Papers by Author: Juan Hua Su

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Authors: He Jun Li, Juan Hua Su, Qi Ming Dong, Ping Liu, Feng Zhang Ren
Abstract: The aging process of lead frame Cu-Cr-Sn-Zn alloy has only been studied empirically by trial-and-error method so far. This paper builds up the prediction model of the aging properties via a supervised artificial neural network(ANN) to model the non-linear relationship between parameters of aging process with respect to hardness and electrical conductivity properties of the alloy. The improved model is developed by the Levenberg- Marquardt training algorithm. The predicted values of the ANN coincide with the tested data. So the ANN system is effective and successful for predicting and analyzing the properties of Cu-Cr-Sn-Zn alloy. The optimized processing parameters are available at 475 C ° -520 C ° aging for 2h-1h.
Authors: Feng Zhang Ren, Jun Tao Zhang, Qiu Ran Gao, Yao Min Zhu, Juan Hua Su
Abstract: The hot deformation behavior of Mg-3.5Zn-0.6Y-0.5Zr alloy was investigated by compressive tests of strain rate ranges of 0.002~1 s-1 and deformation temperature ranges of 300~450 °C using a Gleeble 1500D thermal simulator. The flow stresses in different deformation conditions are measured. The results show that flow stress is significantly affected by both deformation temperature and strain rate, the flow stress increases with increase in strain rate and decreases in deformation temperature during the hot compression process. The constitutive equation established on the basis of data of activation energy and stress exponent is a hyperbolic sine function.
Authors: Juan Hua Su, Shu Guo Jia, Feng Zhang Ren, Ping Liu, Bao Hong Tian
Abstract: The effects of different extent of cold rolling on the aging properties in Cu-Cr-Sn-Zn alloy are investigated by hardness and electrical conductivity analysis and microstructure TME (transmission electron microscopy) observation of the alloy. The results shows that dislocations provide nucleation site for precipitation during aging treatment, and result in the precipitation hardening effect from a finer size of precipitates. At 60% ratio of cold rolling and aged at 450°Cfor 1h, the hardness and electrical conductivity can reach 171.3HV and 71.5%IACS respectively.
Authors: Qi Ming Dong, Ping Liu, Juan Hua Su, He Jun Li, Bao Hong Tian
Abstract: By using the finite element method and large strain two-dimension plane strain model, the flaking damage of Cu-Fe-P lead frame sheet is investigated. The characterization of microstructure under surface flaking is the larger Fe particles embedded in the copper matrix. The numerical analysis reveals that at the interface of Cu and Fe there are greater strain mutation and intense stress concentration that is increased with particle diameter and the extent of deformation. This strain and stress concentration makes the interface initiate crack and develop crack easily. The micro-crack around the Fe particle is also attributed to surface flaking damage under the finish rolling deformation. The larger Fe particles should be avoided in the production of Cu-Fe-P alloy.
Authors: Juan Hua Su, Feng Zhang Ren, Lei Wang
Abstract: This paper analyzes the forming process methods of fin used in CPU chip to emit heat. The whole process is blanking, the first forging forming, the second forging (sizing), and trimming. The chamfer design of CPU fin blank is simulated by finite element analysis. The optimized chamfer 1.6 mm is available. Semi-enclosed cold forging of progressive dies is put forward. The newly designed transfer unit is applied, which unifies the merit of high efficiency of the progressive dies and the high material-using ratio of the project die. Quick disassembly structure is designed and pins are used as quick disassembly pins by means of ball bearing bushing. The unique processing of the shearing scrap structure is adopted when designing the inverted trimming dies. Compared with the traditional die, the mechanization and electrization are realized to increase the production efficiency and get highly precise CPU fin.
Authors: Juan Hua Su, Feng Zhang Ren, Ze Yang
Abstract: The bending performance of lead frame materials is a very important in improving the quality of lead frame alloys and meeting the needs of high performance integrated circuit. The sringback amount of curvature variation of CuFeP , CuCrZrMg , CuNiSi and CuCrSnZn alloy are researched by numerical simulation. Bending model is built by 3D modeling software, and the necessary post-processing is carried out. The bending springback amount △K of the four kinds of copper alloy materials are calculated out. The results show that the sringback amount of curvature variation of four copper alloys at the same condition from large to small in turn is CuCrZrMg, CuNiSi, CuFeP, CuCrSnZn. Smaller the minimum relatively bending radius of copper alloy used in lead frame, less the springback amount and better the forming performance.
Authors: Xiao Hong Chen, Yan Li, Bao Hong Tian, Yi Zhang, Juan Hua Su, Ping Liu
Abstract: A method of the aluminizing treatment on the surface of Cu-Al-Y alloy with addition of rare earth compound CeCl3 in 1173K was carried out. The followed internal oxidation of the aluminized Cu-Al-Y alloy was also carried out in the commercial nitrogen gas medium to generate Al2O3 dispersed hardening copper matrix composites. The hardness distribution in aluminized layer and microstructure were studied. Results show that the addition of rare earth oxide CeCl3 has great accelerating effect on the aluminizing, the aluminized layer deeper and uniform than that not add CeCl3 at the same condition. It is possible to generate Al2O3 particles dispersed hardening layer depth reached about 200μm in the surface of specimens with aluminizing and internal oxidation technique.
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