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Zhu Q.,South China University of Technology | Zhang X.,South China University of Technology | Chen W.,South China University of Technology | Wang G.,Guangdong Huajin Advanced Alloys Industrial Company Ltd | Chen J.,Guangdong Huajin Advanced Alloys Industrial Company Ltd
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2013

Zinc alloy worm gears were produced by squeeze casting. The process and defects such as stratification, bubble, crack, were introduced. The origination of these defects was described, and the coun-termeasures were presented. Meanwhile, the feasibility was verified by the practical production.


Zhu Q.-L.,South China University of Technology | Zhang X.-M.,South China University of Technology | Wang G.-L.,Guangdong Hua Jin Advanced Alloys Industrial Company Ltd | Chen J.-J.,Guangdong Hua Jin Advanced Alloys Industrial Company Ltd
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2013

The zinc alloy worm gear was produced by squeezing casting. The microstructure and mechanical properties of the zinc alloy worm gear were investigated by metallurgical microscope and electron universal test machine. The optimized squeezing parameters were presented as follows: holding temperature of 570~630°C, both mould and pouring system heated to 150~250°C, punching velocity of 5~10 mm/s and pressure of 30~100 MPa for 40~120 s. The results show that the microstructure of the worm gear is obviously refined, and the mechanical properties are increased greatly, meanwhile the quality of zinc alloy worm gear is controlled effectively. Compared with those of permanent mold casting worm gear, tensile strength and elongation of the squeezing casting worm gear are improved by 100 MPa and by 139%, respectively.


Zhu Q.-L.,South China University of Technology | Xia Y.,South China University of Technology | Chen J.-J.,Guangdong Huajin Advanced Alloys Industrial Company Ltd | Wu Z.-Y.,South China University of Technology
Zhuzao/Foundry | Year: 2016

Al-5Ti-1Band RE were used in modification of the ZA27 alloy, and then the inclusions in the ZA27 alloy were studied, by using optical microscopic and SEMexamination, energy spectrum analysis (EDS) and X-ray diffraction (XRD). The results showthat rare earth elements and Fe elements are segregated at the grain boundaries, and formcomplex compounds with Zn, Al and Cu in ZA27 alloy. The compounds rich in rare earth are polygonal blocks, containing a large amount of rare earth elements, also containing Zn, Al and Cu, and may contain Ti; the compounds rich in iron aremainlyneedles, and a feware small pieces, consists of Zn, Al, Cu and Fe, not containing rare earth elements, and the average content of Fe is more than 20wt.%. These intermetallic compounds have fragmentary effect on the body, easy to produce stress concentration, leading to formation of micro-cracks andextensions. © 2016, Chinese Mechanical Engineering Society. All right reserved.


Zhu Q.-L.,South China University of Technology | Chen J.-J.,South China University of Technology | Li W.,South China University of Technology | Liu T.-Q.,South China University of Technology | Wang G.-L.,Guangdong Hua Jin Advanced Alloys Industrial Co.
Zhuzao/Foundry | Year: 2011

The oxidation kinetics at 960°C of RTCr28Ni15 and RTCr18Ni4 used for grate in garbage incinerator were studied by weight gain method. The microstructure, cross section, composition and the oxidation resistance mechanism of these two alloys' oxidation films generated after heating at 960°C for 100 h were analyzed by using of XRD, SEM and EDS. The results show that both the oxidation curves of RTCr28Ni15 and RTCr18Ni4 increase fast at the first stage and then slow down, but the oxidation rate of RTCr18Ni4 is faster than RTCr28Ni15. There is no protective oxidation film that forms on surface of RTCr18Ni4, so its oxidation resistance at 960°C is weak. However RTCr28Ni15 is totally oxidation resistant at 960°C due to the protective oxidation film formed on its surface and its oxidation resistance is superior to RTCr18Ni4.


Zhu Q.-L.,South China University of Technology | Zhang X.-M.,South China University of Technology | Chen W.-P.,South China University of Technology | Li W.,South China University of Technology | And 2 more authors.
Cailiao Kexue yu Gongyi/Material Science and Technology | Year: 2012

A novel lead-free brass containing P and Ca instead of Pb, whose over-all properties were excellent, was prepared by casting. Its cutting deformation mechanism was investigated by lathe turning experiment, and the cutting deformation was studied by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) in combination with Griffith theory of brittle fracture and cutting mechanics calculation. Results show that the cutting performance of P-Ca brass is good, the size and appearance of chips are the same as those of HPb59-1. Intermetallics distributed in grain boundaries cut off the continuity of matrix, during cutting, it fractures or falls off after deformation, even some melt because of the cutting heat, which cause sress concentration of matrix, lead to crack initiating and expensing, then the periodic shear bands slip to the free surface of chips into lamella structure, resulting in the fracture of chips and improving the cutting property. The properties of P-Ca brass is excellent, it is feasible to develop a new lead-free free-cutting brass containing P and Ca.


Zhu Q.L.,South China University of Technology | Wu Z.Y.,South China University of Technology | Chen J.J.,Guangdong Hua Jin Advanced Alloys Industrial Company Ltd
Materials Science Forum | Year: 2015

Compared with permanent mold casting, the microstructure, mechanical properties, friction and wear of squeeze casting ZA27 alloy were studied. The results showed that squeeze casting can reduce or eliminate shrinkage porosity defect, refine or improve the microstructure and the shape and distribution of copper-rich ε phase which leads to the obvious improvement of the performance. In addition, with the increase of solution temperature, higher degree of super-saturation can enhance the tensile strength and hardness of ZA27 alloy. The better deformation coordination is an important factor to the enhancement of elongation. Remelting among grain boundaries leads to the deterioration of performance rapidly. © (2015) Trans Tech Publications, Switzerland.


Zhu Q.-L.,South China University of Technology | Zhang X.-M.,South China University of Technology | Luo L.-S.,Guangdong Hua Jin Advanced Alloys Industrial Company Ltd | Li W.,South China University of Technology | And 3 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2012

The ingots of P-Ca brass were prepared in a medium frequency induction furnace through scientific casting process. The microstructure and mechanical, cutting and dezincification corrosion-resistance properties of P-Ca brass were studied by scanning electron microscopy (SEM), energy dispersive spectrometer(EDS), electron universal test machine and lathe, the effect of the intermetallics on the cutting performance was also studied through the observation of chips. The results show that, P and Ca change the microstructure and properties of brass alloys significantly, making the microstructure of P-Ca brass composed of α, β and intermetallic compounds dispersed on grain boundaries and in grains. The reasonable contents (mass fraction) of main elements are 57%-60% Cu, 40% Zn, 0.7% P and 0.5% Ca. The brass alloy containing this component has good performances as follows: tensile-strength of 362.7 MPa, elongation of 15.0%, Brinell hardness of 105.0HB, dezincification depth of 321.9 μm, and the cutting property is as well as that of HPb59-1.


Zhu Q.,South China University of Technology | Zhang X.,South China University of Technology | Chen J.,South China University of Technology | Chen W.,South China University of Technology | And 3 more authors.
Tezhong Zhuzao Ji Youse Hejin/Special Casting and Nonferrous Alloys | Year: 2010

Hard spots in high strength and wear resistant aluminum brass components were investigated systematically by optical microscope, scanning electron microscope and EDS, micro-hardness testing. Origination of the hard spots in the aluminum brass parts was described, and countermeasures were presented.

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