-extrusion and partial remelting was investigated. The effects of remelting temperature and holding time on microstructure of semi-solid AZ91D magnesium alloy were studied. Furthermore, tensile properties of thixoextruded AZ91D magnesium alloy components were determined. The results show that the cyclic upsetting-extrusion followed by partial remelting is effective in producing semi-solid AZ91D magnesium alloy for thixofonning. During the partial remelting, with the increase of remelting temperature and holding time, the solid grain size increases and the degree of spheroidization tends to be improved. The tensile mechanical properties of thixoextruded AZ91D magnesium alloy components produced by cyclic upsetting-extrusion and partial remelting are better than those of the same alloy produced by casting.

Microstructure evolution of processed Mg-Al-Zn alloy by equal channel angular extrusion in semi-solid isothermal treatment

Microstructure evolution of processed Mg-Al-Zn alloy by equal channel angularextrusion(ECAE) in semi-solid isothermal treatment was investigated. The results show that withincreasing semi-solid isothermal treatment temperature, the a phase solid grain size of processedMg-Al-Zn alloy by ECAE increases firstly due to coarsening of a phase solid grains, then decreasesdue to melting of a phase solid grains. With the increase of extrusion passes during ECAE, the aphase solid grain size in the following semi-solid isothermal treatment decreases. The a phase solidgrain size of processed Mg-Al-Zn alloy by ECAE under route B_C is the smallest, while the a phasesolid grain size of processed material by ECAE under route A is the largest. The primary mechanismof spheroid formation depends on the melting of recrystallizing boundaries and diffusion of soluteatoms in the semi-solid state.

Simulation Analysis of Extrusion Process of Equilateral L-shaped Aluminum Profiles Based on Deform-3D

The extrusion deformation process of L-shaped aluminum profiles was numerically simulated using the finite element program Deform-3D.The simulation findings revealed that the deformation of the profiles was mostly caused by unequal material flow velocity,which resulted in the profiles bending.Determine the impact of extrusion parameters on the bending deformation of the profile after studying various parameters that may affect the material flow mode(hole position,extrusion speed).

Effects of Extrusion Processing on Microstructure of 7075Al Alloy in the Semi-solid State

A recrystallization and partial melting(RAP) process was introduced to prepare the semi-solid 7075 aluminum alloy used for thixoforming. In order to obtain an ideal semi-solid microstructure, a series of extrusion experiments were conducted to comparatively investigate the optimum extrusion process parameters. Commercial 7075 Al alloy samples were firstly extruded with varying extrusion ratios below the recrystallization temperature followed by homogenization, then these samples were reheated to the semi-solid state and held in the range of 5 to 50 minutes. The experimental results show that varying process cause the difference in the deformation degree and microstructure for as-extruded samples, resulting in various semi-solid microstructure. It is verified that the formation of equiaxed grains in semi-solid microstructure depends on recrystallization behavior of extruded samples during partial melting. Both relative high extrusion temperature and low extrusion ratio lead to high volume fraction of recrystallized area, thus entirely equiaxed solid grains in semi-solid 7075 Al alloy samples can be obtained finally. In addition, Ostwald ripening was determined as the dominate coarsening mechanism of solid grains in semi-solid state for this 7075 Al alloy during the RAP route. The influence of predeformation on recrystallization behavior of this 7075 Al alloy was discussed in detail.

Development of aluminum rheo-extrusion process using semi-solid slurry at low solid fraction

An aluminum extrusion process is mainly used to fabricate long tubes, beams and rods for various applications. However, this process has a high production cost due to the need for investment of high-pressure machinery. The objective of this work is to develop a new semi-solid extrusion process using semi-solid slurry at low solid fractions. A laboratory extrusion system was used to fabricate aluminum rods with the diameter of 12 ram. The semi-solid metal process used in this study was the gas induced semi-solid （GISS） technique. To study the feasibility of the GISS extrusion process, the effects of extrusion parameters such as plunger speed and solid fi-action on the extrudability, microstructure, and mechanical properties of extruded samples were investigated. The results show that the plunger speed and solid fraction of the semi-solid metal need to be carefully controlled to produce complete extruded parts.

Upper bound analysis of thixotropic extrusion processes of semi-solid magnesium alloys

The methodology was used to conduct the upper bound analysis of thixotropic extrusion process of semi-solid metal. The calculated formulas of deformed power were derived. The relationship among relative stress, frictional factor and die semi-angle were obtained. The relative stress increases with increasing frictional factor, whose value increases with increasing area reduction ratio of a certain die semi-angle. The relative stress firstly decreases and then increases with increasing die semi-angle at a certain area reduction ratio. So, the optimal die semi-angle exists with the corresponding minimum relative stress. The calculated results are in agreement with the experimental ones, which are applied to directing technological practice of axis-symmetry forward extrusion of semi-solid magnesium alloys.

Identification of processing window for extrusion of large thick-walled Inconel 625 alloy pipes using response surface methodology

Identifying suitable processing window is necessary but difficult for achieving favorable microstructure and performance in extrusion of large thick-walled pipe with difficult-to-deform Inconel 625 alloy. In this work, a method was established for identifying the extrusion process window considering temperature control using response surface methodology. Firstly, the response surface models, which correlate temperature rise and peak temperature to key extrusion parameters, have been developed by orthogonal regression based on finite element calculated data. Secondly, the coupled effects of the key extrusion parameters on the temperature rise and peak temperature have been disclosed based on the regression models. Lastly, suitable extrusion processing windows, which are described by contour map of peak temperature in the space of extrusion speed and initial billet temperature, have been established for different extrusion ratios. Using the identified process window, a suitable combination of the key extrusion parameters can be determined conveniently and quickly.

Dynamical Solidification Behaviors and Metal Flow during Continuous Semisolid Extrusion Process of AZ31 Alloy

In this paper, a novel near-net-shape forming process, continuous semisolid extrusion process （CSEP） of AZ31 alloy was proposed, and the dynamical solidification behaviors and metal flow during the process were firstly investigated. During casting AZ31 alloy by this process, non-uniform microstructure distributions and non- equilibrium solidification region near the roll surface were found in the roll-shoe gap. Microstructural evolution from dendrite to rosette and spherical grains was observed during the casting by CSEP. Casting temperature, roll-shoe gap width and cooling ability have great effect on casting process and metal flow, so these factors should be carefully controlled, a proper casting temperature of 710-750℃ is suggested. The white α phases were strongly stretched during the processing, and the remnant liquids are correspondingly distributes along the solid phase boundaries and also show stripped lines.

Hot Extrusion Processing of Al–Li Alloy Profiles and Related Issues:A Review

Al-Li alloy is a new structural material with the advantages of lightweight and high strength.The extrusion profiles of Al-Li alloy are widely used in aerospace and other fields,which can significantly reduce the weight of the aerospace equipment and improve their carrying capacity and service performance.Particular service conditions of structural components in aeronautical and space areas put forward strict requirements on microstructure,mechanical properties,and dimensional precision of Al-Li alloy profiles.Therefore,it places higher requirements on the shape forming and microstructure controlling of the Al-Li alloy profiles.The manufacturing process of the profiles involves billet homogenization,hot extrusion,solution and quenching treatments,artificial aging,and others.The parameters of each process as well as the die structure have important effects on the final performance of the profiles.This article summarizes the main applications and key mechanical properties of Al-Li alloy extrusion profiles.The technologies related to the manufacturing process of the extrusion profiles are summarized and analyzed.The related studies about the evolutions of the microstructure and mechanical properties during homogenization and extrusion processes are reviewed.The developments of the solid solution and quenching treatments as well as the aging strengthening technology for extruded Al-Li alloy profiles are also introduced.The scientific problems and key technologies that need to be solved in the manufacturing of Al-Li alloy extrusion profiles are presented,and the prospect for future development trends in these fields is given.

Unique microstructure and property of a 2024 aluminum alloy subjected to upsetting extrusion multiple processing

The microstructure and hardness of a 2024 aluminum alloy subjected tomulti-pass upsetting extrusion at ambient temperature were studied. Experimental results indicatedthat with the number of upsetting extrusion passes increasing, the grains of the alloy are graduallyrefined and the hardness increases correspondingly. After ten passes of upsetting extrusionprocessing, the grain size decreases to less than 200 nm in diameter and the sample maintains itsoriginal shape, while the hardness is double owing to equal-axial ultrafine grains and workhardening effect caused by large plastic deformation.

Fabrication of fine-grained,high strength and toughness Mg alloy by extrusion−shearing process

A novel extrusion-shearing(ES) composite process was designed to fabricate fine-grained, high strength and tough magnesium alloy. The structural parameters of an ES die were optimized by conducting an orthogonal simulation experiment using finite element software Deform-3D, and Mg-3 Zn-0.6 Ca-0.6 Zr(ZXK310) alloy was processed using the ES die. The results show that the optimized structural parameters of ES die are extrusion angle(α) of 90°, extrusion section height(h) of 15 mm and inner fillet radius(r) of 10 mm. After ES at an extrusion temperature and a die temperature of 350 °C, ZXK310 alloy exhibited good ES forming ability, and obvious dynamic recrystallization occurred in the forming area. The grain size decreased from 1.42 μm of extrusion area to 0.85 μm of the forming area. Owing to the pinning of second phase and formation of ultrafine grains, the tensile strength, yield strength and elongation of alloy reached 362 MPa, 289 MPa and 21.7%, respectively.

Plant-based meat substitutes by high-moisture extrusion:Visualizing the whole process in data systematically from raw material to the products

High-moisture extrusion technology should be considered one of the best choices for producing plant-based meat substitutes with the rich fibrous structure offered by real animal meat products.Unfortunately,the extrusion process has been seen as a“black box”with limited information about what occurs inside,causing serious obstacles in developing meat substitutes.This study designed a high-moisture extrusion process and developed 10 new plant-based meat substitutes comparable to the fibrous structure of real animal meat.The study used the Feature-Augmented Principal Component Analysis(FA-PCA)method to visualize and understand the whole extrusion process in three ways systematically and accurately.It established six sets of mathematical models of the high-moisture extrusion process based on 8000 pieces of data,including five types of parameters.The FA-PCA method improved the R^(2) values significantly compared with the PCA method.The Way 3 was the best to predict product quality(Z),demonstrating that the gradually molecular conformational changes(Y^(n'))were critical in controlling the final quality of the plant-based meat substitutes.Moreover,the first visualization platform software for the high-moisture extrusion process has been established to clearly show the“black box”by combining the virtual simulation technology.Through the software,some practice work such as equipment installation,parameter adjustment,equipment disassembly,and data prediction can be easily achieved.

Effect of hot extrusion process on microstructure and mechanical properties of hypereutectic Al-Si alloys

The hypereutectic Al-Si alloy was fabricated by hot extrusion process after solidified under electromagnetic stirring,and the microstructure and mechanical properties of the alloy were studied.The results show that the ultimate tensile strength and elongation of the alloy reached 229.5 MPa and 4.6%,respectively with the extrusion ratio of 10,and 263.2 MPa and 5.4%,respectively with extrusion ratio of 20.This indicates that the mechanical properties of the alloy are obviously improved with the increase of extrusion ratio.After hot extruded,the primary Si,eutectic Si,Mg2Si,AlNi,Al7Cu4Ni and Al-Si-Mn-Fe-Cr-Mo phases are refined to different extent,and the efficiency of refinement is obvious more and more with the increase of extrusion ratio.After T6 heat treatment,the sharp corners of these phases become passivated and roundish,and the mechanical properties are improved.The ultimate tensile strength of the extruded alloy after T6 heat treatment reaches 335.3 MPa with extrusion ratio of 10 and 353.6 MPa with extrusion ratio of 20.

Optimization of extrusion process parameters of Incoloy028 alloy based on hot compression test and simulation

True stress?true strain curves of Incoloy028alloy at high temperature and strain rate were investigated by hot compression test.These curves show that the maximum flow stress decreases with the increase in temperature and the decrease in strain rate.FEM simulation was employed to investigate the influence of temperature,extrusion speed and friction coefficient on the extrusion load,stress,strain and strain rate in the extrusion process.The increase of extrusion temperature results in decrease of load and deformation resistance,but has little influence on strain and strain rate.When extrusion speed changes between200and350mm/s,no obvious change about extrusion load can be found.Sharp peak value up to42500kN emerges in the extrusion load curve and the extrusion process becomes unstable seriously when extrusion speed rises up to400mm/s.Both stress and strain rate increase with the raise of extrusion speed.When friction coefficient is between0.02and0.03,deformation resistance is about160MPa and the strain rate can be limited below70s?1.Successful production of Incoloy028tube verifies the optimized parameters by FEM simulation analysis,and mechanical tests results of the products meet the required properties.

Deformation division of metal flow behavior during extrusion process of 7075 aluminum alloy

To reduce defects caused by non-homogeneous metal flow in conventional extrusion,a die with guiding angle was designed to improve the metal flow behavior. The characteristic quantities such as the second invariant of the deviator stress J2 and Lode's coefficient μ were employed for the division of deformation area. The results show that when the metal is extruded with the guiding angle,no metal flow interface forms at the container's bottom,the dead zone completely disappears,the deformation types of the metal in the plastic deformation area change from three types to one type of tension,and the homogeneity of the deformation as well as metal flow are greatly improved. The non-homogeneous metal flow at the final stage of extrusion is improved,reducing the shrinkage hole at the axis end. The radial stress of the furthest point from the axis is transformed from tensile stress to compressive stress and the axial stress,and decreased from 70.8 to 34.8 MPa. Therefore,the surface cracks caused by additional stress are greatly reduced.

Effects of process parameters and die geometry on longitudinal welds quality in aluminum porthole die extrusion process

By using the rigid-visco-plasticity finite element method, the welding process of aluminum porthole die extrusion to form a tube was simulated based on Deform-3D software. The welding chamber height （H）, back dimension of die leg （D）, process velocity and initial billet temperature were used in FE simulations so as to determine the conditions in which better longitudinal welding quality can be obtained. According to K criterion, the local welding parameters such as welding pressure, effective stress and welding path length on the welding plane are linked to longitudinal welds quality. Simulation turns out that pressure-to-effective stress ratio （ρ/σ） and welding path length （L） are the key factors affecting the welding quality, Higher welding chamber best and sharper die leg give better welding quality. When H=10 mm and D=0.4 mm, the longitudinal welds have the best quality. Higher process velocity decreases welds quality. The proper velocity is 10 mm/s for this simulation. In a certain range, higher temperature is beneficial to the longitudinal welds. It is found that both 450 and 465℃ can satisfy the requirements of the longitudinal welds.

Deformation Processed Cu-15 wt pct Cr Composite Synthesized by Hot Hydrostatic Extrusion of Mechanical Milled Powders

A novel technique was developed for the preparation of Cu-15 wt pct Cr composite with high strength and conductivity. The composite powders with refined microstructure and curly lamellae strengthening phase was first prepared by mechanical milling in favorite milling time and then were hot hydrostatic extruded after pre-densification with sintering or hot pressing. It was shown that the extrusion densified the composite powders well and at the same time the chaos curled strengthening phase was aligned into lines and further deformed as strengthening ribbons. The deformation processed Cu-15 wt pct Cr composite prepared by this technique is of superior conductivity, strength and thermal stability.

Fabrication of AZ31 alloy wire by continuous semisolid extrusion process

A novel technology of continuous semisolid extrusion Process(CSEP) was adopted to produce AZ31 alloy structural materials.Effects of technological conditions on the microstructures of AZ31 alloy during CSEP were studied.During the casting process,the non-uniform distribution of microstructures was found in the roll-shoe gap.Microstructure evolution from dendrite to rosette or spherical grains was observed during the casting process by CSEP.The results show that high casting temperature and large cooling intensity can cause non-equilibrium solidification region near the roll surface,large roll-shoe gap width and high cooling intensity can lead to the formation of discontinuous solidification microstructure and slip plane near the shoe surface,which will finally cause the failure of the casting process.The proper casting temperature range of 730-750 °C,the roll cooling intensity of 0.4 L/s and the roll-shoe gap width of less than 10 mm are suggested.Under the suggested conditions,the product with diameter of 10 mm of AZ31 alloy with smooth surface and homogeneous striped microstructure is obtained.The average strength of the product after heat treatment reaches 270 MPa,and the elongation is 16%.

Prediction of central bursting defects in rod extrusion process with upper bound analysis method

The prediction of central bursting defects in the rod extrusion process through conical dies using the upper bound analysisis investigated. A kinematically admissible velocity field, including the radial and angular velocity components, is proposed. A newcriterion is presented to predict the occurrence of the central bursting defects. Parameter bobt, which represents the risk probability ofcracking, is proposed. It is calculated using the shape of the boundary at the entrance by minimizing the total power dissipationduring the extrusion process. When bobt is equal to or greater than bcr, central bursting occurs. Furthermore, the quantitativerelationships between central bursting defects and process parameters （semi die angle, reduction in area and frictional factor） arestudied. The results show that the central bursting defects are affected primarily by the reduction in area and the friction factor. Thepresented criterion is verified by comparing with the FEM simulation data and the results of the published paper.

Effect of extrusion processing parameters on microstructure and mechanical properties of as-extruded AZ31 sheets

The AZ31 sheets were prepared by extrusion.The effects of the extrusion processing parameters including the temperature extrusion ratio,and structure of the extrusion die on the microstructure and mechanical properties of the as-extruded AZ31 sheets were investigated.The results show that the partial grains grow abnormally.and the mechanical and anisotropic properties of the as-extruded AZ31 sheets have little change at the extrusion temperatures of 380-400℃and the extrusion ratio of 13.3.With the increase of the extrusion ratio,the microstructure of the as-extruded AZ31 sheets by conventional die becomes finer and more uniform,and the elongation rate increases,but the strength decreases and its anisotropy becomes worse.Under the porthole die,finer and more uniform microstructure,higher mechanical properties and better anisotropy can be brought for the as-extruded AZ31 sheets The extruded AZ31 sheets by the porthole die have better anneal process of 300℃and 1 h.