Development of low thermal expansion superalloy

Alloy 903 and Alloy 909 are well-known Fe-Co-Ni-Al-Ti-Nb alloys with controlled low thermal expan-sion, but they have some properties that can be improved. To improve stress-accelerated grain boundary oxidation embrittlement of Alloy 903 and instability of theγ phase of alloy 909, two new alloys with good stress-rupture ductility, high creep-rupture strength, high tensile strength at high temperature, and good controlled thermal expansion were developed. These property improvements were accomplished by the combination of optimizing the Fe-Co-Ni ratio of the matrix and stabilizing theγ phase with the addition of aluminum.     

考虑材料剪胀性的球形空腔扩张问题的弹塑性分析

在考虑材料剪胀性和塑性区弹性变形的情况下 ,研究了塑性区中弹、塑性变形情况以及对应力场、位移场的影响。研究表明剪胀角 ψ和内摩擦角对弹塑性交界处半径R有显著影响 ;给出了塑性区中平均体积应变及弹、塑性变形体积的计算公式和剪胀角的测试方法。通过算例研究发现 ,弹塑性交界处半径R随着剪胀角 ψ的增大而逐渐减小 ,塑性区平均体积应变却随着剪胀角 ψ的增大而增大。研究表明塑性区中弹性变形部分忽略是不合理的     

小型球铁件的收缩特点及其补缩工艺

根据国内外有关研究结果，阐述了球墨铸铁件冷却凝固过程中的体积变化规律，建立了球墨铸铁的收缩和膨胀模型，用以分析球墨铸铁小件的缩孔缩松形成机理。以轮毂铸件为例提出了防止缩孔缩松缺陷的工艺措施。     

Crystal structures and thermal expansion properties of Y2-xErxMo4O15 （x=0.0-2.0） solid solutions

A new series of rare earth compounds,Y2-xErxMo4O15 （x=0.0-2.0）,were synthesized and their structures were determined by powder X-ray diffraction （XRD）. Rietveld analysis of XRD patterns reveals that the compounds of this series crystallize in monoclinic system with space group P21/c. The lattice parameters a,b,c,β and the unit cell volume V de-crease linearly with increasing Er content. The thermal expansion properties of these compounds were studied under high-temperature XRD. Positive thermal expansions of compounds Y2-xErxMo4O15 are found to be anisotropic along the three crystallographic directions where a and c axes expand while b axis contracts in the whole temperature range. By analysis of data,the expansion of weak band Mo2-O14 with rising temperature should be responsible for positive thermal expansion.     

延长尾矿库服务年限的途径

尾矿库是矿山企业中重要的生产和安全环保设施,由于盲目延长尾矿库服务年限而导致溃坝的事故时有发生。本文介绍尾矿库延长服务年限所采取的不同技术,综合分析了不同方法的优、缺点,并提出了其应用范围及应注意的技术问题。     

Influence of Chemical Composition on Phase Transformation Temperature and Thermal Expansion Coefficient of Hot Work Die Steel

 On the basis of the uniform design method, six kinds of martensitic hot work die steels were designed. The phase transformation temperatures including Ac1, Ac3, and Ms were measured by DIL805A quenching dilatometer. The influences of the main elements on phase transformation temperatures were analyzed by quadratic stepwise regression analysis, and three corresponding equations were obtained. These equations, in which the interactions of the elements were considered, showed more effectiveness than the traditional ones. In addition, the thermal expansion coefficients of these steels in annealed state and quenched state were also obtained during the tests. The influences of chemical composition and temperature on the thermal expansion coefficient were analyzed; the equations obtained were verified by using several kinds of steels. The predicted values were in accordance with the results of the experiments.     

铸轧辊套热膨胀及热应力的有限元分析

本文在利用已有的有限差分法求解获得铸轧辊辊套温度场的基础上,采用有限元法分析了铸轧辊辊套相应的热变形和热应力。获得了热变形结果,以及在铸轧辊中产生的各种应力情况,其中第四强度理论的最大相当应力为703.7MPa,所得结果有助于解释辊套为何需采用用高强度钢材。     

固相反应烧结制备负膨胀陶瓷材料ZrW2O8

以WO3和ZrO2粉末为原料,球磨混匀后经190MPa冷等静压成形,在1200℃下固相反应烧结24h制备出负膨胀系数材料ZrW2O8.试验结果表明,采用固相反应烧结的方法能够经济有效地制备出ZrW2O8块体材料.XRD分析试样的物相组成主要为ZrW2O8,SEM观察了试样的断口形貌.万能膨胀仪测出试样在18～718℃之间的平均线膨胀系数为-5.57×10-6K-1,排水法测出试样室温下的密度为4.81g/cm3.     

箱形烟风道壳体及膨胀节设计与振动分析

采用伽辽金法分析计算空气预热器烟风道外壳平板壳体的弯矩和位移 ,确定烟风道平板的最小许可厚度。并由弹性力学方法进行了烟风道平板壳体的振动分析和膨胀节设计 ,给出了平板壳体的自振频率等参数     

压力容器加强筋板焊接接头裂纹产生原因分析

本文通过压力容器接管加强筋板焊缝裂纹产生原因的分析,提出了解决这一带有普遍现象问题的方法,并经实际运行证实了该方法的可行性。