Microstructure and properties of Al-0.70Fe-0.24Cu alloy conductor prepared by horizontal continuous casting and subsequent continuous extrusion forming

A novel process for manufacturing A1-0.70Fe-0.24Cu alloy conductor was proposed, which includes horizontal continuous casting and subsequent continuous extrusion forming （Conform）. The mechanical properties, electrical conductivity and the compressed creep behaviour of the alloy were studied. The results indicate that the Conform process induces obvious grain refinement, strain-induced precipitation of AI7CuzFe phase and the transformation of crystal orientation distribution. The processed alloy has good comprehensive mechanical properties and electrical conductivity. Moreover, a better creep resistance under the conditions of 90 ~C and 76 MPa is shown compared with pure A1 and annealed copper, and the relationship between primary creep strain and time may comply with the logarithmic law. The enhanced properties are attributed to the grain refinement as well as the fine and homogeneously distributed thermally stable A1Fe and A17Cu2Fe precipitation phases.

Measurements of suspended particulate matter with laser in-situ scattering and transmissometry in the Jiaozhou Bay in China

A laser in-situ scattering and transmissemetry probe （LISST - 100） was used to estimate the spatial variations of suspended particle （aggregate） distribution, volume concentration and beam attenuation in the Jiaozhou Bay, Qingdao, China on 18 July 2003. One study site was located at the mouth （Sta. J1 ）, with the other being within the inner bay （Sta. J2）. Measurements of total suspended matter （TSM） and chlorophyll fluorescence and sampling of bottom sediments were carried out simultaneously. On the basis of the field data, the in-situ particle effective density, settling velocity and flux, and particle projected surface area （PSA） were estimated. The results demonstrate that both profiles have similar particle size distributions from surface to bottom within the water columns. Mean particle diameters for Stas J1 and J2 are 38 - 74 and 1 - 20 μm, respectively, particles within these ranges dominate over the particulate components. Suspended particle volume concentrations increase with water depth, with spikes near the bottom. At Sta. J1, the mean size of bottom sediments and those of suspended particles at 10.8 m below the water surface are almost the same, as well as their size distributions. This observation suggests that a special affinity exists between bottom sediment and suspended particles. In addition, the estimates show that the effective density, settling velocity and flux are higher in the innet bay. Beam attenuation coefficient correlates well with the volume concentration, positively. It is inferred that the optical scattering was mostly caused by 1 - 250 μm components, among which the particles finer than 20 μm dominate the beam attenuation. The PSA appears a proxy for the leaving reflectance estimation.

Process for improving the ladle free- opening rate for high aluminum steel in continuous casting

Steel 20Mn23AlV is a type of high aluminum steel with a very low ladle free-opening rate. The aluminum composition of 20Mn23AlV ranges from 1.6% to 2.45% ,which is significantly higher than other types of steel. According to the real condition of 40 t ladle in steel-making plant of Baosteel Special Steel Company, previous works show that the key factors affecting the ladle free-opening rate of high aluminum steel in continuous casting are：sand material, accessories baking, ladle nozzle cleaning, the process and amount of adding sand, and the rate of argon stirring during refining. Therefore, improving the ladle filler sand quality, baking all of the raw materials, controlling the addition of ladle filler sand, cleaning the ladle nozzle, and optimizing argon stirring during the refining process can resolve the problem of a low ladle free-opening rate of high aluminum steel caused by the long ladle time of liquid steel.

The EVA plastic film for V-process and steel castings by V-process in China

EVA plastic film is the key material for V-process. Through decades of research, special EVA film for V-process has been produced. The film has adequate elongation; its maximum is about 800% in longitudinal direction and 750% in transversal direction. The single width of the film is 2.8 m and the double width is 5.6 m, which is the widest sheet film for V-process in China. Sheets with different thickness ranging from the thickest 0.35 mm to the thinnest 0.08 mm can meet different demands in China. The film can be used not only for V-process of iron castings, but also for the manganese steel railway frog, steel rocking support and side frame castings for train and the steel bridge box for engine truck.

Fabrication and Studying the Mechanical Properties of A356 Alloy Reinforced with Al₂O₃-10% Vol. ZrO₂Nano-particles through Stir Casting

Al2O3-ZrO2 with a high level of hardness and toughness is known as ceramic steel. Due to its unique properties it can be used as a reinforcement in fabrication of metal matrix composites. In this study, nanoparticles of Al2O3-10% ZrO2 with an average size of 80 nm were used to fabricate Al matrix composites containing 0.5, 1, 1.5 and 2 wt.% of the reinforcement. The fabrication route was stir casting at 850?C. There is no report about usage of this reinforcement in fabrication of composites in the literature. The microstructures of the as-cast composites were studied by scanning electron microscope (SEM). Density measurement, hardness and tensile properties were carried out to identify the mechanical properties of the composites. The results revealed that with increasing the reinforcement content, density decreased while yield, ultimate tensile strength and compressive strength increased. Also, hardness increased by increasing the reinforcement content up to 1 wt.% Al2O3-10% ZrO2 but it decreased in the samples containing higher amounts of reinforcement.

悬浮熔炼-铜模吸铸法制备Cu_(50)Zr_(42)Al_8块状金属玻璃

采用悬浮熔炼-铜模吸铸法制备了Cu基块状金属玻璃,对直径5.0 mm的Cu50Zr42Al8三元合金圆棒利用X射线衍射(XRD)和差示扫描量热法(DSC)对合金的结构和热稳定性进行了测定.实验结果表明,该合金圆棒的组织为明显的非晶相,玻璃转变温度Tg、晶化温度Tx的值分别为730 K与778 K,过冷液相区宽度ΔT值为48 K,临界冷却速度Rc为25.5 K/s,表明该合金具有较强的玻璃形成能力,悬浮熔炼-铜模吸铸法是一种适合于制备块状金属玻璃的方法.

Al-5%Fe合金的悬浮铸造

研究了悬浮铸造工艺对Al-5%Fe合金中的初生Al3Fe相形貌的影响。实验表明,采用Al-10%Fe混合粉末、Al-20%Fe混合粉末作为悬浮剂可以在一定程度上细化合金的铸态组织:未加悬浮剂时,合金中的组织为粗大的针状和花朵状;加入悬浮剂后,组织演变为较短小的针状、短杆状和颗粒状。

本钢235mm×265mm连铸坯生产SA-182F12C1.1钢的工艺实践

本文介绍了本钢特殊钢厂采用40 tEBT-LF-VD-3流235mm×265mm方坯连铸-热轧工艺生产Φ85mmSA-182F12C1.1锅炉吊杆钢材。通过对炼钢过程的成分控制,严格中包钢水过热度,稳定过程拉速,采用结晶器弱冷制度连铸工艺生产该钢种,铸坯质量和轧后钢材性能满足标准要求,达到了取代模铸生产的目的。

铸造车间空中移动式烟气捕集罩气流组织优化研究

因铸件浇注工序产生烟气的污染源位置不固定、源强变化大、实施污染气体捕集的空间位置不足等问题,成为铸造车间营造职业卫生环境的难点。设计了一套空中移动式烟气捕集罩,采用数值模拟的方法研究了捕集效率的影响因素。结果表明,增设捕集罩后可以提高捕集范围内风速约0.1 m/s,送风风速为2 m/s时,捕集效果最好;污染源温度为200℃时的颗粒物捕集率比温度为800℃时的捕集率提高19.7%,污染源位于捕集罩正下方时的颗粒物捕集率比位于侧方4 m处的捕集率提高9.9%,污染源直径为1 m时的颗粒物捕集率比直径为3 m时的捕集率提高35.8%。通过本研究可为铸造车间空中移动式捕集罩的工程应用提供参数支撑。

公路桥梁预应力连续箱梁施工中的挂篮悬浇技术研究

为研究挂篮悬浇技术的工艺要点和应用措施,文章以东营至青州高速公路改扩建工程中小清河特大桥为依托,重点分析了挂篮设计、挂篮拼装、挂篮预压、悬灌施工、预应力张拉等关键工序,提出了质量控制措施(注意事项)。结果表明,该工程预应力连续箱梁制订的挂篮悬浇施工方案合理可行,施工全程安全状况良好,工程质量达到了优良等级。

高速公路桥梁挂篮悬浇施工安全技术

为了给高速公路桥梁挂篮悬浇作业的安全开展提供一些借鉴,利用案例分析法,简单介绍了高速公路桥梁挂篮悬浇项目,分析了高速公路桥梁挂篮悬浇作业安全水平,论述了高速公路桥梁挂篮悬浇安全技术应用方案,并总结了安全技术的应用效果。得出:高速公路桥梁挂篮悬浇作业的安全水平不高,技术人员可以制定并实施针对性安全技术方案,确保高速公路桥梁挂篮悬浇作业的安全开展。

Study on the liquid metal flow field in FC-mold of slab continuous casting

The flow pattern and the velocity distribution of a liquid metal in the flow control mold （FC-mold） were investigated with a mercury model by analogy to the molten steel during continuous casting. The velocity measurement was conducted by the ultrasonic Doppler velocimeter （UDV） under various magnetic distributions and flux densities. The impingement intensity and the scouring intensity of the liquid metal to the narrow wall of the mold were calculated based on the measured data, and the influence of the magnetic flux density on the liquid metal flow in the mold was analyzed. The results showed that the surface of the liquid metal became more active when only the lower magnet was assembled, and the surface fluctuation was suppressed when further applying the upper magnetic field. It was indicated that when the upper and lower magnetic flux densities were 0.18 T and 0.5 T, respectively, the optimum conditions could be obtained, under which the free surface fluctuation could be suppressed, and a flow recirculation could rapidly form.

混凝土连续梁挂篮悬臂施工技术的研究

本连续梁0#段采用在墩顶现浇施工并与墩身固结的方式,悬臂段从已经浇筑的0#段开始,采用挂篮逐步向前悬臂施工。本文针对该连续梁挂篮悬臂施工的要求对挂篮进行设计,以及对挂篮悬臂施工工艺和混凝土悬臂浇筑展开系统论述,为全面提高连续梁建设效率和安全性提供技术参照。

悬浮铸造工艺对EPC铸造低铬白口铸铁性能的影响

针对常规EPC铸造生产低铬白口铸铁时综合性能较差的问题 ,采用悬浮铸造工艺将悬浮剂置于EPS模中 ,充型过程中悬浮剂均匀分布于铸型中 ,可改变金属液的结晶凝固特性 ,细化铸铁组织 ,并使部分微区内碳化物的类型发生质的变化 ,结果使低铬白口铸铁的综合性能得以显著提高。与常规方法相比 ,低铬白口铸铁的冲击韧性提高了2 4 5 % ,硬度提高了HRC4～HRC4 5 ,相对耐磨性提高了 35 %。

悬浮铸造高锰钢的组织与性能研究

本文采用局部悬浮铸造工艺，通过金相、ＳＥＭ、ＴＥＭ、ＥＤＡＸ等实验方法，对悬浮部分的高锰钢组织与性能进行了研究，同时还探讨了悬浮铸造对高锰钢组织与性能的影响机制。研究结果表明：用该工艺悬浮铸造的高锰钢铸件（粉碎机锤头），经工业性实验证明，其使用寿命是原高锰钢铸件１．８倍。

机车抱轴箱随机应力谱下的疲劳寿命预估研究

针对机车铸钢抱轴箱在运行中产生疲劳裂纹的现象,笔者对机务段检修和返厂检修的抱轴箱进行了调研,认为裂纹长度服从正态分布。对抱轴箱及其改进结构进行了有限元分析,其应力最大部位与发生裂纹部位一致。通过动应力实测获取抱轴箱危险部位的应力谱,用局部应力-应变法结合断裂力学方法估算了抱轴箱的疲劳总寿命,并与名义应力法计算结果进行了比较。结果表明,2种方法所得的疲劳总寿命基本是一致的,用局部应力-应变法计算机车抱轴箱裂纹萌生寿命是一种合理的方法,而大的铸造缺陷是抱轴箱产生裂纹的最主要原因。最后采用统计方法得到了裂纹扩展破坏的累积失效概率函数。

悬浮石墨对灰铸铁罐笼衬套的影响

从煤矿竖井提升罐笼衬套的实际服役条件出发,采用普通灰铁、悬浮石墨灰铁、杂铜三种材质试样与钢丝绳具有同样材质对磨付之间相互磨损来模拟实际钢丝绳与衬套之间的相对运动,分析衬套耐磨性。并对悬浮石墨铸造灰铁中的石墨形态、基体组织、力学性能及滑动摩擦特性进行分析,研究其磨损机理。研究表明,加0.3%石墨粉进行悬浮铸造,并经退火处理的灰铸铁是一种价格低廉、耐磨性好、与钢丝绳磨损量小的新材质,适合代替杂铜制造的罐笼衬套。

磁悬浮灌封胶新配方的研制

针对经高低温循环处理后定子磁芯材料齿根处开裂的技术难题,开展径向悬浮定子组件灌封胶新配方的研制攻关。根据径向悬浮定子组件的结构特点,要求灌封胶既具有良好的韧性,能耐高低温冲击,又要求具有刚性,保证加工精度的要求,这本身就是一对矛盾,是解决问题的关键和难点所在。通过工艺试验,提高环氧树脂灌封胶的综合性能,自主研制出灌封胶新配方,有效解决了定子磁芯高低温处理后自身开裂的问题。现新配方已成功地应用于实际批量生产中,对近二年所有批次采用新配方灌封的径向悬浮定子组件进行全面质量跟踪、计量检测和数据统计,产品的成活率由以前的25%～35%提高到90%以上,有效解决了磁悬浮的生产瓶颈问题,为我所科研生产提供了有效的技术保障。

悬浮铸造、半固态铸造与固液混合铸造

本文概述了悬浮铸造、半固态铸造和固液混合铸造工艺的基础理论研究,分析探 讨了这三种特别具有发展前景的新型技术及加工工艺的特性及工程应用。

2021年国外空空导弹发展动态研究

全面介绍了2021年国外空空导弹最新发展情况,重点论述了美国的AIM-9X、AIM-120、“远射”项目、新型空空导弹技术,欧洲的ASRAAM、IRIS-T、FCAAM、MICA NG、“流星”,俄罗斯的“产品”300M,以色列的“怪蛇”-5和I-Derby ER,印度的“阿斯特拉”等空空导弹最新研制进展和试验情况,最后总结了空空导弹的最新发展特点。