Papers by Author: Gui Wang

Abstract: The improvement of machinability during thermally assisted turning of Ti-6Al-4V alloy was investigated by finite element modelling. A 2D thermally assisted turning model was developed and validated by comparing the simulation results with experimental results. Detailed analyses were carried out on the simulations in terms of the influence of the initial work-piece temperature on cutting forces and chip formation in the TAM process. The predicted cutting forces showed a very good correlation to the experimental results, and both the simulation and experiments have proved that the initial work-piece temperature plays an important role in determining the cutting force, with increasing initial temperature reducing the cutting force.

Abstract: Machining of Ti25Nb3Mo3Zr2Sn beta titanium alloy is carried out under two different heat treatments, solution treated, and solution treated and aged conditions. The chips formed after machining were cold mounted, polished and etched to reveal their microstructures. Different chip parameters such as average chip thickness, shear angle, undeformed chip length, and distance between serrations were measured and reported for both the heat treated samples for a wide range of cutting speeds, ranging from 5 m/min to 175 m/min. The results obtained were explained in terms of the heat treatment (hardness) of the samples and the cutting speeds.

Abstract: The experiment has studied the effect of solidification process of Fe-C-S alloy treated RE on the distribution of elements and inclusions on the distribution of elements and inclusions after the electric pulse field is applied. The results show that Rare Earth in the molten steel has played a purification role and change the strip MnS inclusions into spherical sulfide inclusions. Meanwhile, the co-action of electric pulse field and Rare Earth can reduce and refine inclusions and improve the distribution of elements in solidification microstructure.

Abstract: In this study the effects of different aging heat treatments on the properties and microstructure of a high strength, high toughness metastable β Ti, BTi-6554 (Ti-6Cr-5Mo-5V-4Al), have been compared. An initial β phase solution treatment was followed by aging at moderate temperatures in the α/β dual phase zone by either step aging directly from the solution treatment temperature or by quenching to room temperature prior to the aging heat treatment. The differing heat treatment methods have significant effects on the microstructure and mechanical properties.

Abstract: The effect of HIPping on the mechanical properties and microstructure of a cast Ti-6Cr-5Mo-5V-4Al alloy have been investigated. In the cast condition, the alloy predominantly consists of coarse β grains. In comparison to the HIPped samples, it exhibits poor mechanical properties, in particular low ductility, due to large amounts of remnant porosity. HIPping at 740°C substantially reduces the amount and size of porosity, while HIPping at 820°C and 900°C virtually eliminates all porosity, significantly improving the mechanical properties.

Abstract: Calcium oxide stabilized cubic zirconia powders were synthesized with electrochemical method using analytical reagent zirconium oxychloride and calcium oxide as the raw materials. From XRD analysis, zirconia powders doped calcium oxide are mainly being as cubic phase under the temperature lower than 1100°C. While the zirconia powders which did not doped calcium oxide were transformed from cubic phase to monoclinic phase when the powders were sintered at 750°C. The calcium oxide used as dopant in zirconia has two advantages, the first is that it can stabilize the cubic zircnnia, the second is that it can restrain the zirconia powders’ growing up.

Abstract: Pulsed electric field has been effectively used to control and modify the solidification process in castings. In this study, a pulsed electric field at 8 volts and 19 kHz has been applied to Fe-P, Fe-S, and Fe-Si binary alloys, and microstructure and elements distribution of the three alloy samples have been inspected. The results indicated that P migrated from cathode to anode while S and Si migrated from both electrodes to the center under the pulsed electric field during the solidification process.

Abstract: Three binary Fe-based alloys Fe-S, Fe-Si, and Fe-Mn has been designed and melted in order to investigate the effect of static magnetic field on the migration behavior and distribution of the three elements during the solidification process in this study, and microstructure and chemical composition on the samples have been inspected by optical microscopy and Original Position Analysis technologies. It has been found that the magnetic field can effectively change the distribution of S, Si and Mn, and the migration behaviors of the three elements are different.

Abstract: Molten, commercially pure aluminum has been treated ultrasonically with differing input power. The results show that the ultrasonic power can significantly refine the microstructure of the aluminium and increase the hardness of the samples. A mathematical model developed in this paper can predict the effect of the ultrasonic power on the grain size of the pure aluminium well.

Abstract: A pulsed electric current (19 kHz, 0-8 volts) has been applied to a molten Fe-0.5C-1.5Mn alloy to investigate its effect on the microstructure and the distribution of carbon and manganese. It has been shown that the pulsed electric field can improve the microstructure from a coarse banded structure to a compact acicular structure by increasing the pulsed voltage from 4 volts to 8 volts. The pulsed electric treatment also has an effect on the C and Mn distribution with a tendency for C and Mn to migrate to the cathode.