Yixiong Wu
Shanghai Jiao Tong University
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Publication
Featured researches published by Yixiong Wu.
Journal of The Mechanical Behavior of Biomedical Materials | 2017
Jianjun Lin; Yaohui Lv; Yuxin Liu; Zhe Sun; Kaibo Wang; Zhuguo Li; Yixiong Wu; Binshi Xu
Plasma arc additive manufacturing (PAM) is a novel additive manufacturing (AM) technology due to its big potential in improving efficiency, convenience and being cost-savings compared to other AM processes of high energy bea\m. In this research, several Ti-6Al-4V thin walls were deposited by optimized weld wire-feed continuous PAM process (CPAM), in which the heat input was gradually decreased layer by layer. The deposited thin wall consisted of various morphologies, which includes epitaxial growth of prior β grains, horizontal layer bands, martensite and basket weave microstructure, that depends on the heat input, multiple thermal cycles and gradual cooling rate in the deposition process. By gradually reducing heat input of each bead and using continuous current in the PAM process, the average yield strength (YS), ultimate tensile strength (UTS) and elongation reach about 877MPa, 968MPa and 1.5%, respectively, which exceed the standard level of forging. The mechanical property was strengthened and toughened due to weakening the aspect ratio of prior β grains and separating nano-dispersoids among α lamellar. Furthermore, this research demonstrates that the CPAM process has a potential to manufacture or remanufacture in AM components of metallic biomaterials without post-processing heat treatment.
Tribology Transactions | 2015
Feng Nan; Yi Xu; Binshi Xu; Fei Gao; Yixiong Wu; Zhuguo Li
This study investigated the effect of Cu nanoparticles on the tribological properties of attapulgite base grease. It was found that the friction reduction ability and antiwear property of the base grease can be improved with the addition of Cu nanoparticles. Under the lubrication of grease containing Cu nanoparticles, a smoother and more compact tribofilm was formed on the rubbing surface. The tribofilm is mainly composed of Cu, FeO, Fe2O3, FeOOH, CuO, and SiO. In addition, the content of iron oxides and silicate oxide formed in the tribofilm was increased by the introduction of Cu nanoparticles.
Advances in Materials Science and Engineering | 2013
Dingjian Ye; Xueming Hua; Yixiong Wu
In order to study arc interference behavior during twin wire gas metal arc welding process, the synchronous acquisition system has been established to acquire instantaneous information of arc profile including dynamic arc length variation as well as relative voltage and current signals. The results show that after trailing arc (T-arc) is added to the middle arc (M-arc) in a stable welding process, the current of M arc remains unchanged while the agitation increases; the voltage of M arc has an obvious increase; the shape of M arc changes, with increasing width, length, and area; the transfer frequency of M arc droplet increases and the droplet itself becomes smaller. The wire extension length of twin arc turns out to be shorter than that of single arc welding.
Welding in The World | 2017
Dingjian Ye; Dongsheng Wu; Xueming Hua; Chen Xu; Yixiong Wu
Three-dimensional numerical models are established to investigate the convection in multi-wire GMAW processes. A high-speed photography system is used to capture the transient images of the weld pools. Based on the simulation and experimental results, the humping formation and suppression mechanisms are discussed. The results show that both the “push-pull” and outward flow patterns exist in the multi-wire GMAW weld pools, which help decrease the momentum of the backward fluid flow and widen the weld width. In high-speed GMAW process, there are three main factors that cause the formation of humping: the high momentum of the backward fluid flow, the capillary instability, and the large variation of the capillary pressure of the liquid channel in the welding direction. In twin-wire GMAW process, the first two factors are suppressed, humping is disappeared, but the variation of the capillary pressure of the liquid channel in the welding direction is still large, which causes the weld width uneven. All of those three factors are suppressed in triple-wire GMAW process, so sound weld bead can be obtained; the distance between the middle wire and trailing wire has little influence on the weld bead formation.
Journal of Materials Engineering and Performance | 2017
Gang Li; Xiaofeng Lu; Xiaolei Zhu; Jian Huang; Luwei Liu; Yixiong Wu
The segregation and liquation crackings in the heat-affected zone (HAZ) beside Inconel 52M overlays of multipass laser-welded joints are investigated for nuclear power plants. The results indicate that Nb-rich precipitates are distributed in chains and some aggregate together as coarse particles in the local regions at the interface. With increasing heat input, the transition width becomes widened and the fraction of the precipitates at the interface significantly increases. Closely associated to Nb segregation, liquation crackings occur along columnar dendrites in the HAZ beside Inconel 52M overlays. Due to no deformation coordination of the columnar dendrites with Nb-rich segregates in Inconel 52M overlays, liquation crackings occur in thermal cycle of multipass laser welding. The enrichment of Nb element in the interdendritic regions increases favorable factors of liquation crackings at grain boundaries.
Journal of Materials Engineering and Performance | 2016
Lyuyuan Wang; Jian Huang; Zhuguo Li; Jie Dong; Yixiong Wu
The microstructure and mechanical properties of laser-welded high-strength Mg-Gd-Y-Zr alloy in T6 condition were investigated. The network-distributed precipitates at grain boundaries were identified as the Mg24(Gd,Y)5. No significant grain coarsening was observed in the heat-affected zone. The deterioration of mechanical properties was attributed to the dissolution of precipitates in the heat-affected zone during laser welding. For the weakest part of the heat-affected zone, solid solution strengthening was the most important strengthening factor.
Journal of Materials Engineering and Performance | 2013
Jun Dai; Jian Huang; Zhuguo Li; Jie Dong; Yixiong Wu
The effects of heat input on the quality of laser-welded Mg-rare earth alloy NZ30K were studied. Using a 15-kW high-power CO2 laser, the microstructure and mechanical properties of welded joints under different heat inputs had been analyzed and tested. It is found that the welding heat input plays an important role in laser welding of NZ30K. Good welded joint without macroscopic defects can be obtained using the proper heat input. With the increasing heat input, welding penetration gets deeper, the width of the heat-affected-zone becomes larger, and the distribution of precipitates changes concentration. Tensile tests display that the ultimate tensile strength (UTS) of the welded joint tends to increase at first with the increasing heat input. After the welded joint gets full penetration, the UTS remains almost the same, although the heat input is increased.
International Journal of Materials Research | 2012
Jun Dai; Jian Huang; Zhuguo Li; Jie Dong; Yixiong Wu
Abstract The welding processes of three different magnesium alloys ZK60, AZ31, and Mg-rare earth alloy NZ30K were studied using a high-power CO2 laser. The microstructure and tensile strength of welded joints were tested and analyzed. With increasing welding speed the tensile strength and total elongation of welded joints of ZK60 alloy are improved. The ultimate tensile strength of the welded joint of ZK60 is 211.18 MPa, 90% of the base metal. The tensile strengths of welded joints of AZ31 and NZ30K are better than those of the base metal. The expansion of the plasma of laser-welded ZK60 is the strongest with the highest temperature.
Materials | 2017
Yanbing Guo; Chengwu Yao; Kai Feng; Zhuguo Li; Paul K. Chu; Yixiong Wu
The growth and propagation behavior of austenite-to-bainite isothermal transformation in laser-cladded, Si-rich, and Fe-based coatings is investigated. The crystallographic features, orientation relationship at different isothermal temperatures, and the morphology of the nanostructured bainite are determined. The Nishiyama-Wassermann type orientation relationship is observed at a high temperature and at a low temperature, and mixed Nishiyama-Wassermann and Kurdjumov-Sach mechanisms are seen. The growth direction is investigated by the partial dislocation theory and an extrapolated model based on the repeated formation of lenticular-shaped subunits and pile-up along the close-packed directions of the close-packed planes. The variants of the bainite growth directions would be more selective at the high transformation temperature.
International Photonics and Optoelectronics Meetings (2012), paper MF3B.3 | 2012
Zhuguo Li; Chengwu Yao; Yanyan Zhu; Jian Huang; Yixiong Wu
Three types of Fe-based coating for high hardness, including low-temperature bainitic coating, particle reinforced martensite coating and amorphous coatings, have been prepared on mild steel by using high power diode laser cladding.