Applied Mechanics and Materials Vols. 633-634

Abstract: In the midst of highly corrosive marine environment the corrosion damage is very critical in the aircraft structure. Corrosion will reduce the fatigue strength and fatigue life of aircraft structure. The fatigue notch factor is a very important factor, and which directly affects the accuracy of the fatigue life estimation result. The LY12CZ aluminum alloy of aircraft structure was accelerated tested according to equivalent accelerated corrosion testing spectrum based on key environment data, then made a fatigue test. According to the fatigue test data fatigue notch factor was calculated and then the variation law of fatigue notch factor with the corrosion life was studied.

Abstract: This article study the dynamic fracture behavior of compact tension specimens under tensile wave loading ^[1-3]. And the test - numerical hybrid method is used to satisfy the condition of dynamic stress equilibrium. The initial load for numerical simulation is based on the experimental data. In that case, the numerical simulation results can be used to analysis the dynamic stress equilibrium.

Abstract: Titanium concentrate mainly contains the elements, Ti, Fe, Si, Ca, Mg, Al, P, S, Ba, Zr and etc, by XRF. Its original main phase was very likely FeTiO₃ by XRD. After treated at 673K for 10h, the phases had only slightly changed, with a little weight gain (about 0.32%). After treated at 1273K for 10h, its phases had been changed to very complex solid solutions, which may contain Fe₂TiO₅, Fe₃Ti₃O₁₀, TiO₂ (rutile), Fe₂O₃ and etc, with an obvious weight gain (about 3.35%). The phase change may be caused by the reaction of titanium concentrate with oxygen. Obvious relative loss of the main elements was found during heat treatments especially sulfur. Most of sulfur had been volatilized during the heat treatment at 1273K. It may be conducive to better development and utilization processing of titanium concentrate.

Abstract: Steel ladle is the indispensable vessel of transporting and refining molten steel. In order to realize efficient control of steel ladle and optimize the production organization of steelworks, the operational control model of steel ladles should be proposed. Based on steel ladles of Z steelwork as the research object, operation mode and turnover cycle of steel ladle were analyzed. Through drawing out steel ladle Gantt chart of single continuous caster and analyzing operation characteristics of steel ladle, calculation model of turnover number and rotation ratio of single continuous caster was put forward. Through drawing out steel ladle turnover Gantt chart of 3 continuous casters and analyzing mixed use characteristics of cast overlap time greater than, less than, and in between steel ladle turnover cycle of 3 continuous casters, the operational control model of steel ladles was put forward. Researches show that the model can effectively reduce amount of steel ladle turnover number and raise steel ladle rotation ratio when casting heat number of CC is less than steel ladle turnover number during the overlap time.

Abstract: The chemical composition and production process of a new kind of enameling steel sheet used for heat-exchanger were introduced. The microstructure, mechanical property and hydrogen permeation resistance of the steel sheet were studied. The enameling adherence and pin-hole ratio of the enameled steel sheet were measured. The results show that the microstructure is ferrite with the grain size of grade 11 and quantities of linear MnS inclusions, grainy manganese-niobium composite oxides and small NbC precipitates are formed in the steel. The average value of hydrogen permeation resistance of the steel is 33 min·mm^-2, the enameling adherence is evaluated as level A1and the number of the pin-hole defects in the enameled steel is less than 10 per square meter. Both mechanical property and enameling quality of the steel sheet meet the technical demand of heat-exchanger.

Abstract: The mechanical properties and microstructures of three different VN, Nb, V-Nb microalloyed rebars were investigated by using tensile testing machine, impact machine, metallographic microscopy, scaning electron microcopy, transmission electron microscopy and X-ray diffraction apparatus. The results showed that the microstructure of V-Nb microalloyed specimen is consisted of ferrite, pearlite and a small amount of fine bainite (6.7wt%), and obvious effect of grain refinement was obtained with more than 10 size grade of ferrite grain, showing optimal comprehensive properties. SEM micrograph of tensile fracture surface for V-Nb microalloyed 500MPa high-strength rebar is dimple and ductile, ductile-brittle transformation temperature is lower than-30°C, which has good plasticity-toughness and impact toughness at low temperature. The results of precipitates have shown that a large number of small and dispersive V(CN) and Nb (CN) precipitates with size of 5~30nm are formed, good effect of precipitation strengthening was achieved in 500MPa high-strength rebars produced by different microalloying and controlled cooling technology.

Abstract: The effect of power and radiation time on inclusion removal was studied in the ladle refining cold model by using organic particles to imitate inclusion. We simulate ultrasonic agitation in the ladle refining model by programming user-defined functions with the FLUENT computational fluid dynamics software. Results show that a large negative-pressure zone is observed in the liquid of the dynamic boundary during the first time step. During the second time step, the liquid at the bottom of the model has a large positive pressure area. Inclusions in the molten steel should be removed through pressure change to improve the purification effects of liquid steel. As the power increases, the absolute value of negative pressure increases.

Abstract: A series of air knife flow rate were conducted by a hot dipping process simulator in laboratory to study its effect on coating weight and thickness. The research results show that, when the experimental steel were immersed for 3.5s in a Zn-0.24%Al zinc bath, with atmosphere of N₂-10%H₂ and dew point-60°C in the whole simulation, air knife flow rate (FR) was a key factor for coating surface quality. When FR was precisely controlled by the simulator from 200~500 l/min, the coating weight and thickness decreased significantly from 159.68 to 56.19 g/m² and 17.45 to 7.84 μm. In which the decreasing line was more obvious when FR increased from 300 to 400 l/min, that the coating thickness had a dramatic decreasing from 18.08 to 11.07μm.

Abstract: The analysis of the residual life of high temperature low cycle fatigue of 30CrMnSiA steel plays important roles in improving security and avoiding accidents. In this paper, the RBF neural network method is used to predict the residual life of high temperature low cycle fatigue of 30CrMnSiA steel base on data from the thermo-mechanical fatigue test. The feasibility of the method is proved by a practice example, and the learning results are in good agreement with the experimental data.

Abstract: A thermodynamic model of calculation of sulfur distribution ratio between B₂O₃-containing slag and molten steel has been developed on the basis of the ion and molecule coexistence theory. Based on the model, the effects of B₂O₃ content and slag basicity on the sulfur distribution ratio in 1873K were investigated respectively. The results indicate that the sulfur distribution ratio decreased with increasing the content of B₂O₃, and when the content of B₂O₃ exceeds 6%, the sulfur distribution ratio was lower than 2.0. Therefore, in order to ensure the desulphurization ability of slag, the content of B₂O₃ should be controlled at about 6%. Moreover the sulfur distribution ratio can be increased by increasing the slag basicity.