Advanced Materials Research Vols. 1004-1005

Abstract: Although still having certain limitations, the numerical simulation technology has been increasingly applied to aid in optimizing the aluminum extrusion process and die design. In the present research, numerical simulations of the profiles extrusion process were performed, using the Finite Volume Method (FVM) and Finite Element Method (FEM) to make use of the individual merits of the Euler approach and Lagrange approach, respectively. The application of the simulation technology to produce large, complex profiles has, however, been quite limited. In order to solve the limited, numerical simulation of aluminum profiles with large and complicated cross-section in extrusion process was achieved using Arbitrary Lagrangian-Eulerian (ALE) approach, and non-uniform velocities at the die exit, leading to extrudate distortions, were predicted. Extrusion experiments proved that the die with the optimized design could circumvent the distortion problem. The numerical simulation technology can indeed be effectively used to reduce the number of die trials and offer the potential to realize zero die trial.

Abstract: Thermoforming is a typical method of ultra high strength steel plate’s forming for the automotive industry, where the 22MnB5 sheet is widely used. This article discusses how to simulate the thermoforming process of the 22MnB5 by using the thermal coupling software which is called Pam-stamp 2011. After that, we got the distribution of temperature、thickness and thinning rate of thermoforming parts.

Abstract: Firstly, the online detecting and controlling models of the strip steel mechanical properties in skin-pass process are proposed in this paper. The models are used to overcome the shortage of the conventional monitoring methods, and to reduce the fluctuations of the mechanical properties of the strip. The new online detecting and controlling models can real-time forecast the mechanical properties of the running strip from the online monitoring devices. The bias control between the forecasting and the target values of the mechanical properties can be corrected by adjusting the strip elongation . As a result , the fluctuations of the mechanical properties of the strip are reduced ,and move over,it is helpful to prevent the higher yield strength and lower tensile strength, and to maintain good formability strip.The experiments are done and verify the validity of the approach.

Abstract: The research is focused on relationship between structural parameters and stress distribution of the horizontal filtering tank`s filtering plate used in chemical equipment production, innovative made use of elliptic filtering plate to improve the strength and structural instability of the horizontal filtering tank .Though the collaborative optimization design features of Pro / E software and Ansys Workbench software to analyze horizontal filtering tank. The Spearman, Pearson product-moment correlation coefficient was informed that the main factor is elliptic filtering plate. Studies have shown that, with the length of elliptic filtering plate`s minor axis increases, the maximum stress on the horizontal filtering tank, the total displacement of deformation and the effective stress are decreased, but with increasing the length of the elliptic filtering plate`s minor axis, the effective filtration area that plate can use becomes smaller. According to the optimization results, premised on the design requirements, the length of elliptic filtering plate`s minor axis should take 1257mm, now the structure of horizontal filtering tank is better.

Abstract: A novel method for simultaneous determination of ruthenium and zinc in catalysts for hydrogenation of benzene to cyclohexene was established by inductively coupled plasma optical emission spectrometry after sample digestion by high temperature fusion with Na₂O₂. Such experiment conditions were investigated as the influence of sample digestion methods, fusion time, fusion temperature, the dosage of Na₂O₂ and interfering ions on the determination. Under the optimized conditions, the limits of detection (LODs) of Ru and Zn for tested solutions were 11 and 13 ng mL^-1, respectively. The relative standard deviations (RSDs) for Ru and Zn were 2.01 and 2.35 % (C_{Ru, Zn} = 1 mg L^-1, n = 7), respectively. The linear ranges of calibration graphs for Ru and Zn were 0.05 ~ 100.00 mg L^-1 and 0.04 ~ 50.00 mg L^-1, respectively. The proposed method was applied to determine catalyst samples with good recoveries and satisfactory results.

Abstract: In this paper, we investigate the stress distribution on a two phase problem in micro-extrusion. Molten polymer is compressed from a vessel and the extruded fluid is being solidified through the heat exchange with the solid polymer and the ambient environment resulting in a two phase/moving boundary problem. The temperature profile of such problem has analytically been determined and the present author, Chan further investigates the fluid flow of the molten polymer embedded inside the condensed outer-shell. In this paper, we investigate the stress distribution induced by the fluid flow, which is driven by the incoming fluid and the moving boundary. We find that when x’>>H (see Fig. 1), shear stress dominates whereas the principal stress dominates when x’<<H. When x’ approximates H, both the shear and principal stresses coexist.

Abstract: A hot rolling method to produce Mg-Gd-Y-Nd-Zr alloy bars through oval-vertical elliptical-round pass system is put forward. The mechanical model of Mg-Gd-Y-Nd-Zr alloy has been established. Using Deform-3D software, the rolling process of Mg-Gd-Y-Nd-Zr alloy bar is simulated at rolling temperature 450°C, rolling speed 0.4m/s. And equivalent stress distribution and load variation has been obtained. It provides a theoretical basis for the hot rolling bars of magnesium alloy. The experiment verifies that the hot rolling process is feasible. The organizational structure is analyzed with metallographic microscope, and the results show that dynamic recrystallization is occurred, the grain size is obviously refined, and the mechanical property of the material is improved in hot rolling process.

Abstract: In order to study the basic rule of diamond wire saw slicing SiCp-Al composites, the theoretical analysis and experiments were carried out. The influences of diamond wire saw slicing speed and workpiece feed speed on surface quality and machining efficiency were discussed. The analysis results show that the machined surface gets smoother when diamond wire saw slicing speed changes from 2m/s to 3.5m/s, but gets rougher when diamond wire saw slicing speed changes from 3.5m/s to 4m/s. And the surface gets rougher when workpiece feed speed changes from 0.5m/s to 1m/s.The machining efficiency gets higher when diamond wire saw slicing speed and workpiece feed speed increase. These results provide guidance for selecting reasonable parameters in future research.

Abstract: Cold expansion was employed on 7050-T7451 aluminum. Residual stresses were measured, fatigue tests were carried out for joints with different expansion, and the fracture surfaces of specimens were observed by scanning electron microscope (SEM). The results show that residual compressive stresses generate by cold expansion process. The maximum values of radial residual compressive stresses locate the middle of the inner wall of the hole and residual compressive stresses extend radially up to one diameter from the edge of the hole. Axial residual compressive stresses distribute near the exit. The fatigue lives N₅₀ and N_95,95 for specimen with strengthened hole with 5% expansion are respectively 3.54 and 3.68 times compared with non-strengthened hole. Fatigue fracture morphology shows the characteristics of mixed transgranular fracture and the propagation speed of the crack along horizontal direction is larger than vertical direction.

Abstract: The paper studied the tribological performances of n-Na₂B₄O₇/ion nitrocarburized duplex layer at different temperatures. It is found that the n-Na₂B₄O₇/ion nitrocarburized duplex layer has more excellent friction reduction and wear resistance performances than the intermediate frequency quenched surface under CD15W-40 oil lubricating at different temperatures, especially at the higher temperature 100°C, the friction factor and volume loss of the duplex layer is 63% and 96% less than that of the intermediate frequency quenched surface respectively, which indicates that n-Na₂B₄O₇/ion nitrocarburized duplex layer can play more excellent friction reduction, wear resistance and scuffing resistance performances at the relative higher temperature. This because that the chemical reaction films including oxide, BN and so on formed on the friction surface play the solid lubrication function, and the n-Na₂B₄O₇ particles on the friction surface play the "Micron nanobearing" function.