The Study on 400 MPa Class Plain Carbon Structure Steel

New generation of structure steel has been developed to meet the uninterruptedly increasing needs of the economic construction and development of society, and such material is characterized by ultra-fine grain. In this paper, 400MPa class plain carbon structure steel has been studied, making its yield strength doubled and service life doubled on the basis of good comprehensive properties in large quantity utilization. The deformation behavior and the stain induced transformation of SS400 steel at different temperature were investigated in the laboratory, and the industrial rolling test was carried out in 2 050mm HSM of Baosteel. Not only the laboratory studies but also the industrial test show that the technical route of the experimentis correct and the industrial test results on the basis of low carbon plain steel indicate that the grain size of ferrite was near to 4 ～ 5 μm, elongation was more than 30% , impact property was good, the yield strength can reach 400 MPa.     

压缩波导隔离器设计

提出了一种压缩波导隔离器的设计结构和原理，对铁氧体样品的理论计算和实验结果完全相符，并给出了１３．５￣１３．９ＧＨｚ隔离器的实验结果和测试曲线。     

Metallographic Characterization of the Microstructure of Tool Steels

Examination of selectively etched tool steel microstructures by light microscopy provides more information than standard etchants, such as nital, picral or Vilella‘s reagent. Further, the images are more suitable for quantitative measurements, especially by image analysis. Specimens must be properly prepared, damage free, if selective etchants are to be applied successfully. A number of etchants have been claimed to selectively etch certain carbides in tool steels. The response of these etchants has been evaluated using a variety of well-characterized tool steel compositions. While many are selective, they are often selective to more than one type of carbide. Furthermore, their use in image analysis must be evaluated carefully as measurements showed that the amount and size of the carbides are often greater after selective etching as many of these reagents outline and color or attack the carbides. Selective etching of the matrix, leaving the carbides unaffected works well, but no one etchant will cover the broad spectrum of tool steel compositions. No etchant has been found that will color retained austenite in tool steels and image analysis of retained austenite in tool steels are always much lower than by x-ray diffraction unless retained austenite is the dominant phase present in grossly over-austenitized steels.     

巨厚油层不同注水方式模拟研究

介绍了一种二维可视物理模型,该模型具有可视性强的特点,可直接观察到注入水在多孔介质中的流动情况.针对辽河冷家油田储层特征及原油性质的差异,在室内建立的二维可视物理模型中进行了多油层同时注水开发、上返式开采和底水托浮式开采的模拟研究,并对比研究了不同注水方式下的开发效果及其开采机理.     

Diffusion of18O in massive Cr2O3 and in Cr2O3 scales at 900°C and its relation to the oxidation kinetics of chromia forming alloys

The lattice and grain-boundary diffusion coefficients of¹⁸O atP _{O 2}=0.1 atm and at 900°C were determined in massive Cr₂O₃ and in Cr₂O₃ scales which were grown on a Ni–30Cr alloy. The diffusion profiles were established by SIMS and analyzed considering two domains in the case of polycrystalline Cr₂O₃ (massive or scales), the first one relative to apparent diffusion and the second to grain-boundary diffusion. A ridge model is proposed for Cr₂O₃ scales to modify thef value, fraction of sites associated with the grain boundary. With such a model,f is equal to 0.0006 and 0.0005 for the scales formed during 15 hr and 165 hr, respectively. The oxygen-lattice diffusion coefficients determined in Cr₂O₃ scales are in very good agreement with those in massive Cr₂O₃. With some assumptions, our diffusion data lead to a calculated parabolic oxidation constant equal to the experimental one. Scale growth occurs by countercurrent diffusion of oxygen and chromium, mainly by grain-boundary diffusion.     

Determinations of the non-recrystallization temperature for X52 steel produced by compact slab process combined with direct hot rolling

Deformation comprises not only dimensional accuracy but also the control of the final microstructure and mechanical properties. Deformation below the non-recrystallization temperature (T _nr) is important to design the proper rolling schedule to avoid grain growth in the final stages of rolling. The determination ofT _nr for Nb-bearing carbon steel with a compact slab process mill log is carried out depending upon the Misaka concept calculation. A comparison among different formulas for predicting theT _nr was conducted using Misaka, Bratto, and Jonas equations. The Misaka equation depends on the chemical compositions and deformation parameters including dynamic and metadynamic recrystallization. The Bratto equation considers only the steel chemical composition. The Jonas equation depends only on the accumulated strain. The Bratto equation gives a large value ofT _nr, while the Misaka equations show a moderate and accurate value in relation to the Jonas results, which depend on torsion tests. The effect of strain accumulation on dynamic recrystallization is investigated to predict the final grain size of ferrite.     

含La~(3+)的Ni-Zn铁氧体的微观结构和电磁性能

本文通过在 Ni-Zn 铁氧体中掺入 La_2O_3后,材料的电磁性能、温度特性和微观结构所发生的变化,研究了 La~(3+)离子的掺杂效应和作用机制。实验表明:Ni_(0.41)Zn_(0.60)Sn_(0.01)Cu_(0.02)Fe_(2.04-X)La_xO_(4±δ)在x<0.010时,La~(3+)离子能细化晶粒;x>0.010时,La~(3+)离子使晶界模糊,晶粒尺寸增大;不同温度区域的电子激活能 E_ρ呈现出明显的差异。La~(3+)离子对电阻率ρ的贡献主要是提高了晶界电阻率。     

大掺量粉煤灰混凝土在大体积结构中的应用

对国贸三期主塔楼大体积底板工程中使用的大掺量粉煤灰混凝土畅行无阻 水化温升、力学性能和体各人稳定性的检测。结果表明，混凝土的水化温升较低，60d抗压强度为58MPa，满足工程设计中的要求，且体积稳定性良好。大量粉煤灰的掺入，有效降低了混凝土的水化热。由于大体积混凝土内部温度仍高于环境温度，其早期强度和弹性模量仍有较快增长。     

磁铁矿在不同气氛下的烧结行为

采用－红外加热炉在模拟烧结温度制度的条件下，研究了磁铁矿在工业氮气及氧化气氛中的烧结行为。结果表明，在工业氮气中铁酸钙可以由磁铁矿直接生成。以该方式从烧结混合料中形成的铁酸钙含量甚微，所形成的烧结矿则由磁铁矿和硅酸盐组成。氧化气氛下烧结使赤铁矿和铁酸钙成为烧结矿的主要矿物。故磁铁矿烧结的关键在于将磁铁矿氧化，改变成矿过程而生成良好结构的烧结矿。在磁铁矿氧化不能充分发展时，配加赤铁矿是改善磁铁矿烧结     

针状铁素体的物理冶金学（待续）

针状铁素体能明显改善高强度低合金钢焊缝的力学性能，提高其抗环境损伤的能力，具有重要的工程意义。作者利用扫描电镜和透射电镜研究了针状铁素体的组织形态，并观察到高角度晶界结构和相界周围的“唇”带村度，探讨了其抗解理断裂的机理。并根据国内外的研究报道，综述了形成针状铁素体所必需的工艺条件和合金化条件。