Effect of rolling temperature on microstructure and mechanical properties of 6063 Al alloy

Aluminium alloy (6063) was severely rolled upto 92% thickness reduction at liquid nitrogen temperature and room temperature to study the effect of rolling temperature on its mechanical properties and microstructural characteristics by using tensile tests and SEM/electron back scattered diffraction (EBSD), transmission electron microscope (TEM), DSC, X-ray diffraction (XRD) as compared to room temperature rolled (RTR) material with the same deformation strain. An improved strength (257 MPa) of cryorolled 6063 Al alloy was observed as compared to the room temperature rolled alloy (232 MPa). The improved strength of cryorolled alloy is due to the accumulation of higher dislocation density than the room temperature rolled material. The tensile properties of cryorolled alloy and the alloy subjected to different annealing treatments were measured. The cryorolled alloy subjected to annealing treatment at 300 °C for 5 min exhibits an ultrafine-grained (UFG) microstructure with improved tensile strength and ductility.     

唐河水电站堆石坝基础处理与堆石料填筑施工

唐河水电站的坝型是混凝土面板堆石坝，坝高26．9m，坝顶长度280．5m。文中叙述了坝基处理、坝体碾压试验及筑坝的方法。     

镍-钛爆炸复合板的轧制

本文叙述了镍-钛爆炸复合板热轧和冷轧的工艺、组织和性能。     

轧钢燃油加热炉燃烧技术的探讨与实践

以提高轧钢加热炉燃油燃烧技术为题，详细地阐述了提高重油燃烧前的质量与温度，改进与完善供油设备和燃烧设施在节能中的作用，着重介绍了新型重油加热系统在轧钢炉上的应用与效果。     

变质处理高碳高速钢导板的研究

导板是线材轧机的关键备件，要求有优良的耐磨性，抗断裂性，抗粘钢性和热冲击抗力，常用高镍镍钢导板和高铬铸铁导板满足不了上述要求，使用寿命短，更换频繁，降低了轧机作业率，增大了工人劳动强度，高速钢具有硬度高，红硬性好和耐磨性好等特点，但铸造高速钢脆性大，通过调整高速钢成分和采用RE－Mg-Ti复合变质处理，可改变共晶碳化物的形态和分布，使高速钢冲击韧性大幅度提高，变质处理高速钢导板使用中不粘钢，不断裂，耐磨性明显优于普通导板。     

基于遗传算法的BP神经网络滚动轴承故障诊断

针对滚动轴承的故障诊断问题,提出了一种基于遗传算法的BP神经网络滚动轴承故障诊断方法。以BP神经网络的误差为目标函数,利用遗传算法进行BP神经网络的权值和阈值优化,并用优化后的BP神经网络进行故障诊断。通过MATLAB仿真,结果表明遗传算法优化的BP神经网络相比传统的BP神经网络具有更好的诊断效率和准确度。     

三辊斜轧机轧制外螺纹管件工艺分析

对采用三辊斜轧机轧制外螺纹管件的工艺过程进行了分析,特别分析了压下量、螺纹升角、送进角等工艺参数对产品质量的影响。     

Binding property of Al/Mg/Al thin plates fabricated by one-pass hot rolling with different reduction ratios,temperatures and annealing treatments

In this study, Al-Mg-Al trilaminated thin plates were fabricated by one-pass hot rolling to improve the processing capacity and bonding strength of magnesium alloy plates. The effects of processing parameters were investigated. The results show that the optimal bonding strength is up to 20 MPa with a reduction ratio of 40 % and rolling temperature of 400 ℃, superior than that in other one-pass rolling studies with regard to thin laminated plates. In addition, a favorable property is achieved with the annealing temperature of 250-300 ℃ or annealing time of 1.5 h. When the annealing temperature exceeds300 ℃ or annealing time exceeds 1.5 h, respectively, the bonding strength of Al/Mg/Al plate decreases. The scanning electron microscopy(SEM) and energy-dispersive spectroscopy(EDS) analyses suggest that the appearance of thin diffusion layers between A1 and Mg interfaces is helpful to improve the bonding strength, while the presence of thick diffusion layer would reduce the bonding strength greatly.     

摩擦对高温合金复杂截面圆环多道次滚压成形不均匀变形作用

在高温合金复杂截面薄壁圆环多道次滚压成形过程中,板料要经历多场多因素偶合作用下复杂的不均匀塑性变形和组织演化历程,特别是不均匀塑性变形通常是导致薄壁件成形起皱、椭圆和开裂等缺陷产生的主要因素。摩擦是描述环件与辊轮接触作用的主要参数,很大程度上决定着该环件多道次滚压成形过程中塑性变形的不均匀性,严重的影响着其滚压成形质量。为此,本文以有限元仿真为主并结合实验和理论方法,对高温合金GH4169薄壁w形圆环多道次滚压成形进行了系统的分析;进而提出了不均匀变形度的表征方法,研究获得了摩擦对高温合金复杂截面薄壁圆环多道次滚压成形不均匀变形的影响规律。结果表明：随着滚压成形的进行等效应力极值逐渐增大,且从动辊进给时环件弯曲部分材料变形量较大;随着驱动、从动辊与环件之间摩擦系数的增加,不均匀变形程度先减小,后逐渐增大;导向辊与环件之间的摩擦对不均匀变形度的影响不大。     

Effect of deformation mode,dynamic recrystallization and twinning on rolling texture evolution of AZ31 magnesium alloys

In order to obtain quantitative relationship between (0002) texture intensity and hot rolling conditions, conventional rolling experiments on AZ31 magnesium alloys were performed with 20%–40% reductions and temperatures within the range of 300–500 °C. Shear strain and equivalent strain distributions along the thickness of the rolled sheets were calculated experimentally using embedded pin in a rolling sheet. Rolling microstructures and textures in the sheet surface and center layers of the AZ31 alloys were measured by optical microscopy (OM), X-ray diffractometry (XRD) and electron back scatter diffraction (EBSD). Effects of the rolling strain, dynamic recrystallization (DRX) and twinning on the texture evolution of the AZ31 alloys were investigated quantitatively. It is found that the highest (0002) basal texture intensities are obtained at a starting rolling temperature of 400 °C under the same strain. Strain–temperature dependency of the (0002) texture intensity of the AZ31 alloy is derived.