Advanced Materials Research Vol. 940

Abstract: The surface morphology and microstructure of galvannealed steel sheet (GA) coatings prepared at different galvannealing parameters were analyzed by X-ray diffraction and SEM, and powdering amount of GA coating was investigated by the double-Olsen powdering tester. The results show that when the Al contents below 0.16 wt%, the Ra of GA coating surface was measured namely below 1.0 μm, and powdering amount of GA coating was below 30 mg/m², it is within a reasonable value required by automotive makers. After that with the Al contents increased in zinc liquid the amount of powdering increased, this means that the powdering resistance performance of GA coating not only depended on the iron content in the coating, but depended on the roughness profiles of the surface coating. When the galvanizing coating with 0.22 wt% Al content and galvannealing at 500 °C, with the inhibition effect of Fe₂Al₅Zn_x inhibit layer, the thickness of δ_1k-phase was different in the GA coating, which deteriorated the powdering resistance performance of GA coating.

Abstract: This review paper mainly consists of from two aspects: (a) the evolution of the cavitation damage equation from Dyson to current application in high Cr steels by traditional techniques; (b) quantitation analyses of cavitation behavior in brass, copper, dual phase steel from X-ray microtomtograph. Though there is a lack of experimental data for high Cr steels by X-ray microtomography currently, but (b) has provided reference value for studying creep cavitation behavior in high Cr steels. This paper will be the fundamental of development new creep damage constitutive equation through quantitation analyses of X-ray tomography.

Abstract: The paper is to study the water treatment technologies for supercritical unit to improve its steam-water quality and ensure safe and economical operation. Based on lots of domestic and foreign literature and field investigation in some typical power plants, the paper summaries present situation and development prospects of the technology and system process of water treatment for supercritical unit, and also compared the technologies, including make-up water, condensate water and feed-water treatment, from theoretical and technical prospective.

Abstract: Sodium bicarbonate was modified with citric acid by solution coating method, and used to increase the foaming temperature and narrow the range of decomposition temperature. The thermodynamic parameters of sodium bicarbonate and modified sodium bicarbonate were studied by DSC and TG. After the modification, the initial decomposition temperature of sodium bicarbonate raised from 112.6 ^oC to 146.9 ^oC, endothermic peak temperature from 150.5 ^oC to 165.9 ^oC, the range of decomposition temperature narrows from 56.2 ^oC to 31.5 ^oC. After modification, sodium bicarbonate shows faster rate of decomposition.

Abstract: The vertical, steady-state breeze vibration of transmission line with dampers attached are studied using FEM analysis. The lines are simulated by cable element, the dampers by mass element and beam element. The parameters of FEM emulation mode such as breeze vibration force, the conductor self-damping and dampers damping are emphasized by the energy equivalent theory. The breeze vibration force induced by vortex is educed by wind power curve, the hysteresis damping and friction damping of conductor and damper are translated into viscous damping. Results of the FEM emulation show the calculation accuracy of natural frequency of dampers, and prove that it can effectively restrain breeze vibration of transmission lines by installing dampers. The method lays foundation for further research on protecting breeze vibration of transmission lines.

Abstract: The inspection of sheet strips post high-speed punching mainly relies on the manual off-line inspection with basic inspection equipment or CCD equipment. Such inspections cannot reflect the real-time conformity of strip machining, and in severe cases, lead to rejects in batches, causing a tremendous waste in production. Now that the application of charge-coupled device (CCD) technology in product inspection is relatively mature, it would be a very good thought to adopt the CCD technology to realize real-time online inspection of conformity of the high-speed punched strips. KeyWords: CCD technology; strip; online automatic inspection; progressive die

Abstract: This paper presented the influence of crystallographic orientation and friction coefficient on the contact stress and fatigue life in the tenon/groove contact region. A rate-dependent crystallographic plastic slip theory was used to calculate the contact stress and fatigue life in [001], [011] and [111] orientations. In the calculation, complex loading conditions and different friction coefficients of 0, 0.2, 0.4, 0.6, 0.8 and 1.0 were taken into account in tenon/groove. Then the relationship between contact stress, fatigue life and friction coefficient was discussed. Simulation results show that: friction coefficient and crystallographic orientation have significant effect on contact stress and fatigue life. Contact stress in [001], [011] and [111] orientation increases with increasing friction coefficient generally. For [001] and [011] orientation, the fatigue life decreases with increasing friction coefficient firstly. When friction coefficient is 0.4, the fatigue life meets its minimum. Then the fatigue life will increase with increasing friction coefficient. For [111] orientation, the change of fatigue life has no obvious trend, and while friction coefficient exceeds 0.6, the life almost constant.

Abstract: This article is based on a certain type of hoist drum, Moreover, we make the stress and mode analysis for the drum, and make preliminary check on it. Then find the position of the weak section, we calculate the force in each stage of hoisting system and draw force-timing load spectrum,we translate it into stress function of weak link. Based on above studies and conclusion, in line with the materials of the drum and Fatigue characteristic parameters and appropriate fatigue lifetime prediction model, we analysis the fatigue performance, in the end get the distribution of the drum’s fatigue life and the life of plane of weakness.

Abstract: Design and analysis of computer experiments (DACE) can solve the optimization design problem for stationary platen effectively. In this paper the method of uniform design is applied to obtain the design of computer experiments which is employed in the optimization design of the stationary platen. 3 factors (11 levels for each factor) are selected. The approximate Kriging model is built on the basis of the FEA results. 10 design points are selected randomly to verify the prediction ability of the Kriging model. The results show that the maximum of the relative error is 2.53% and the minimum is 0.63%. The approximate model built in this paper is practical in the optimization design of the stationary platen. The steps proposed in this paper are also suitable for the optimization design problems with complicated geometry or finite element model.

Abstract: In order to profoundly study on the dynamic characteristic of crankshaft, this thesis applies planar bearing element Combi214 to simulating the bearing supports on both sides of the crankshaft. This study carried out the modal analysis of the crankshaft in multi-step load, and has calculated the low-order vibration mode and frequency of the crankshaft, besides, the top four critical speed and resonant frequency of the crankshaft is obtained via the Campbell chart. The safe range of first critical rotate speed has also been worked out, which is an important reference for the study of structural design and dynamics optimization of crankshaft, and the analysis results and reference in this thesis would provide some valuable basis to improve the four-cylinder engine’s dynamics characteristics.