By using the finite element method(FEM), we comprehensively analyzed the fields of temperature, organization, and stress in 35CrMo train axles during the quenching process is conducted, and experimentally studied the formation and evolution of inner stresses in axles during the quenching process. The results show that in the quenching process, stresses on the axle surface change from tensile to compressive gradually, while stresses in the axle core change from compressive to tensile gradually. Heat stresses and the amount of martensitic transformation are all increased with the increase of cooling rate. As a result, the maximum instantaneous stresses in the axle are increased greatly when the cooling rate is increased with brine quenching. Large instantaneous tensile stress in the axle core with brine quenching is very likely to cause quench cracking and should be avoided.
In order to study the distribution of equivalent and shear strain of aluminum alloy plate during snake hot rolling, several coupled thermo-mechanical finite element models(FEM) are established. Effects of speed ratio and offset distance on strain distribution of the plate are analyzed. The length of cross shear zone is defined to have a better understanding of the deformation characteristic in cross shear zone, which is the essential difference from symmetrical rolling in deformation zone. The results show that the equivalent strain and shear strain of lower part both increase with the increase of speed ratio, while the upper part decreases; the equivalent strain through the whole thickness decreases with ascending offset distance, while the shear strain of lower part increases. The length of cross shear zone quickly increases with ascending speed ratio and slightly decreases with ascending offset distance. The "positive" and "negative" cross shear zones are formed with the increase of speed ratio and offset distance, respectively. The value of the sensitivity coefficient of speed ratio is an order of magnitude bigger than the offset distance. However, the shear strain at center point increases with the ascending speed ratio and offset distance for different mechanism. As speed ratio increases, the asymmetry of the distribution of equivalent is becoming larger and the shear strain is generated in the same direction in cross shear zone. The FEM results agree well with experimental results.
The interfacial reaction between aluminum melt and molten slag under an electric field plays a significant role in aluminum electro-slag refining. Here we studied this interfacial reaction within 680 and 820 ℃ under an electric field between 0 and 9 V. The evolution of aluminum composition was analyzed by inductively coupled plasma atomic emission spectroscopy. The dominant factor during the interfacial reaction was identified through orthogonal experiments, in which the slag-to-aluminum mass ratio, initial silicon concentration, electric voltage, reaction time, and temperature were selected as the influence factors. The greatest influence factor on the interfacial reaction was found to be the reaction time. Also,single-factor experiments revealed that the reaction kinetic processes largely obeyed an irreversible kinetic model, and the silicon removal efficiency was enhanced by increasing the voltage and slag/metal ratio.
