Advanced Materials Research Vols. 557-559

Abstract: According to the structure of the crank arm, the conformal mapping method was adopted to transform the elliptical section map of it to the round. Then by the slab method an analytical model for final upsetting force of the crank arm was established, which is a derivation based on assumptions of axisymmetric plastic forming status. Finally, a simulation was implemented in case of the second crank of crankshaft 6G32. Accordance to it the accuracy of the analytical model was examined. Further more the causes of the data deviation from the model and the simulation were analyzed in this thesis.

Abstract: The cold-welded surfacing layers have been prepared with SKD61 welding wire by high-energy pulsed cold-welding technology on 18Cr2Ni4WA steel. The microstructure of cold-welded surfacing layers was observed by Scanning Electron Microscope(SEM)and the bonding Strength and mircohardness were tested as well. The results showed that the microstructure of cold-welded surfacing layer is mainly composed of acicular martensite ; the matrix structure of composition is granular bainite;The mean cohesive strength of cold-welded surfacing layer is 826MPa;and its mean microhardness(393.5HV)is obviously higher than that of substrate, which can increase the anti-wear property of material.

Abstract: Microstructure of electromagnetic pulse tungstic electrode argon arc welding (EMP-TIG) welded Mg/Al dissimilar metal joint is studyed using optical microscope, scanning electron microscope, and X-ray diffraction. The results indicate that gas tungsten arc welding can provide Mg/Al joint with excellent microstructure and performance. The welding region is composed of Mg₃Al₂ phase, α(Mg), β(Li), and MgAl. The weld zone and the Al alloy base materials are well combined. There are massive MgAl phase dendrites in the weld area, which cause the significantly increase of hardness at weld zone. Near the Mg-8Li alloy base metal side of the weld zone, there exists a layer of 100~ 200μm equiaxed region. About 1μm Mg₃Al₂ reaction layer is distributed between Mg-8Li alloy base metal and the equiaxed grains. This reaction layer and the Mg-8Li alloy base metal, as well as the weld zone of equiaxed grains, have a good combination.

Abstract: High-speed metal cutting processes can cause extremely rapid heating of the work material. Temperature on the machined surface is critical for surface integrity and the performance of a precision component. However, the temperature of a machined surface is challenging for in-situ measurement.So, the finite element(FE) method used to analyze the unique nonlinear problems during cutting process. In terms of heat-force coupled problem, the thermo-plastic FE model was proposed to predict the cutting temperature distribution using separated iterative method. Several key techniques such as material constitutive relations, tool-chip interface friction and separation and damage fracture criterion were modeled. Based on the updated Lagrange and arbitrary Lagrangian-Eulerian (ALE) method, the temperature field in high speed orthogonal cutting of carbon steel AISI-1045 were simulated. The simulated results showed good agreement with the experimental results, which validated the precision of the process simulation method. Meanwhile, the influence of the process variables such as cutting speed, cutting depth, etc. on the temperature distribution was investigated.

Abstract: A calculation method for die matching of drawing round tube named arithmetic decrease method is introduced in this paper. The cold-drawing procedure of a specific aluminum round tube was investigated as a case study. FE simulation in DEFORM-2D was taken as a tool of check and optimization, which helps to improve the application of arithmetic decrease method.

Abstract: Abstract: The computational fluid dynamics software POLYFLOW was used to simulate the inflation stage in extrusion blow molding of an HDPE oil drum and calculate the velocity distribution of parsion, the thickness distribution and contact time after inflation. The results show that, the thickness decreases as the blowing pressure increases. The thickness at the bottom and corners of the blown drum is thinner than that at others. The velocity increases as the blowing pressure increases after pinch-off. The parison contacts with the mould earlier as the blowing pressure increases. In the region of the handle, the contact time is the shortest.

Abstract: EVA was tried to improve the compatibility between wood flour and plastics substrate as a new kind of coupling agent. Infrared diffuse reflectance spectroscopy was applied to examine the changes in surface groups. The influence of the EVA content on the mechanical properties of WPCs was investigated and the morphologies of fractured surfaces were examined using a scanning electron microscope (SEM). Infrared diffuse reflectance spectroscopy shows that the EVA reduced the polarity of the wood flour. When the content of EVA is increased the mechanical properties of WPCs also increased. The SEM showed that EVA can help improve the interface compatibility between the fiber and plastic by aiding in the bonding of more plastic to the wood fiber. The comprehensive performance of the WPCs reached its maximum potential when the EVA level was at 15%.

Abstract: Color difference on surface of aluminum alloy stripes when lubricated with oil-water mixtures in cold continuous rolling process was researched. The surface profile, 3D and micro morphology were observed by surface surface profiler, laser scanning confocal microscopeand scanning electron microscope. The chemical composition of aluminum surface was analyzed by X-ray energy dispersive spectrometer, and then the formation mechanism of color difference was studied. The results indicate that lubricated with oil-water mixture, oil and water can't mix sufficiently and lubrication failure was found in deformation zone because of lubrication oil shortage. Working roller and fresh surface of stripes contacted directly and leaded to adhesive, so lots of irregular shaped micro-cracks were found after rolling, the residual composition of oil-water mixture adsorbed in the micro-cracks and not easy to be cleaned up, so the organic matter of residue composition carbonized and manifested as color difference in the visible. The fringes of color difference are distributed approximately along the rolling direction and the average roughness was very nearly the same between different kinds of fringes.

Abstract: Two kinds of C-Si-Mn-Cr-Mo-Nb tested steels with different C content were disigned, and controlled rolling and controlled cooling experiment of tested steels have been carried out in lab to analyze the effect of C on microstructure and mechanical property of high strength hot rolled dual phase steel. It is shown that two kinds of tested steels obtained ferrite and martensite microstructure under controlled rolling and step cooling process. With the increase of C content from 0.032wt% to 0.064wt%, ferrite grain size refines from 9.8μm to 5.0μm, width of martensite colony reduces from 10μm to 5.8μm, and martensite volume fraction increases from 11% to 25%. Yielding strength of high C tested steel is higher than that of low C steel by 55MPa, and amplification of tensile strength is about 155MPa. Elongation ratio decreases about 6.4%. Increasing of yielding strength is determined by strengthening of ferrite grain refining. The amplification of tensile strength is effect by volume fraction and refining of strengthening phase.

Abstract: In this paper, the machining properties of Xylia spp, compared with Castanopsis hystrix, were tested. Their properties were conducted according to the criteria ASTM D1666-87 and the test on crosscutting is referred to the method established by New Zealand Forest Research Institute. The results show as follow: the machining properties of Xylia spp and Castanopsis hystrix in the planning, sanding, boring, shaping and crosscutting show excellent, but the mortising properties was a bit poor. The properties of Xylia spp were in an all-round way better than Castanopsis hystrix. In the machining performance comprehensive evaluation system for full marks 50 points, its comprehensive marks were separately 45.5 points and 44.4 points.