摘要：The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element *** range of extrusion speed was determined by considering the maximum extrusion load and production *** taking the optimal solution temperature of the secondary phase as the target temperature,the extrusion speed–stroke curve for realizing the isothermal extrusion of the aluminium profile was *** show that in the traditional constant extrusion speed process,the average temperature of the cross-section of the aluminium profile at the die exit rapidly increases and then slowly rises with the increase in ram *** the extrusion speed increases,the temperature difference at the die exit of the profile along the extrusion direction *** exit temperature difference between the front and back ends of the extrudate along the extrusion direction obtained by adopting isothermal extrusion is about 6.9℃.Furthermore,the heat generated by plastic deformation and friction during extrusion is balanced with the heat transfer from the workpiece to the container,porthole die and external environment.

摘要：The interfacial heat transfer coefficient between hot profile surface and cooling water was determined by using inverse heat conduction model combined with end quenching experiment. Then, a Deform-3 D thermo-mechanical coupling model for simulating the on-line water quenching of extruded profile with unequal and large thicknesses was developed. The temperature field, residual stress field and distortion of profile during quenching were investigated systematically. The results show that heat transfer coefficient increases as water flow rate increases. The peak heat transfer coefficient with higher water flow rates appears at lower interface temperatures. The temperature distribution across the cross-section of profile during quenching is severe nonuniform and the maximum temperature difference is 300 ℃ at quenching time of 3.49 s. The temperature difference through the thickness of different parts of profile first increases sharply to a maximum value, and then gradually decreases. The temperature gradient increases obviously with the increase of thickness of parts. After quenching, there exist large residual stresses on the inner side of joints of profile and the two ends of part with thickness of 10 mm. The profile presents a twisting-type distortion across the cross-section under non-uniform cooling and the maximum twisting angle during quenching is 2.78°.

摘要：6061 aluminum alloy T-joints were welded by double-pulsed MIG welding process. Then, the post-weld heat treatment was performed on the welded T-joints. The weld microstructure under different aging temperature and time was investigated by transmission electron microscopy and scanning electron microscopy. The mechanical properties were examined by hardness test and tensile test. The results showed that the micro-hardness was sensitive to heat treatment temperature and time. Increasing temperature was beneficial to the shortening of peak aging time. There were a large number of dislocations and few precipitates in the welded joints. With the increase of post-weld heat treatment temperature and time, the density of dislocation decreased. Meanwhile, the strengthening phase precipitated and grew up gradually. When the post-weld heat treatment temperature increased up to 200℃, large Q' phases were observed. And they were responsible for the peak value of the micro-hardness in the welded joints.

摘要：To solve the defects of bottom concave appearing in the extrusion experiments of complex hollow aluminium profiles,a 3D finite element model for simulating steady-state porthole die extrusion process was established based on HyperXtrude software using Arbitrary Lagrangian–Eulerian(ALE)*** velocity distribution on the cross-section of the extrudate at the die exit and pressure distribution at different heights in the welding chamber were quantitatively *** obtain an uniformity of metal flow velocity at the die exit,the porthole die structure was optimized by adding baffle *** optimization,maximum displacement in the Y direction at the bottom of profile decreases from 1.1 to 0.15 mm,and the concave defects are remarkably *** research method provides an effective guidance for improving extrusion defects and optimizing the metal flow of complex hollow aluminium profiles during porthole die extrusion.

摘要：The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and *** grain morphology was observed by means of electron backscatter diffraction(EBSD)*** results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain *** contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain *** microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix *** grain size in the welding zone was smaller than that in the matrix zone due to lower DRX *** decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.

摘要：3D elastic-plastic FE model for simulating the force controlled stretch-bending process of double-cavity aluminum profile was established using hybrid explicit−implicit solvent *** the computational accuracy and efficiency,the optimal choices of numerical parameters and algorithms in FE modelling were *** formation mechanisms of cross-section distortion and springback were *** effects of pre-stretching,post-stretching,friction,and the addition of internal fillers on forming quality were *** results show that the stress state of profile in stretch-bending is uniaxial with only a circumferential *** stress distribution along the length direction of profile is non-uniform and the maximum tensile stress is located at a certain distance away from the center of *** aluminum profile is gradually attached to bending die,the distribution characteristic of cross-section distortion along the length direction of profile changes from V-shape to *** unloading the forming tools,cross-section distortion decreases obviously due to the stress relaxation,with a maximum distortion difference of 13%before and after *** pre-stretching and post-stretching forces increase,cross-section distortion increases gradually,while springback first decreases and then remains *** increasing friction between bending die and profile,cross-section distortion slightly decreases,while springback ***-section distortion decreases by 83%with adding PVC fillers into the cavities of profile,while springback increases by 192.2%.

摘要：Bending deformation behaviors of solution treated(ST),natural aged(NA)and T6tempered6063aluminum alloy sheetswere studied by three-point bending *** changes of bending force,interior angle,bending radius and sheet thickness in thefillet region were analyzed by experimental measurements and numerical *** results showed that the bendingcharacteristics were strongly dependent on the heat treatment *** T6alloy sheets were bent more sharply and localplastic deformation occurred severely in the fillet ***,the ST and NA alloy sheets exhibited relatively uniform bendingdeformation and large bending *** bending force of T6alloy was the highest,followed by the NA alloy and that of the STalloy was *** unloading,as compared with the ST and NA alloys,the springback of T6alloys was markedly *** time showed a positive sensitivity on the springback and non-uniform bending *** bending characteristics areattributed to the combined effects of yield strength,yield ratio and coefficient of neutral layer.

摘要：目的设计、合成含有二氢吡唑杂环结构的黄酮类衍生物,并初步探讨其体外抗氧化活性。方法以邻苯二酚为起始原料合成先导化合物7-羟基黄酮,与1,2-二溴乙烷反应得到7-溴乙氧基黄酮再经与含有邻羟基苯取代的二氢吡唑类化合物缩合得到6个含有二氢吡唑杂环结构的黄酮衍生物。目标化合物的结构通过IR、~1H-NMR、^(13)C-NMR、ESI-MS和元素分析进行确证。测定了目标化合物清除超氧自由基(O2-·)、羟自由基(·OH)、亚硝基自由基(NO_2·)和2,2-二苯基-1-苦味酰基自由基(DPPH·)的活性及总还原能力。结果在0.5 mg·mL^(-1)时,多数目标化合物具有抗氧化活性,但均弱于对照维生素C的抗氧化作用。结论 7-(1-苯基-3-甲基-4,5-二氢吡唑-5-苯基)-氧乙氧基黄酮(化合物2a)对4种自由基的清除作用及其总还原能力均较强,可以进一步进行体内抗氧化活性研究。

摘要：为探究施肥种类对小黑麦(Triticosecale)与饲用豌豆(Pisum sativa)和箭筈豌豆(Vicia sativa)混播草地生产性能,营养品质和经济效益的影响。本试验采用裂区设计,主区为施肥种类(不施肥、化学肥料、有机肥和菌肥),副区为混播组合(M_(1):50%小黑麦×50%‘加拿大’饲用豌豆,M_(2):50%小黑麦×50%‘西牧333’箭筈豌豆,M_(3):50%小黑麦×50%‘绿箭1号’箭筈豌豆)。结果表明:从施肥种类来看,与化肥相比,有机肥和菌肥使混播草地的干草产量分别下降了7.62%和16.40%,但粗蛋白含量分别提高了0.68%和1.29%,相对饲喂价值分别提高了7.46%和5.38%。从混播组合来看,50%小黑麦和50%‘西牧333’箭筈豌豆的混播效果较好,纯收益高,适合在甘南高寒牧区推广种植。总体来看,与化肥相比,单独施用有机肥或菌肥使混播草地的纯收益显著降低。在氮用量相近时,施用有机肥使施肥成本增加6171 CNY·hm^(-2)。因此,甘南州在饲草生产中不宜采用有机肥或菌肥完全替代化肥的方案,应考虑部分替代化肥的策略,以保障作物高产,增加农牧民收入。

摘要：To improve billet quality and the trackability and stability of secondary cooling water during continuous casting, the superheat is introduced into the water distribution for secondary cooling to design the relevant control system, based on the water distribution model, superheat and fuzzy self-adaptive PID （process identity） . A spray cooling system is set up for simulation test in laboratory to test the step signal from the conventional, integral sepa rated and fuzzy self-adaptive PID controllers and the simulation casting. And the on-site test is done in some steel plant. The test results show that the fuzzy self-adaptive PID controller＇s performance is better than that of the other two controllers, which provides a basis for further study and application.