Chongqing, China
Chongqing, China

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Xu S.-Y.,Chongqing University | Xu S.-Y.,Chongqing Sinost Company Ltd | Long S.-Y.,Chongqing University | Liao H.-M.,Chongqing University | Cao F.-H.,Chongqing University
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2010

Tensile experiments were carried out for as-extruded AZ31 magnesium alloy under different strain-rates on a static tensile testing machine and tensile impact testing apparatus. Fracture morphology was analyzed by SEM. The results show that yield strength and ultimate tensile strength of the alloy increases with the increase of strain rate, and the failure strain decreases with increasing strain rate, however, no significant effect of strain rate on Young's modulus E is observed. The Johnson-Cook model is employed in characterizing the effect of strain rate on mechanical behavior of the alloy and the calculated result is accordant well with the experimental results. SEM fractographic analysis indicates that a mixed mode of predominant quasi-cleavage fracture with local cleavage fracture presents for both static and impact loading.

Zha J.,Chongqing University | Zha J.,Chongqing SinoST Company Ltd | Xu S.,Chongqing University | Xu S.,Chongqing SinoST Company Ltd | And 3 more authors.
Advanced Materials Research | Year: 2011

in the present paper, the current state of magnesium scrap recycling via melt refinement was reviewed and the difficulties confronted in the developing fluxless techniques were highlighted. Then, the working principle of a fluxless technique newly developed in China was briefly introduced followed by chemical and light microscopy investigation of the processing quality of the recycled ingots in comparison with the commercial ingot produced with predominant flux processing to have a first insight into the difference of the two refining techniques. The results indicate that a stable, continuous and cost effective melt refinement can be achieved with the commercial Mg scraps in-house fluxless recycling system. © (2011) Trans Tech Publications.

Long S.,Chongqing University | Long S.,Chongqing SinoST Company Ltd | Zha J.,Chongqing University | Zha J.,Chongqing SinoST Company Ltd | And 4 more authors.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2011

Vacuumming of die cavity is an effective way of producing quality castings free of defects associated with cavity gases.After an evaluation of the vacuuming behaviors of the vacuuming die casting technologies currently used in industry, it was pointed out that the dissatisfaction of current technologies steams from the commonly low vacuuming rate needed to effectively stop the melt flow from pennetrating into vacuuming system.In accordence with the vacuuming knetics of a die cavity, it is highlighted that an effective vacuuming relies on the kinetic response rate of the vacuuming system and the vacuum degree achieved before high speed die-filling in condition that the vacuuming channel could be effectively closed up.Enlarging the diameter and reducing the length of the vacuuming channel are the key criteria to a successful exhausting channel design.The application of a new type vacuuming system meeting the mentioned criteria was shown.

Gan X.,Chongqing University | Long S.,Chongqing University | Long S.,Chongqing SinoST Company Ltd | Liu W.,Chongqing University | Pu Y.,Chongqing University
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2011

Density of the die castings was improved as a result of effectively reducing gas hole in the castings through vacuum die casting. It was a key point for rapid exhaust in cavity in vacuum die casting, which directly affected the quality of die castings. Through analyzing flow process of gas in vacuum exhausting pipe , main factors influencing vacuum rate in cavity were investigated, and optimized processing parameters were presented to rapidly realize high vacuum rate in cavity. The results show that it is beneficial for rapid realization of high vacuum rate in cavity by setting exhausting pipe with large section and short distance and high exhausting speed as well as small cavity volume.

Zhang X.,Chongqing University | You G.,Chongqing University | You G.,National Engineering Research Center for Magnesium Alloys | Zha J.,Chongqing University | And 3 more authors.
Xiyou Jinshu Cailiao Yu Gongcheng/Rare Metal Materials and Engineering | Year: 2011

HFC125 gas is an effective ignition-proof protection to high temperature magnesium alloy melt. The surface films from the reaction between HFC125/N 2 gas mixture and Mg alloy melt was studied under the weak or strong air convection condition. The results show that under the condition of weak air convection, almost no oxygen ion exists in the obtained surface film, while under the condition of strong air convection, the surface film contains a small amount of oxygen ion. The protection effect does not change obviously for the both working conditions. © 2011, Northwest Institute for Nonferrous Metal Research. Published by Elsevier BV. All rights reserved.

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