悬索桥主缆用Φ5.1mm 1860MPa热镀锌钢丝的研制

介绍Φ5.10mm1860MPa悬索桥主缆用镀锌钢丝技术指标,从盘条的选择、表面处理、冷拉拔、热镀锌、规圆处理等方面对其主要生产工序进行研究分析,指出各工序需重点控制的内容。Φ5.1mm1860MPa热镀锌钢丝生产工艺:铅浴脱脂温度控制在400℃以上;采用盐酸加热酸洗,温度控制在40℃以上;助镀采用ZnCl2和NH4Cl的复盐作溶剂,溶液温度控制在60℃以上;热镀锌锌液温度为440～460℃;生产线Dv值为90～100mm.m/min;采用辊式矫直器和大变形方案实施钢丝矫直;去应力回火温度在380℃以下。给出Φ5.1mm1860MPa热镀锌钢丝的实际检测数据,对比其技术指标认定宝钢集团生产的桥梁缆索专用盘条适应悬索桥主缆用热镀锌钢丝生产需求。     

Preparation and characterization of Si3N4/SBR nanocomposites with high performance

In this work, native silicon nitride (Si₃N₄) nanoparticles were modified by macromolecular coupling agent (LMPB-g-MAH) which was designed and synthesized according to the chain structure of styrene butadiene rubber (SBR), and Si₃N₄/SBR nanocomposites were prepared by two-segment mixing process. The structure and surface properties of modified Si₃N₄ nanoparticles were characterized by Transmission Electron Microscope (TEM), Fourier Transform Infrared Spectroscopy (FTIR), size distribution analyzer, and contact angle measuring instrument. The effect of different dosage of nano-Si₃N₄ on Si₃N₄/SBR nanocomposites was also systematically studied. It can be got that LMPB-g-MAH can effectively inhibit the agglomeration and improve the hydrophobic property of Si₃N₄ nanoparticles. It also can be found that modified Si₃N₄ nanoparticles brings well physical and dynamic mechanical properties, aging resistance, oil resistance, wear resistance, and low rolling resistance to SBR, especially, when the dosage is 0.5–1.5 phr, the best overall performance of Si₃N₄/SBR nanocomposites can be achieved.     

A comparative study of tertiary wastewater treatment by physico-chemical-UV process and macrofiltration–ultrafiltration technologies

A comparative study was undertaken of the economic costs and quality of effluents obtained from physicochemical-UV and macrofiltration–ultrafiltration as municipal wastewater tertiary treatments. A physicochemical-UV urban wastewater treatment system was designed for the study. Pre-treatment to UV radiation disinfection consisted of coagulation with alumina (100 mg/L), sedimentation by sludge-blanket sedimentation tank (0.8 m³/m² h) and filtration by sand-pressure filter (5.0 m³/m² h). The ultrafiltration module was equipped with flat polyvinylidenefluoride membranes (0.05 μm pore size), with pre-treatment carried out by a sandpressure filter (8.0 m³/m² h). Both systems obtained effluent of excellent physico-chemical quality (91% removal of suspended solids and 99% turbidity removal) and microbiological quality (total absence of nematode eggs, coliforms, E. coli and coliphages). However, while physico-chemical quality remained constant in both systems, microbiological quality of effluent from the UV-disinfection process was shown to depend on the quality of influent, particularly with regard to transmittance. By contrast, microbiological quality remained constant in the case of membrane technology. Other control parameters such as particulate analysis confirmed the higher quality of ultrafiltration effluent in comparison with the physico-chemical-UV process. With regard to costs, both technologies present similar variable costs, while fixed costs of the membrane installation are double those of the physico-chemical-UV process, owing particularly to the high cost of the installation itself.     

Effect of rare earths on impact toughness of a low-carbon steel

Studies of an industrial low-carbon steel (B450NbRE) suggest that the impact toughness is unexpectedly low under its practical service, probably resulting from the unstable recovery of rare earths (RE) in steelmaking. The purpose of this work is to investigate the effect of RE on the impact toughness in low-carbon steel. The B450NbRE steels with content of 0.0012–0.0180 wt.% RE were produced by vacuum induction furnace. The impact toughness and microstructure were investigated after hot rolled. The Gleeble-1500 thermal simulator was used to validate the effect of RE on the microstructure. The results indicate that the microstructure of hot-rolled steels is characterized by polygonal ferrite, quasi-polygonal ferrite, bainite and pearlite. The impact toughness increases with RE contents reaching the peak with content of 0.0047 wt.% RE, such a change exhibits the same rule as the case of the ferrite amount. However, this improvement in impact toughness is not only due to an increase in ferrite amount, but also the fine grained structure and the cleaner grain boundaries. And content of 0.0180 wt.% RE is excessive. Such an addition of the RE resulted in the martensite precipitates at the grain boundaries, which are extremely detrimental to impact toughness.     

冷弯厚壁型钢轴压构件设计可靠度分析

在材性试验的基础上对冷弯厚壁型钢进行了轴压承载力试验及有限元分析。试验中发现：对于长细比较大、板件宽厚比较小的试件,破坏模式为整体失稳;对于长细比较小、板件宽厚比较大的方管柱,其破坏过程首先是柱中部产生很小的弯曲变形,随着荷载增大,整体弯曲变形也逐渐增大,并引起方管板件的局部屈曲。采用ANSYS软件进行有限元分析,其结果与试验结果接近,表明将残余应力引入有限元模型对冷弯厚壁型钢构件进行分析具有较高的精度。在此基础上,利用收集到的26组不同牌号、不同截面冷弯厚壁型钢的试验数据建立有限元模型,并引入已有的残余应力模型进行了大量的有限元分析,得到了多组冷弯厚壁型钢轴心受力构件的承载力。对冷弯厚壁型钢构件进行了设计可靠度分析,提出了Q235、Q345冷弯厚壁型钢的抗力分项系数和强度设计值的建议值,可为相关技术标准的修编提供依据。     

应用状态监测技术提高设备管理水平

设备状态监测与故障诊断技术是一种预测故障发展趋势的技术,根据设备监测方式不同可分为离线定期监测、在线监测离线分析、自动在线监测3种。设备状态监测技术的基础工作主要是指监测手段和经验的积累,包括监测参数的选择、数据库建立和测量点选择、数据的采集与分析。运用该技术对高速线材轧机设备中的精轧机组、三重式增速箱、夹送辊及吐丝机等关键设备进行监测及诊断,取得较满意的效果。     

水浸探头对1Cr21Ni5Ti钢棒材底波监控的影响

分析了水浸探头对1Cr21Ni5Ti不锈钢棒材底波监控的影响因素,采用了不同频率和不同聚焦类型的水浸探头,设置了不同距离的水程,利用LS200B型设备对被检棒材进行超声检测,使用PROCESS图像评估软件对C扫描图像进行分析。结果表明,1Cr21Ni5Ti棒材在圆周方向底波波幅是变化的;探头频率、聚焦类型和水程距离都会影响被检棒材的底波波幅水平。     

Welding of twinning-induced plasticity steels

This work focuses on the technical and technological aspects of fusion welding of high-manganese steels exhibiting twinning-induced plasticity (TWIP) for both similar and dissimilar joints. Changes in the alloy chemistry resulting from evaporation and dilution are discussed with respect to stacking fault energy and austenite stability. The influence of fusion welding on grain size and strength is also discussed. Conclusions are drawn with respect to optimization processes for fusion welding of TWIP steel.     

Sintering characteristics of fluxes and their structure optimization

Sintering characteristics of common fluxes and sintering blending ores, such as mineralization capacity, liquid generation capacity, consolidation strength, were examined to master the behavior and effect of fluxes in sintering. Based on fundamental studies, sinter pot tests were carried out to obtain the principles of optimizing the sinter flux structure. The results showed that strong mineralization capacity, liquid phase generation capacity, and consolidation strength were obtained as sintering blending ...     

A submicron mild steel produced by simple warm deformation

One simple deformation process, through which a submicron ferrite grained mild steel was fabricated, was introduced. According to the transmission electron microscope images of the microstructures, most of the boundaries formed during the process might be low angle boundaries, which means that most of the ultrafine grains are subgrains. This deformation process is attractive because: (1) the necessary strain was only 1.5, (2) the deformation resistance decreased due to higher rolling temperature, and (3) the as warm-rolled mild steel had a microstructure with equiaxed grains of 0.7 μm in average diameter. The result of mechanical tests indicates that better properties, with comparison to its coarse-grained counterpart, were obtained, including doubled yield strength, high hardness, good work hardening and reliable elongation. Cross effect was observed during tensile process and interpreted from point view of conventional dislocation movement.