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Bi S.,Dalian Jiaotong University | Yun X.-B.,Dalian Jiaotong University | Pei J.-Y.,Dalian Jiaotong University | Yan Z.-Y.,Dalian Konform Technical Co. | Zhang X.,Dalian Konform Technical Co.
Suxing Gongcheng Xuebao/Journal of Plasticity Engineering | Year: 2016

Effects of wheel angular velocity on forming, microstructure and mechanical properties of Al-Sr alloy during continuous extrusion were investigated by using finite element (FE) simulation and experiments. The temperature distributions of the die and the temperature, velocity and effective strain distributions of the billet at different extrusion wheel angular velocities were numerically analyzed and the microstructure and mechanical properties of actual continuous extrusion products at different extrusion wheel angular velocities were analyzed by using metallographic observation and tensile test. The results show that the temperature of the billet begins to increase after the billet enters into the cavity during the process. The highest temperature and velocity occur at the die exit and the maximum effective strain occurs at the rectangular bending area. When the wheel angular velocity increases from 4r·min-1 to 7r·min-1, the highest temperature of the billet in the cavity and the die exit increases from 460℃ to 514℃ and from 490℃ to 527℃, respectively; the size of Al4Sr phase reduces and the morphology of Al4Sr phase in the products changes from blocky shape to particulate shape; the tensile strength rises from 98.7MPa to 106.9MPa and the elongation changes slightly, maintaining at about 11%. © 2016, Editorial Board of Journal of Plasticity Engineering. All right reserved.


BI S.,Dalian Jiaotong University | YUN X.-B.,Dalian Jiaotong University | PEI J.-Y.,Dalian Jiaotong University | ZHAO Y.,Dalian Jiaotong University | And 2 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2017

The microstructure evolution of Al–Sr master alloy during continuous extrusion was investigated using X-ray diffractometer, scanning electron microscope and transmission electron microscope. Results indicate that the continuous extrusion process could change the Al4Sr particles of the alloy significantly in size and morphology. The as-cast needle-like Al4Sr particles are broken into small blocks in upsetting zone and crushed heavily in adhesion zone. Plenty of dislocations get tangled up in right-angle bending zone. Al4Sr particles grow in the extending zone. Finally, Al4Sr particles in products are approximately 28 μm in length. Al2Sr particles precipitate during the process. Compared with products by horizontal extrusion, Al4Sr particles by continuous extrusion are finer and distribute more evenly. © 2017 The Nonferrous Metals Society of China


Zhao Y.,Dalian Jiaotong University | Song B.,Dalian Jiaotong University | Song B.,Dalian Konform Technical Ltd Company | Yan Z.,Dalian Konform Technical Ltd Company | And 2 more authors.
Journal of Materials Processing Technology | Year: 2016

Based on the continuous extrusion machine LLJ350, experiment and Deform numerical simulation were conducted to analyze the metal flow and welding process during the continuous extrusion of AA6063 aluminium alloy with double billets. The microstructure and mechanical properties of extrusion welds were investigated through optical microscopy, scanning electron microscopy, and tensile tests. The results reveal that the oxides on the billet surface participate in the metal flow and affect the microstructure and mechanical properties of the extrusion welds. The extrusion weld exhibits bud morphological characteristics on the cross-section of the extrudate, and the welding quality of the bottom portion is superior to that of the upper portion. The welding lines are mixed with fine grains of several micrometers, and the surrounding area contains grains with a size of several hundred micrometers. When the specimens fracture at the weld, the macrofracture forms with a striped surface; by contrast, the microfracture displays a streaky structure, which includes striped protrusions and small dimples of several micron diameters. And it is also found that the extrusion welds slightly affect tensile strength, but markedly influence extrudate elongation. © 2016 Published by Elsevier B.V.


Jiang C.,Dalian Jiaotong University | Zhao Y.,Dalian Jiaotong University | Song B.-Y.,Dalian Jiaotong University | Song B.-Y.,Dalian Konform Technical Company LTD | And 4 more authors.
Suxing Gongcheng Xuebao/Journal of Plasticity Engineering | Year: 2014

The continuous extrusion of aluminum tube with double billets is a kind of high efficient aluminum tube manufacturing technology. In order to guarantee the uniformity of metal flow, the continuous extrusion of aluminum tube with double billets needs the confluent die. The confluent die structure is one of the important factors that affect metal forming. According to the characteristics of continuous extrusion forming, based on the HyperXtrude software, the finite element model of the continuous extrusion of aluminum tube with double billet was established. Through numerical simulation of steady continuous extrusion of aluminum tube, the comparative analysis of the metal flow with different confluent die structure schemes was conducted. The experiments for 6063 aluminum alloy tubes were conducted on LLJ350 continuous extrusion machine, and the microstructure and mechanical properties were observed. The results show that outlet diameter of the confluence area in continuous extrusion of aluminum tube with double billets has important influence on the uniformity of the metal flow. When the outlet diameter less than three the periphery diameter of the port hole, the metal flow velocity becomes more consistent, the wall thickness beomes more uniform, and the plasticity has been improved significantly. While, the outlet diameter change has little effect on grain size and tensile strength.


Zhao Y.,Dalian Jiaotong University | Song B.-Y.,Dalian Jiaotong University | Song B.-Y.,Dalian Konform Technical Ltd Company | Yun X.-B.,Dalian Jiaotong University | And 5 more authors.
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2012

The effect of flow passage length in the die cavity and extrusion wheel velocity on the shape of aluminum sheath during the continuous extrusion sheathing process was analyzed by using finite element methods based on software DEFORM 3D and experimentally validated. The results show that by increasing the flow passage length, the velocity of metal at the cross-section of sheath tends toward uniformity, the values of the bending angles of sheath gradually approach the ideal value of zero and the cross-section exhibits a better shape. The extrusion wheel velocity has negligible effects on the bending shape and cross-section of the sheath product when a long flow passage is used. © 2012 The Nonferrous Metals Society of China.


Zhao Y.,Dalian Jiaotong University | Song B.,Dalian Jiaotong University | Song B.,Dalian Konform Technical Ltd Company | Pei J.,Dalian Jiaotong University | And 5 more authors.
Journal of Materials Processing Technology | Year: 2013

Experiments and numerical simulations were conducted to analyze the continuous extrusion of AA6063 aluminum alloy under extrusion wheel angular velocities of 0.52, 0.78, 1.04 and 1.3 rad/s. Simulation results indicate that variations in extrusion wheel velocity directly affect material deformation and significantly influence the maximum extrusion temperature. This work also reveals that deformation and temperature have opposing effects on the microstructure of the resulting product. A greater wheel velocity causes a higher strain rate and extrusion temperature. Increasing the wheel velocity, at an initially low speed, causes a large increase in strain rate. This results in a decrease in grain size. In contrast, at high wheel velocities, further increases to wheel velocity have much less effect on the strain rate, leading to an increase in grain size as the increased extrusion temperature dominates the mechanics of grain growth. Tensile test results demonstrate that the tensile strength of the resulting aluminum extrusions mainly depends on the exit temperature, which is decided by the deformation speed. Tensile strength and hardness slightly increase with increased deformation speed. Extremely high extrusion temperature results in brittle failure and low mechanical properties of the resulting product when the extrusion speed reaches 1.3 rad/s. This paper suggests that an optimum extrusion wheel velocity, which will generate products with good mechanical properties, exists. © 2013 Elsevier B.V. All rights reserved.


Zhao Y.,Dalian Jiaotong University | Song B.-Y.,Dalian Jiaotong University | Li B.,Dalian Jiaotong University | Yan Z.-Y.,Dalian Konform Technical Ltd Company | Zhang X.,Dalian Konform Technical Ltd Company
Suxing Gongcheng Xuebao/Journal of Plasticity Engineering | Year: 2015

Continuous extrusion with double feedstock is a high efficient forming process for manufacturing aluminum products with high width-to-thickness ratio. Based on the numerical simulations, the contrastive analysis of the AA6063 continuous extrusion expansion forming with single feedstock and double feedstock is carried. Compared with the extrusion with single feedstock, in the continuous extrusion with double feedstock, the metal flow is optimized, the distribution of extrusion temperature, velocity and effective strains are more uniform, and the extrusion wheel torque and the abutment force are lower. So as for the expansion forming, the continuous extrusion with double feedstock has more advantages than the extrusion with single feedstock. The extrusion weld seam in expansion forming presents petal shape, and the grain size of weld seam is greater than the matrix. The mechanical properties testing results show that the extrusion weld has an effect on the mechanical properties of the products. When the tensile force direction is perpendicular to the extrusion weld, the performance of the weld has the biggest effect on the product. ©, 2015, Beijing Res. Inst. of Mechanical and Elec. Technology. All right reserved.

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