Advanced Materials Research Vol. 898

Abstract: The solidification microstructure of electron beam scanning is important to product performance. The solidification process of molten pool temperature field and 2D simulation mathematical model of grain growth was established based on heat transfer and the physics of growth process of crystal grains. The heat distribution, thermal physical parameters and influence of thermal radiation on the temperature field was considered during the analysis process. The distribution of temperature field was solved by COMSOL. The process of solidification was simulated by using Monte Carlo method. Using optical microscope to observe the solidified microstructure of bath. The simulation results show that the mathematical model can reasonably describe the grain growth process, the temperature field and the simulation of microstructure morphology.

Abstract: Hexagonal Ni micro/nanoplates were successfully prepared via a facile hydrothermal route using the polyvinylpyrrolidone as structure-directing agent. It has been verified from x-ray powder diffraction and transmission electronic microscopy that as-prepared products with high purity and fine dispersity belong to face-centered cubic microstructure of nickel metal. The magnetic hysteresis loop of the hexagonal Ni micro/nanoplates exhibits the ferromagnetic characteristics, and its coercivity increases by 25 % in comparison with the bulk nickel materials. The possible mechanism of the formation of hexagonal micro/nanoplates was suggested.

Abstract: Epoxy graft acrylate composite latex was synthesized by emulsion polymerization using polymerizable emulsifier. The co-polymer and its structure were characterized by FT-IR and TEM, respectively. The latex particles presented a core-shell structure. The water resistance was investigated and displayed a remarkable result. The corrosion resistance and damping property of the composite latex were evaluated by salt spray cabinet and dynamic mechanical analysis (DMA) respectively. The results indicated that the film has excellent anticorrosive and damping property. These proved that the composite latex had a prominent application potential on the field of functional metal coatings.

Abstract: The corrosion resistance of slag α-Sialon ceramics, prepared via pressure-less sintering and hot-pressing from slag α-Sialon powder, to NaOH and HNO₃ was studied in this work. The result shows that slag α-Sialon ceramics have exellent corrosion resistance to NaOH and good resistance to HNO₃. The corrosion mechanism and corrosion mode of acid and alkali to slag α-Sialon ceramics was investigated by means of scanning electron microscopy (SEM), and the results indicate that the corrosion of acid and alkali to hot-pressing ceramic is the slow surface corrosion, not only on the crystal grains, but also on the grain boundary phase, while the fast pitting is the dominant corrosion mode for pressure-less ceramic. The corrosion of NaOH solution to ceramics mainly occurred the grain boundary phase, while not only the grain boundary phase, but also crystal phase are corroded by HNO₃.

Abstract: Conduction heating overcomes the shortage of the furnace, due to rapid heating and high energy efficiency. The heating experiment of ultra-high strength boron steel (LG1500HS) of a rectangular blank was implemented on the conduction heating system. The variations of the average temperature rising rate, uniform temperature region and energy efficiency were investigated under the non-heating-retaining condition. The results show that the average temperature rising rate, uniform temperature region and energy efficiency are 44.5°C/s, 225 mm and 71.6%, respectively.

Abstract: Web and flange of H-beam are deformed indifferent zone in the rolling process, so non-uniform deformation is easily generated. In order to ensure the uniform elongation of flange and web, usually , the elongation ratio of flange is 3~5% more than that of web. Web wave or crack often appears. Flange wave, crack even tension fracture often appears. Experiment are designed that the elongation ratio of flange and web are changed to ensure the uniform elongation of flange and web. Thus, the rolling quality of H-beam is improved. The recommended rolling rule is provided, which can provide the accordance for actual production.

Abstract: It is difficult to control structural homogenity of H-beam, because of the special section, the metal flowing power is big and the section temperature is uneven. It is expanding strict to the shape of H-beam , dimensional precision and mechanical behaviour. In the process of the metal plastic deform, microstructure transmutation is great effect on the mechanical property. In order to analyse the effect of microstructure on the mechanical property , the tension test is operated and the microstructure effect on the mechanical property is analyzed .

Abstract: Applying the research result of the whole corrugated web H-beam to rail structure, a new kind of rail structure, the corrugated web rail was generated. The special structure rail was successfully rolled in the Research Mill Institute of Yanshan University. This experiment proved that rolling force of corrugated web rail was greater. Based on the software ANSYS/LS-DYNY, the rolling process of corrugated web rail is simulated. Comparing with rolling traditional rail, nip condition, deformation zone, elongation modulus, zone of slippage on the delivery side and on the entry side of rolling corrugated web rail are analyzed, Through the analysis of the character of rolling corrugated web rail, the reason of greater rolling force is found out.

Abstract: According to the production data of a rolling H-beam factory, the FE model of hot continuous rolling process of H-beam is built. With the FEM software of DEFORM-3D, the continuous rolling of H-beam was simulated. On base of simulation result, the metal flow and deformation law are discussed. Because of the flange and web is deformed in the different deformation zone, the metal flow law of flange and web is complex, especially the metal of the conjunction of flange and web. The exchange of metal between the flange and the web of H-beam alters to the different elongation ratio of flange and web. The other factors which influents on the metal flow , are taken into consideration, such as rolling speed and friction coefficient. By adjustment to the rolling parameters, the defect of the H-beam is reduced.

Abstract: Based on the software of Deform-3D , the blooming process of H-beam has been simulated. The effect of different blooming temperature, different initial grain size and different rolling speed on residual stress was analyzed. According to the simulation from result , in the blooming process ,the residual stress of large sized H-Beam is mainly caused by uneven deformation. The big deformation exists in web. The flange deformation is only generated in the rolling surface. This uneven deformation leads to big residual stress in rolling piece. The residual stress of higher blooming temperature is much bigger than that of lower blooming temperature . Enlarging blank grain size has caused residual stress of web reduction, however, the whole residual stress will increase. Increasing the rolling speed of box-pass can significantly reduce the residual stress of R-joint and edges of flange.