Papers by Author: Biao Wu

Abstract: In this study, 8009 heat resistant aluminum alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the alloy were studied using transmission electron microscopy, X-ray diffraction, and tensile tests. The secondary phases in the microstructure of the spray-deposited alloy were examined. The tensile test results indicate that the spray-deposited 8009 alloy both at room and elevated temperature displays superior tensile strength due to the presence of the thermally stable Al₁₂(Fe,V)₃Si particles.

Abstract: Heat-resistant FVS0812 alloys were prepared by spray forming technique. The effect of temperature on microstructure the alloys was studied by optical microscope (OM), transmission electron microscope (TEM) with energy dispersive spectrometer (EDS), differential scanning calorimeter (DSC) in this paper. The research results show that the microstructure of the material doesnt change obviously after being hold for 3 hours at 420°C temperature. When the temperature is over 420°C, the second coarse phases are found in the alloy. The studies on the microstructure of the alloy exposed at 400°C for 100 hours show that the alloy has excellent high temperature stability.

Abstract: Cold rolling rules according to the fixed incoming crown distribution of each crown control, raw material convexity fluctuations will destroy convex degree program, light is left with the residual stress, heavy waves. This paper discusses test incoming convexity, convexity control allocation method of residual stress.

Abstract: Heat-resistant Al-Fe-V-Si aluminum alloys enhanced by in-situ TiC particles have been prepared by spray forming process with suitable process parameters. Research results show that the microstructure of as-deposited alloy is fine and homogeneous. In-situ TiC particles prevent the unsteady phases from coming into being. On the other hand, the TiC particles increase the volume fraction of heat-resistant phases. So the mechanical properties of the enhanced alloy by in-situ TiC particles are better than that of Al-Fe-V-Si alloy without TiC particles. The hot extrusion temperature is also an important parameter to understand. Under the permission, it is better to extrude the alloy at lower temperature. The tensile strength of the alloy without TiC particles is about 435MPa at room temperature and is about 204MPa at 350°C. However, when the alloy is enhanced by in-situ TiC particles, the strength of alloy is about 482MPa at room temperature and is about 224MPa at 350°C temperature.

Abstract: In order to explore the effect of cryogenic treatment on creep resistance of Cu-11.74Al-0.38Ni alloy at room temperature, the room temperature creep deformation of Cu-11.74Al-0.38Ni alloy before and after cryogenic treatment at different applied load and time were measured by nanoindention technique, and the products were also characterized by optical microscope. The results show that cryogenic treatment can refine the grains, and reduce creep deformation of the alloy, which can improve the creep resistant properties of Cu-11.74Al-0.38Ni alloy effectively.

Abstract: The microstructure, compressive fracture morphology and compressive strength of aluminum bronze before and after cryogenic treatment were observed and measured by OM, SEM and electron universal testing machine, and the effect of cryogenic treatment on compressive properties of aluminum bronze were investigated. The results show that cryogenic treatment can reduce the compressive strength of aluminum bronze, and after cryogenic treatment and at 600°C for 5min, its compressive strength is increased. And the microstructure of aluminum bronze has a good correspondence with its compressive strength.

Abstract: Al-Zn-Mg-Cu alloy was 3GPa pressure treated, and the effect of high pressure treatment on nanoindentation creep property of Al-Zn-Mg-Cu alloy was investigated by using nanoindentation. The results show that indentation creep in Al-Zn-Mg-Cu alloy before and after 3GPa pressure treatment can occur at room temperature, 3GPa pressure treatment can reduce creep deformation of Al-Zn-Mg-Cu alloy at room temperature at different pressure and time, and leads to the creep resistance of Al-Zn-Mg-Cu alloy rises.

Abstract: The temperature and duration of β1→α+β2 transformation of Ti-6Al-4V alloy in cooling process were measured by differential scanning calorimetry, and transformation activation energy and Avrami exponent of β1→α+β2 were also calculated. The results show that the cooling rate is in the range of 在5～20°C/min, the transformation temperature and the transformation duration β1→α+β2 transformation of Ti-6Al-4V alloy decreased with the increasing cooling rate, its transformation activation energy decreased with the increasing phase transformation volume fraction, and Avrami exponent was between 1 and 2 at 660°C.

Abstract: The Cr18 - Mn18 steel was prepared by the high temperature and high pressure reaction kettle. With bottom blowing time and bottom blowing flow as object to do single factor experiment, the relationship between the nitrogen content in steel smelting process and the bottom blowing time, the bottom blowing flow were studied.The research results show that when the other conditions must be, the nitrogen content in steel increases with the bottom blowing time increasing gradually, when the bottom blowing time reach more than 35 min, the variation of nitrogen content in steel decreases. With the increase of bottom blowing flow rate, the nitrogen content in steel increases gradually, when the bottom blowing flow rate reaches more than 0.24 m3/h, the nitrogen content in steel close to the maximum value and does not change with bottom blowing flow rate.

Abstract: In this study, nitrogen content greater than 0.9% of 18Cr18MnN austenitic stainless steel were prepared by high pressure reaction kettle. The relationships between nitrogen content and temperature, pressure were studied. The results show the nitrogen content in steel increases with increasing melting pressure, at air pressure 1.0MPa<P<1.4MPa, the increase of nitrogen content in steel is evident particularly. In the 1813k<T<1913k temperature range, the nitrogen content in steel decreases with the increasing temperature, there are differences in variation in the temperature range. When temperature is up to 1813K, nitrogen content can be as high as 1.075%. The best thermodynamic condition of melting a nitrogen content of 0.9% 18Mn18Cr austenitic stainless steel is: pressure and temperature are 1.32MPa, 1873k, respectively.