Advanced Materials Research Vols. 712-715

Abstract: As a new technology in the field of sheet metal plastic forming, Laser peening forming is a new invention which is based on the laser radiation induced shock waves. In the paper, the orthogonal experimental design is adopted to analyze the interaction of different processing parameters with the sample. Laser bending of thin 1060 pure aluminum sheet with the thickness of 0.25mm was studied by changing the laser energy, scanning velocity, and scanning times to understand the effect of process parameters. The results show that the three parameters have different effects on bending angles, scanning velocity ranks first, followed by scanning times and laser power in terms of their effects on the deformation angle.

Abstract: Combining with practical needs in production, it carried out the numerical simulation analysis of automobile beam stamping forming process based on Dynaform in this paper. According to quality evaluation index of forming parts, it analyzed the effect of variation of blank holder force, the stamping speed, the coefficient of friction and draw bead on stamping quality. It forecast the quality problems happened in forming process, which provides the theoretical basis for design of stamping process and mold.

Abstract: A novel Al-12.7Si-0.7Mg welding wire was successfully produced via DC casting, extrusion, roll die drawing and hole die drawing. An investigation was performed on the microstructure and mechanical properties of the welded joints using the as-produced special filler wire in different solid solution and artificial aging treatment conditions. The results showed that the as-produced Al-12.7Si-0.7Mg welding wire was an ideal special wire of the Al-12.7Si-0.7Mg wrought alloy and the homogeneous welded joints proved to be heat-treatable. Solid solution treatment and artificial aging treatment had significant influence on the microstructure, microhardness and tensile properties of the as-welded joints. A transformation of microstructures from a coarse structure to a fine structure occurred in the welded joints after the heat treatment. The microhardness and the strength of the joints increased remarkably as the solution temperature and aging time increased.

Abstract: Gas bulging with local-stretching preforming is presented to form titanium alloy tubular part with small radius. In ordinary gas bulging process, local thinning occurs at the corners with small radius and produces dangerous position of the component. In the paper, a preforming process so-called local-stretching is applied before gas bulging. Finite element simulation and experiments were carried out to verify the effectiveness of the preforming and gas bulging process for the tubular component of titanium alloy TA15. During the local-stretching preforming, the material near the corner was kept almost rigid, but the material far away from the corner experienced stretching deformation and thickness thinning. Then, during gas bulging, the material near the corner experienced thinning deformation. So, the thickness uniformity of the final component was improved effectively.

Abstract: In order to study the workability and optimize hot forming processing parameters for GH4169 superalloy, the hot deformation behaviors are investigated. The results show that the flow stress strongly depends on the strain rate, deformation temperature and strain. With the increase of strain rates and the decrease of deformation temperature, the flow stress increases. The flow stress exhibits an initial increase with the strain until a peak stress value, showing a obvious work hardening. After the peak stress, increasing strain results in the decrease of stress, indicating a dynamic flow softening. A revised constitutive equation incorporating the effects of temperature, strain rate and work-hardening rate of the material is established by compensation of strain. A good agreement between the measured and predicted results shows that the established model can give an accurate prediction of the flow behavior of GH4169 superalloy.

Abstract: ANSYS/LSDYNA is applied to simulate the sheet forming process and the springback distortion process. The springback result of sheet and stress, strain in process will be obtained. The influencing factor to the springback includes bank holder force, sheet thickness, velocity of punch, and cutting tool radius in process. The springback law can be used to compensate the mould design. Therefore, the structural parameters of the fin forming machine and the process parameters of relative mould device will be optimized. Then the accuracy of offset strip fin will be improved , it will provide a reliable basis for the Fin structure optimization design.

Abstract: With the diversification of manufacture methods, joining the same materials with different states becomes indispensable in practical application. The hybrid welding has broad application prospects. It not only reduces the strict assembled gap before welding, but also improves the joint properties by filling wire during the welding process. 6061 aluminum alloys with different states were welded by YAG-MIG hybrid welding. The characteristics of welded joint, including microstructures, the tensile properties, microhardness and fracture, were investigated. The results show that the microstructures are different significantly in different states. Besides, the grain boundaries of the joint microstructures become unclear after heat treating. The strength and the elongations of welded joints could reach to that of the base metal. The tensile fracture occurs in the fusion zone and near 6061-O alloy. And the fracture presents ductile rupture. Meanwhile, the effect of the small pores in the weld on the joints tensile properties is slight.

Abstract: This article focuses on the realization of a incremental draw forming device for sheet mental. Mold structure is simple. However, the control systems are very complex. The device works under the control of the three-control systems:punch rotation and feeding system, blank holder pressure and return system, blank rotation system. In the incremental draw forming process the punch and blank move synchronously in three axes and a continuous spiral trajectory motion is in use. The final part of dish is obtained through a sequence of localised plastic deformations. This process is very flexible regarding the part of dish geometry and promises a good accuracy. This way, a flexible forming device with simple mold and low costs is realized. On the device using a set of mould can produce different specifications of the parts.So it can be used for rapid prototyping and is suitable for single and small batch production.

Abstract: Thermal Deformation Property and Constitutive Model of AZ80 Magnesium Alloy had been studied with thermal simulation experiment. Dynamic recrystallization for AZ80 magnesium alloy had occurred under different strain rate at 583K(310°C). Dynamic recrystallization had occurred more completely and the grain size was reducing with increasing of strain rate. Dynamic recrystallization had occurred more completely and the grain size was reducing with increasing of strain rate. According the Arrhenius equation, a kind of constitutive equation of AZ80 Magnesium alloy which considered the strain had been put forward, and the relative errors between calculation results by the stress-strain model and experiment results are less than 10.5%.

Abstract: The deep drawing of SiC/2024Al composites using pulse current heating were designed and established in this works. The whole process system mainly include pulse current heating system, electrode lifting system, temperature control system and deep drawing forming system. In addition, the feasibility of thermal deep drawing using pulse current heating was experimentally investigated and the optimal process parameters were explored to ensure defect-free products. The temperature of specimen is up to around 673K at a rate of 13.5K/s under the current density of 21.7A/mm². The stainless steel inserts make temperature difference reducing by 73.3%. Moreover, the workpiece was successfully deep drawn and exhibited good surface quality. The dimensional accuracy achieved within ±0.2mm.