Suzhou Research Institute for Nonferrous Metals

Suzhou, China

Suzhou Research Institute for Nonferrous Metals

Suzhou, China
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Nie F.,Dalian University of Technology | Dong H.,Dalian University of Technology | Li P.,Dalian University of Technology | Zhao Z.,Suzhou Research Institute for Nonferrous Metals | And 2 more authors.
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2016

Lap joining between wrought 6061-T6 and cast A356-T6 aluminum alloys plates by direct current pulse MIG welding is investigated. The mechanical property, microstructure and composition of the joints are analyzed. The tensile results indicate that the maximum tensile strength of the joints is 95 MPa with the welding speed of 10 mm/s and joint design with A356-T6 aluminum alloy as upper plate. The samples during tensile test fail mainly in weld through mixed fracture mode. The analysis on the microstructure and composition of the joints shows that the segregation of Fe and Mg occurs in the partially melted zone on A356 aluminum alloy side, resulting in formation of flake-like Al-Fe-Si phases and Al-Fe-Mg-Si particles, and these Fe-rich phases can weaken the joints. Grain boundary liquation occurs in the partially melted zone on 6061 aluminum alloy side, which is composed of Al-Mg-Si-Cu phases and solute-depleted α-Al zone, and a little Fe segregated near this structure. The weakest position locates at the root of the lap joint, where the tensile samples crack and finally fracture through the weld. © 2016 Journal of Mechanical Engineering.


Hiromi N.,China Institute of Technology | Hiromi N.,Suzhou Research Institute for Nonferrous Metals | Wu Y.,China Institute of Technology
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2016

Recent progress in eutectic silicon modification of Al-Si alloys was summarized, and application status of the main modifier and key factors affecting modification treatment were reviewed, focusing on influences of modifiers on the porosity in castings and the interaction between modifiers and grain refiners. Recently, the research on the widest used Na and Sr series modifiers is concentrated on the mechanism and solutions on porosity increase in castings caused by modification. The cooling rates and alloying elements are two important factors affecting the modification. The method to improving the modification level of eutectic silicon in multi-element Al-Si alloys at a lower cooling rate is still an important research direction. The nature of mutual poisoning effect between Sr and α-Al grain refiners is the reaction between Sr and refinement particles resulting in efficient content reduction of both modifier and grain refiner. By rational control of content of modifier and grain refiner in the melt and the addition technique, the well-modified eutectic silicon and fine α-Al grains can be achieved. In addition, development of novel Al-(Si)-Sr-(Ti)-B master alloy is also an efficient way to avoiding mutual poisoning. © 2016, Journal Office of Special Casting and Nonferrous Alloys. All right reserved.


Li Z.,Shanghai JiaoTong University | Li Z.,Suzhou Research Institute for Nonferrous Metals | Luo A.A.,Ohio State University | Wang Q.,General Motors | And 2 more authors.
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2016

This paper investigates the fatigue properties and deformation behavior of a newly developed Mg-2.96Nd-0.21Zn-0.39Zr magnesium alloy wheel in both as-cast and T6 conditions. Compared with the as-cast alloy, the T6-treated alloy shows a significant increase in fatigue strength and cyclic stress amplitude. This is believed to be attributed to the change of defect type from porosity to oxides and the increased matrix strength in the T6 (peak-aged) condition. For the as-cast alloy wheel, fatigue failure mainly originated from the cast defects including porosity, oxide film, and inclusion at or near the sample surface. In the T6-treated alloy, however, oxides and inclusions or slip bands initiate the fatigue cracks. Solution treatment appears to reduce or eliminate the shrinkage porosity because of grain growth and dissolution of as-cast eutectic phases in the grain boundaries. The cyclic stress amplitude of the as-cast alloy increases with increasing the number of cycles, while the T6-treated alloy shows cyclic softening after the stress reaches a maximum value. The Coffin–Manson law and Basquin equation can be used to evaluate the life of low cycle fatigue. The developed long crack model and multi-scale fatigue (MSF) models can be used to predict high-cycle fatigue life of the Mg-2.96Nd-0.21Zn-0.39Zr alloys with or without casting defects. © 2016 The Minerals, Metals & Materials Society and ASM International


Ji Y.,Suzhou Research Institute for Nonferrous Metals | Zhong H.,Suzhou Research Institute for Nonferrous Metals | Zhong H.,Monash University | Hu P.,Suzhou Research Institute for Nonferrous Metals | Guo F.,Suzhou Research Institute for Nonferrous Metals
Materials and Design | Year: 2011

Thermodynamic calculation was employed to predict the influence of Si content on the ageing behavior of Al-Mg-Si-Cu alloys. In addition, experiments were carried out to verify the predictions. The results show that thermodynamic calculation can predict the effect of Si content on the ageing behavior of the studied alloys. This study further proposes that the hardness level of alloys during ageing is directly related to the Si content in the as-quenched supersaturated solution, while the precipitation strengthening effect is directly related to the Mg2Si level of the alloys. © 2011 Elsevier Ltd.


Zhao P.-Z.,Suzhou Research Institute for Nonferrous Metals | Zhao P.-Z.,Beijing Institute of Technology | Liu J.,Suzhou Research Institute for Nonferrous Metals | Chi Z.-D.,Beijing Institute of Technology
Transactions of Nonferrous Metals Society of China (English Edition) | Year: 2014

The correlation between Si content (0.1%-0.5%, mass fraction) and pulse laser welding performance of Al-Mn-Mg aluminum alloy sheets was studied. The sheets were fabricated in the laboratory, with gauge of 0.45 mm, H16 temper by pulse laser welding. It was found that no cracking existed in the welding pool as Si content was below 0.34%. However, when the Si content increased to 0.47%, cracking formed in the welding pool. Microstructure observations indicated that residual eutectic phases distributed at the grain boundaries were discontinuous and appeared to be small particles in lower Si content alloys; the residual eutectic phases distributed at the grain boundaries were partially continuous and appeared to be films in higher Si content alloys. These phenomena could explain why Si content adversely affected the laser welding performance. © 2014 The Nonferrous Metals Society of China.


Kou L.-Y.,Hunan University | Jin N.-P.,Hunan University | Zhang H.,Hunan University | Han Y.,Suzhou Research Institute for Nonferrous Metals | And 2 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2010

The flow stress behavior of 7150 aluminum alloy during hot compression deformation was studied by thermal simulation test at the deformation temperature of 300-450 °C and the strain rate of 0.01-10 s-1 on the Gleeble-1500 thermal-mechanical simulator. The results show that the flow stress increases with increasing strain and tends to be constant after a peak value. The peak stress increases with increasing strain rate, and decreases with increasing deformation temperature, which can be represented by a Zener-Hollomon parameter in the hyperbolic sine equation with the hot deformation activation energy of 226.6988 kJ/mol. With increasing temperature and decreasing strain rate, the elongated grains in the deformed samples are coarsened and the size of subgrain increases; the number of fine grain in grain boundary also increases, indicating that the main softening mechanism of the alloy during hot compression deformation transforms from dynamic recovery to dynamic recrystallization.


Feng D.,Jiangsu University of Science and Technology | Zhang X.,Central South University | Liu S.,Central South University | Han N.,Suzhou Research Institute for Nonferrous Metals
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2016

The effects of grain size inhomogeneity in large size ingots on hot deformation behaviors of a new high strength Al-7.68Zn-2.12Mg-1.98Cu-0.12Zr alloy were investigated using Gleeble-3500 test machine at 300~450℃ with strain rates from 0.1 to 10 s-1. SEM observation shows that the grain size in surface layer of the ingot is finer than that in central layer. During hot deformation, the flow stress of the sample with fine grain (surface layer) is lower than that of the sample with coarse grain (central layer) under high temperature and low strain rate conditions. The hot deformation activation energies (Q) of 140 and 125.4 kJ/mol are obtained for fine grain microstructure and coarse grain microstructure, respectively. The flow stresses were predicted by a two-stage type constitutive model based on the dislocation density theory, and the dynamic recrystallization softening equations were established for the microstructures of fine grain and coarse grain. Electron Back-Scattered Diffraction (EBSD) observations reveal that the alloy exhibits dynamic recovery at temperatures ranging from 300 to 400℃ and dynamic recrystallization (DRX) at 450℃ with low strain rate (0.1 s-1). The DRX grains nucleate at the original grain boundaries. As a result, the DRX fracture is higher in finer grain (surface layer) microstructure due to the higher grain boundary density. © 2016, Science Press. All right reserved.


Zhang H.T.,Northeastern University China | Cui J.Z.,Northeastern University China | Nagaumi H.,Suzhou Research Institute for Nonferrous Metals
Advanced Materials Research | Year: 2014

In this paper, Low frequency electromagnetic field and air knife are applied simultaneously to produce large-size AA 7055 aluminum alloy ingots during DC casting. Moreover, the effects of low frequency electromagnetic field and air knife on macro-physical fields during DC casting as well as microstructure and crack in the ingots are studied and analyzed by the numerical and experimental methods. Comparison of the calculated results indicates that applying electromagnetic field can modify the flow direction and increase the velocity of melt flow and homogenize the distribution of temperature in the sump, and applying air knife can homogenize the distribution of temperature and decrease the stress and strain in the solidified ingots. Further, the microstructure of the billet is refined remarkably and the crack is eliminated by applying electromagnetic field and air knife during DC casting because of modification of the macrophysical fields. © (2014) Trans Tech Publications, Switzerland.


Xu Y.,Suzhou Research Institute for Nonferrous Metals | Wang J.C.,Suzhou Research Institute for Nonferrous Metals | Guo S.J.,Suzhou Research Institute for Nonferrous Metals | Li X.T.,Suzhou Research Institute for Nonferrous Metals | Xue G.X.,Suzhou Research Institute for Nonferrous Metals
Journal of Materials Processing Technology | Year: 2011

A comprehensive mathematical model, based on the commercial package FLUENT, was developed to describe heat transfer, fluid flow and solidification during the steady-state of direct-chill (DC) casting 7050 aluminum alloy ingots. In order to verify the mathematic model and boundary conditions applied in the simulation, the temperature fields of 180 mm × 360 mm 7050 ingots were calculated and compared to the experimental results during conventional casting and water-restricted panel applied casting. There was a perfect agreement between them. Based on the mathematic model and the boundary conditions which were verified, the temperature fields of ingot with different water-restricted panel position were investigated. The cooling rate of the ingot was decreased because the water-restricted panel removes the coolant from the ingot surface. The higher the panel position, the slower the cooling rate. The hot-tearing susceptibility of ingot during casting could be suppressed as the slow cooling rate of ingot profits the stress relieving. In addition, the sump depth is sensitive to the panel position, the higher the panel, the deeper the sump. The sump depth increases remarkably when the panel is applied above the sump bottom during conventional casting, while increases slightly when the panel is applied below it. © 2010 Elsevier B.V. All rights reserved.


Han Y.,Suzhou Research Institute for Nonferrous Metals | Ma K.,Suzhou Research Institute for Nonferrous Metals | Li L.,Suzhou Research Institute for Nonferrous Metals | Chen W.,Suzhou Research Institute for Nonferrous Metals | Nagaumi H.,Suzhou Research Institute for Nonferrous Metals
Materials and Design | Year: 2012

The microstructure and mechanical properties of Al-Mg-Si-Cu alloy with high manganese content were studied in the present work to develop a new alloy. The microstructure features were quantificationally determined by a combination of scanning electron microscope and high resolution transmission electron microscopy. The dominant strengthening precipitates comprising the needle-shaped pre-β'(or β') and lath-shaped Q' phases were identified in the T6 temper. With the increase of magnesium content, S phase was promoted to precipitate to give an enhancement in strength. The yield strength of the examined alloys with high manganese content was found to be about 52-65% higher than that of commercial 6061 alloy. It was considered that, in addition to the strengthening precipitates, Mn dispersoids generating the dispersion hardening effect and the homogeneous deformation contributed a lot to the favorable mechanical properties. © 2012.

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