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Dong Z.,Harbin Institute of Technology | Ma R.,Harbin Institute of Technology | Wang Y.,Shanghai Xin Li Institute of Power Equipment | Zhan X.,Nanjing University of Aeronautics and Astronautics | And 2 more authors.
Hanjie Xuebao/Transactions of the China Welding Institution | Year: 2011

A software package has been developed which can simulate and predict the weld solidification cracks with three dimensional FEM. It consists of pre-processing, post-processing and solidification cracks predicting subsystem. The post-data treatment of software package for three-dimensional simulation and prediction of the weld solidification cracks can deal with the calculated results and display the results in featured curves, contours and 3D figures by combining graphic functions of softwares. The solidification cracks predicting subsystem regresses to the experimental data of trans-varestraint test (TVT) to obtain the material resistance curve of weld solidification cracks or reads the modified material resistance of simulating TVT from the database and has it compared with the one and thus predict the weld metal solidification cracks. Source

Zheng W.,Harbin Institute of Technology | Dong Z.,Harbin Institute of Technology | Wei Y.,Nanjing University of Aeronautics and Astronautics | Wang Y.,Shanghai Xin Li Institute of Power Equipment
Crystal Research and Technology | Year: 2014

A computationally efficient quantitative phase field formulation is used to investigate the sidebranching dynamics under different transient conditions in directional solidification for realistic parameters of a dilute alloy. The sidebranch growths where the pulling speed or temperature gradient increases with constant increasing rates are simulated and discussed by using the noise amplification theory. The results show that in transient growth, the tip shape can rapidly adjust with the instantaneous conditions, and the tip velocity changes continuously due to the change of tip undercooling. Therefore, under our given transient conditions, the sidebranch spacing or sidebranching frequency depends strongly on the transient conditions and transient history, which is different with that in steady-state conditions where the sidebranching frequency is found to be independent of the temperature gradient and primary spacing, but varies as a power law of pulling speed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Yu H.-J.,Shanghai JiaoTong University | Fan R.-Y.,Shanghai Xin Li Institute of Power Equipment | Huang J.,Shanghai JiaoTong University | Pan L.-H.,Shanghai Xin Li Institute of Power Equipment | Wang Y.,Shanghai Xin Li Institute of Power Equipment
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2015

The titanium alloy TC11 was welded by fiber laser beam, the microstructure and mechanical properties of the laser welded TC11 joints with different welding parameters were studied. The results show that the microstructure of weld metal consists of α' martensite. From the base metal to fusion line, the microstructure evolves from α +β phase to α' phase. With increasing the heat input, the size of columnar dendrites increases, the distribution of α' martensite becomes more dispersive, the width of HAZ and grain size in coarse grain zone increase. Under the welding speed of 2.0 m/min and laser power of 2.8-3.2 kW, the sound welds of 2 mm thick TC11 alloy were obtained. The hardness of the weld increases with increasing the heat input. The tensile strength of welded joints reaches at least 97% of that of the base metal, while the plasticity decreases significantly. The fracture topography of welded joints shows brittle fracture character. ©, 2015, Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals. All right reserved. Source

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