Feng Kang

Microstructure and tensile properties of AM50A magnesium alloy prepared by recrystallisation and partial melting process

Prior to thixoextrusion, the microstructural evolution of semi-solid AM50A magnesium alloy prepared by the recrystallisation and partial remelting (RAP) route was investigated. The effect of compressive ratio on microstructure of semi-solid AM50A magnesium alloy was studied. Furthermore, tensile properties of thixoextruded components were determined. The results showed that the occurrence of recrystallised grains was closely associated with the location of the first liquid formed above the solidus. With prolonging holding time, deformed microstructure was penetrated, causing fragmentation, which resulted in the decrease of average grain size. Moreover, prolonging holding time was favorable for the improvement of the degree of spheroidization due to the increase in the amount of liquid. With the increase in compressive ratio, the size of solid grain decreased, the degree of spheroidization was improved during partial remelting, and the tensile properties of thixoextruded AM50A components were improved. The tensile properties for AM50A magnesium alloy thixoextruded from starting material produced by the RAP route were better than those of the same alloy produced by die-casting and thixomolding.

Influence of the Deformation Parameters of a Low-cost Titanium Alloy on Structure

By the research in the thermodynamic simulation of a new kind of low-cost Titanium alloy-Ti8LC, The temperature, speed and degree were studied to prove what infection it take to the Micro-structure. The test make clear that the influence of temperature was the most important parameter to the alloy, when it under 1000°C, it appears two-state structure, it is propitious to the combination properties, and when it above 1000°C, it appears lamellar structure, holds high strength but low extensibility. Comprehensive consideration with the resistance to deformation, the velocity in the deformation cannot take too fast, and the degree adapted to 40%~60 %. This can gain favorable capability.1

Simulation and Experiment Study on Upsetting Process of Crankshaft

Aim at the bending and upsetting process of a kind of crankshaft, this paper analyze the technical difficulty and treatment measures during the process. The metal flowing and the defects easily occur during the deformation are visual reappeared by the FEM, moreover, the influence of the thickness of flash and the size of fillet on the quality of crank is also analyzed. Takes the crank as an object, the experiment of bending and upsetting deformation is carried on, which verified the accuracy of the simulation result, and finally, the crank is qualified with fullness deformation, continuous fiber without collapsing or folding. The product with this process can satisfied all the specification of the technology.

Study on the Cold Closed-Die Forging of Planetary Bevel Gears

Taking the Planetary Bevel Gears as an object, the characteristic of cold Closed-die Forging was studied. By Using the FEM, the flowing rule of metal in the process of cold forging were analyzed, which is composed of dual-direction extrusion, upsetting and filling the gear form. The results show that each district of cavity was filled completely at the end of forging, without corner collapse, fold or crack. Taken the lower die as an example, the distribution of die stress was also analyzed. The results of numerical simulation were proved by the experiments, meanwhile the high precision and quality forging was formed. To the gears, the cold closed-die forging can not only ensure the dimensional precision, but also improve the capability of the gear, while obviously reduce materials consumption.