Advanced Materials Research Vols. 774-776

Abstract: The spinning temperature is one of key factors affected the uneven deformation during the hot power backward spinning for brittle material tubes, such as cast 7075 aluminium alloy tube. To analyze the evolution regularity of temperature filed in the spinning process, a 3D thermo-mechanical FE model of the process is developed under ABAQUS/Explicit environment. Then, the evolution of temperature filed during the process is analyzed based on the FE model. The results show that: The contact areas temperatures between lock ring, spinning rollers and tube decrease sharply during the initial spinning stage. The high temperature region is transferred from unformed zone of the tube to the contact area between spinning roller and tube. In the spinning zone, the temperature of internal surface of the tube is apparently higher than that of outer face.

Abstract: This paper describes the development of an off-line feed rate scheduling technique based on a mechanistic cutting force model. The proposed technique was developed for an end milling operation. The surface area of the workpiece was divided into a number of segments, and the resultant cutting force at each discrete segment was determined using One Path Analysis software. The calculated resultant cutting force was applied to the feed rate scheduling. Experimental results clearly showed that the implementation of feed rate scheduling reduces machining time considerably and that as the number of segments increases, the effectiveness of the feed rate scheduling increases.

Abstract: U71Mn is the main steel grade for high-speed railway rails. In the production of U71Mn rail, its decarburization depth is the deepest, and the qualified percentage is lower than 60% for the requirement of less than 0.3mm of decarburization depth. On the basis of current heating furnace, the influence of different heating processes on the decarburization depth of U71Mn rail was studied, and the result shows that just optimization of heat process can not decrease greatly the decarburization depth. Therefore the high temperature anti-oxidation coating protection technology was carried out in the process of heating of U71Mn rail. Under the condition of protection heating and optimization of heating process, the decarburization depth of U71Mn rail decreases significantly, and the qualified rate reaches to more than 95% for the depth of less than 0.30mm, and 100% for the depth of less than 0.50mm.

Abstract: In this paper, through analysed the strain and stress of sheet inner-concave flanging and observed result of finite element simulation, the law of strain distribution in outer edge area of deformation.By simplified the distributed regularity, a method to predict the shape distortion of outer edge area of deformation was obtained, the calculation results and the finite element simulation results are nearly equal to each other.

Abstract: In the spray forming process, the atomizing quality is not very good under the low pressure. This article attempts to improve the quality of atomization through heating the gas. A mathematical model is built and calculated according to the existing knowledge, and then the influence of airflow temperature in the spray forming is theoretical calculated and analyzed. The experimental results show that the average grain size is 54μm when the gas is not heated; the average grain size is 39 μm which decreases by 27.7% than airflow unheated when the gas is heated to 150 °C. The calculation results show that when the gas is not heated, the first time atomization grain size is 201 μm, the second time atomization grain size is 15 μm, the total atomization time is 92 μs. And the velocity of atomization droplets is 80 m/s; when the airflow temperature is 150°C, the above results are 131 μm, 10 μm, 76 μs and 127 m/s respectively, the atomization quality has a certain improvement compared to the unheated condition. At the same time, the grain shape becomes more round as the temperature of airflow increases, and the holes between the grains also become smaller.

Abstract: The key to recycling of old asphalt mixture is waste asphalt recycle, three regenerants were used as modifiers for old asphalt mortars, three major indexes and rotary viscosity after mixing it with waste asphalt recycle and measured, and simulating a transfer of the old asphalt mortars, then which evaluate on compatibility of the old asphalt and regenerant, to provide reference basis for the choice of regenerant.

Abstract: With hot forming parts of ultra-high strength steel (UHSS) widely used, requirements on matching the mechanical properties of parts with the performance on active service are attracting attention. Research shows that the preheat temperature of the molds set to 400°C or above can effectively reduce the hardness of the sheet and get a better region. The width of the air gap between tools is important influencing factor. Too large air gap will increase the difficulty of controlling the region of variable intensity and the position of ultimate strength.

Abstract: Supersonic Particles Bombarding (SSPB) can introduce severe plastic deformation on the surface of metallic materials, and nanostructured surface layer can be fabricated on the materails. So SSPB is a promosing technology which can be applied in industry. Main parameters of SSPB were optimized by orthogonal design, and their effect on the weight loss of the SSPB treated sample was analysed. Optimized parameters were obtained after the orthogonal experiments.

Abstract: A novel quantum multi-objective evolutionary algorithm is proposed that combine the quantum computing with multi-objective evolutionary algorithm, and the quantum chromosomes is updated with the chaos in order to enhance the optimization capability of the quantum population. To verify the performance of the proposed algorithm, the functions ZDT1 and ZDT2 are optimized by the proposed algorithm and NSGA-II. The results show that the quantum chaos multi-objective evolutionary algorithm has the more powerful capability. The new proposed algorithm is applied to the load distribution optimization of tandem cold mill, and the two-objective function modal is built based on the minimum energy consumption and rolling force equilibrium. Optimizing the modal with the new algorithm, the empirical data and method of weighting, the result of quantum chaos multi-objective evolutionary algorithm is more reasonable. Therefore, the quantum chaos multi-objective evolutionary algorithm is a practicable intelligent optimization method for the load distribution optimization of tandem cold mill.

Abstract: he macro fracture of broken drill pipe friction welded joints and characterizations of microstructure were performed by SEM and XRD, and tested its hardness. The results suggested that the large area of “gray leaf spot” (composition: Fe₃O₄) which is on friction welded joints is the main reason causing the drill pipe brittle fracture. In order to avoid excessive “gray leaf spot” defects during the friction welding, put forward practical recommendations.