拉坯速度对连铸大方坯凝固的影响

结合现场研究,利用显式有限差分法计算出不同工艺条件下的铸坯凝固情况;进行了拉坯速度对出结晶器坯壳厚度、铸坯表面温度、铸坯凝固终点位置和铸坯质量影响的模拟分析研究.模拟结果表明,拉速对铸坯表面温度和凝固终点的影响较大,随拉速的增大,表面温度升高,出结晶器坯壳厚度减薄,铸坯液相穴拉长.     

热轧板坯出库问题的树搜索算法

热轧板坯的出库问题是连铸-热轧生产中一个重要的组合优化问题, 然而在学术界还很少见到对该问题的研究. 对此, 提出了热轧板坯出库问题总移动次数的一个下界, 开发了一个极小化总移动次数的树搜索算法. 该算法包括一个生成初始解的贪婪算法和一个基于复合移动的递归搜索. 大量的实验和分析表明, 该树搜索算法能在较短的时间内给出板坯出库问题的满意解, 具有重要的理论意义和应用价值.

     

三维数值仿真技术在箱涵混凝土浇筑中的应用简

水利工程混凝土箱涵是一种常见的重要的输水工程建筑物型式,具有断面尺寸大、浇筑方量大、质量要求等级高等特点,不同施工工法和施工工艺,其箱涵的应力应变如何分布,对后续箱涵运行的安全、有效保证工程的耐久性、结构性能具有重大影响。本文通过三维数值仿真模型在不同分层结构混凝土施工中的应用分析．找出了不同分层浇筑混凝土箱涵的变化规律,指导了类似工程的施工。     

Effect of ultrasound treatment of AlSi5 liquid alloy on corrosion resistance

The application of power ultrasound to liquid alloys can be a simple and cost effective method to induce both degassing and grain refinement in a single step, without the need of inert gas or inoculants additions. In this paper, the treatment of liquid hypoeutectic AlSi5 alloy by ultrasound waves and its effects on microstructure were investigated. The corrosion behavior of ultrasound treated samples was compared to that of the non‐treated ones by means of immersion and electrochemical tests. It was observed that the ultrasound treated alloy offers better quality, higher mechanical properties and improved corrosion resistance, as a consequence of a more uniform distribution of the solute.     

轿车门用铝合金型材生产工艺研究

通过每个工序的多次试验，得出适用于轿车门型材的最佳铝合金成分，铸造和挤压工艺参数，保证了轿车门铝合金型材的组织、抗拉强度和弯曲成形等使用性能。     

论国产单机架四重双卷取热轧机组在我国铝加工业的推广

介绍了国产单机架四重双卷热轧机组组的技术先进性及在我国铝加工业推广的意义。     

Microstructure comparison of ZK60 alloy under casting, twin roll casting and hot compression

The microstructures of ZK60 alloy under conventional direct as-casting (DC),twin roll casting (TRC) and twin roll casting followed by hot compression (TRC-HC) were analyzed by optical morphology (OM),electron backscatter diffraction (EBSD) and X-ray diffraction (XRD).The deformation condition of hot compression is 350 ℃,0.1 s?1.The microstructural evolution under TRC-HC deformation followed by annealing at different temperatures and time was discussed.The results show that TRC provides more modified microstructure compared with DC.Twins are found in TRC processing;dynamic recrystallization (DRX),shear bands and twins are found in TRC-HC.A short annealing time has little effect on hardness,while during a long time annealing,it is found that low annealing temperatures increase the micro-hardness and high temperature decreases it.     

Studies on slip casting behavior of lanthanum strontium manganite

Dispersion conditions for slip (slurry) formulation of a powder mixture of lanthanum strontium manganite (La_0.84Sr_0.16MnO₃ - LSM) and carbon (pore former) in water was studied through detailed zeta-potential and rheological measurements. The zeta potential variation with pH for the aqueous suspensions of only LSM or carbon exhibited a maximum value in alkaline medium (−40 mV to −50 mV at a pH of 10-11), establishing the pH window for their co-dispersion for slurry formulation. A study of the viscosity variation with shear rate for the slurries with varying solid content (in the range of 45-65 wt.%) exhibited pseudo-plastic flow behavior, indicating presence of flocculates in them. The yield stress values obtained from the Casson equation reduced with decreasing solid content, indicating reduction in the flocculate strength. The slip with solid content of 50 wt.% exhibited optimum flow characteristics to form long tubes with uniform wall thickness (wall thickness 2-4 mm and length of 150-200 mm). The tubular specimens formed after controlled carbon burn out and sintering at 1400 °C for 1 h possessed about 35% open porosity. The porosity remained the same upon further sintering at 1400 °C for 8 h.     

Preparation and Properties of Biodegradable Polymer Film Based on Polyvinyl Alcohol and Tropical Fruit Waste Flour

In this study, two different types of tropical fruit waste flour, rambutan waste flour (RWF) and banana waste flour (BWF), were blended with polyvinyl alcohol (PVOH) by solution casting method. The structure of the blend film was characterised by Fourier Transform Infrared Spectroscopy. The tensile strength and elongation at break of tropical fruit waste flour-filled polyvinyl alcohol were lower, but the tensile modulus was higher, than that of PVOH film. At a similar blend ratio, the tensile properties of the PVOH/RWF film were higher than the PVOH/BWF film, but the PVOH/BWF film showed higher water uptake than PVOH/RWF film.     

横向铸造结晶器的改进

介绍一种用机械套装的热顶代替传统的手工制作的喇叭碗或硅酸铝纤维套的结晶器。具有使用寿命长、经济效益好，更有利于抑制铸锭偏析瘤的特点。同时铸造温度范围更宽，铸造速度可达２２０ｍｍ／ｓ。