Behavior of Non-metallic Inclusions in Centrifugal Induction Electroslag Castings

In order to know the behavior of non-metallic inclusions in centrifugal induction electroslag castings (CIESC), non-metallic inclusions in 5CrMnMo and 4Cr5MoSiV1 were qualitatively and quantitatively analyzed. The largest size of inclusions in the casting and the thermodynamic possibility of TiN precipitation in steel were also calculated. The results show that sulfide inclusions are evenly distributed and the content is low. The amount of oxide inclusions in CIESC 4Cr5MoSiV1 steel is close to the ESR steel and lower than that in the EAF steel, and there are some differences along radial direction. Nitride inclusions are fine and the diameter of the largest one is 3-4 μm. With the increase of the centrifugal machine's rotational speed, the ratio of round inclusions increases and the ratio of sharp inclusions decreases. According to the experiment and the calculation results, it is pointed out that the largest diameter of non-metallic inclusions in the CIESC 4Cr5MoSiV1 casting is only 6.6 μm, and [N%][Ti%] in 4Cr5MoSiV1 steel should be controlled less than 4.4× 10-5 in order to further reduce the amount and size of TiN inclusions.     

Physical Simulation to Determine High TemperatureMechanical Behavior of Continuously Cast Steels

Hot ductility and strength of Continuous casting(CC) steels at elevated temperatures from CC processeswere studied by physical simulation. The method is the hot ductility test. The design of test parameters and datainterpretation are discussed. The results show that the bulging of CC steel slabs which is caused by the mechanismof creep has great influence on the formation of central segregation and internal cracks. Creep tests including staticcreep tests and dynamic creep ones were performed at 1200 and 1300℃. Effects of strain rate and temperature onhot ductility are also discussed and a simple model is presented to explain the interaction between hardening and softening.     

Study on Oxygen Content, Inclusions and Fatigue Properties of Bearing Steels Produced by Different Processes

The metallurgical properties and fatigue life of bearing steel processed by electric furnace (EAF), ladle refining (LF-VD), continuous casting (CC) and electroslag remelting (ESR) have been investigated. The main results obtained are as follows: (1) Due to low oxygen content and dispersion inclusions in steel, the fatigue life of LF-VD-IC or CC is three times as high as that of EAF steel; (2) The oxygen content in steel produced by CC process is about 9.0× 10-6, the carbon segregation (C/C0) is from 0.92 to 1. 10 and the fatigue life of CC steel is equal to that of ladle refining ingot casting steel; (3) Although the amount of inclusion and oxygen in ESR steel is higher than that of LF-VD-IC or CC steel, the fatigue life of ESR steel is higher than that of the latter because of its fine and well dispersed inclusions.     

铸造氧化铝短纤维增强铝合金复合材料的研究

本文在国产氧化铝短纤维的基础上,研究了铸造氧化铝短纤维增强铝合金复合材料。研究结果表明,用挤压铸造技术制备氧化铝短纤维增强铝合金复合材料是可行的,和基体合金相比,所制备的复合材料具有良好的显微组织和优异的机械性能。     

A Model for Diagnosing the Formation of Internal Cracks in Continuously Cast Slabs

Internalcracksareatypeofdefectfrequentlyoccurringincontinuouslycastslabs,anditisusuallyaccompaniedbyserioussegregationandisharmfultotheuniformityandcontinuityofsteel.Ithasbeenprovedthatinternalcracksarecausedbytheexcessivetensilestrainoriginatingatth...     

微合金贝氏体抗磨钢及其性能研究

用金属类生态环境材料的研究思路 ,设计抗磨钢材料成分 ,确定其产品制备工艺 ,将微合金化理论与控铸控冷工艺相结合 ,即能获得贝氏体、马氏体和残余奥氏体基体组织。不仅可减少资源和能源消耗 ,提高金属材料的循环再生利用率 ,有效合理地利用地球上的富有资源 ,保持资源平衡 ,而且使产品的制造工艺及设备简单 ,易于操作控制 ,为成功地生产成本低廉、综合性能优良的新型微合金贝氏体抗磨钢件提供了有实用价值的理论及数据。     

钢中非金属夹杂物图像分形维数的研究

通过对304/304L不锈钢轧材中大型夹杂物和铸锭中显微夹杂物的图像进行处理,得到夹杂物边界的二值图像。采用计盒维数法对夹杂物轮廓的分形维数进行计算与分析,算法利用MATLAB编程实现。结果表明,夹杂物的分形维数与其组成和熔点密切相关,低熔点的Al2O3-SiO2-CaO系复合夹杂的形貌多为球形或类球形,其分形维数较小;高熔点的Al2O3夹杂物与SiO2夹杂物的形貌多为不规则形,其分形维数较大。     

挤压铸造在大型复杂铝合金铸件生产中的应用

本针对结构复杂、重量较大的耐压铝铸件的生产特点，分析了利用挤压铸造工艺进行生产的可行性，详细地提出了设计方案，并指出了设计中应注意的重要问题。     

基于进化算法的组浇计划及参数正交设计

对于一个复杂问题的解决，至少需要完成两项工作，一个是选取解决该问题的最优算法，另一个是调整算法中的参数使之性能达到最优．利用进化搜索算法－遗传算法解决炼钢－连铸组浇计划问题，并对遗传算法中的主要参数进行了正交设计，仿真结果表明了算法的有效性和参数设置的必要性．     

炼钢 -连铸组浇计划的两阶段求解算法

根据炼钢 -连铸组浇计划当浇次数已知、无剩余炉的组浇计划模型的求解算法 ,本研究给出当浇次数未知、有剩余炉的组浇计划模型的求解算法     

易切不锈钢中非金属夹杂物在切削中的变形特性

采用金相显微镜、扫描电镜和能谱分析等手段,对OCr16Ni10CaS复合易切奥氏体不锈钢(牌号F176、F176B)的大量切屑根部磨片进行了观察与研究,在切削过程中,此钢中的非金属夹杂物流经不同变形区时,其变形特点是不同的;此钢中的氧化夹杂物主要是由MnS和FeS包裹着的多元氧化物CaO、MgO、Al_2O_3、SiO_2、MnO,在刀-屑接触区的高温高压作用下,可由刃口及滞流层的微裂纹中被挤出并涂抹到刀具表面上,为形成刀具表面覆盖膜创造了必要条件。     

马钢轴承钢试制的非金属夹杂物控制的精炼工艺研究

采用理论分析结合生产经验的方法,确定马钢特钢GCr15轴承钢的精炼渣组分、钢中[Ti]和[N]含量上限以及真空循环时间和浇铸前软吹时间等关键工艺参数,实现对钢中非金属夹杂物的有效控制,成功试制了T[O]5ppm、D类夹杂评级≤1.0级和DS类夹杂物≤1.0级的高品质GCr15轴承钢。由于凝固偏析的作用,在[Ti]和[N]含量较低的条件下,不能避免凝固过程中析出Ti N类夹杂。     

42CrMo钢中夹杂物在裂纹成核和扩展中的作用

通过平板拉伸实验，用准动态方法观察了４２ＣｒＭｏ钢中裂纹在夹杂物上成核和扩展，得出开裂应变与夹杂物类型和尺寸的关系，裂纹成核方式是夹杂物／基体界面开裂和夹杂物自身开裂．     

X射线实时成像在铝合金压铸件上的应用

针对快速准确检测铝合金压铸零件内部质量的问题,采用x射线实时成像系统对铝合金压铸件凸轮轴盖进行内部质量检测试验．依据X射线实时成像的工作原理,利用图像呈现的灰度对零件内部缺陷进行评价．采用线切割方法获取零件内部缺陷截面,验证图像缺陷和实际缺陷的对应关系．通过试验发现不同类型的实际缺陷对应实时成像图像不同的缺陷形貌．缩松在影像中呈羽毛状或海绵状,缩孔在影像中呈树枝状较大的影像,气孔在影像中呈现清晰的圆形或椭圆形轮廓．x射线实时成像探伤能够准确反映铝合金压铸件内部缺陷特征,精确控制产品质量．     

车轮钢精炼-连铸过程氢含量变化规律现场试验研究

采用离线测定的方式对车轮钢精炼-连铸过程氢含量的变化规律进行了现场试验,确定车轮钢增氢的关键环节,为制定车轮钢防增氢措施提供依据。     

不锈钢高速连铸中结晶器的热流计算

在高效连铸过程中,结晶器的传热效率起着至关重要的作用。在进行加拿大国家自然科学基金资助的高速连铸的战略性研究项目时,在Ａｔｌａｓ Ｓｔｅｅｌ钢铁公司的方坯连铸机上进行了１次工业试验,目的是研究高速连铸不锈钢时结晶器的热流变化。试验中,结晶器４壁共安装了４２个热电偶。不同工艺条件下的温度信号以１０Ｈｚ的频率记录在计算机中,根据每点的平均温度,针对ＩＨＣＰ（Ｉｎｖｅｒｓｅ Ｈｅａｔ Ｃｏｎｄｕｃｔｉｏ     

Simulation of the continuous casting process in a mold of free-cutting steel 38MnVS based on a MiLE method

A new method called mixed Lagrangian and Eulerian(MiLE)method was used to simulate the continuous casting process in a mold of free-cutting steel 38MnVS.The simulation results are basically in agreement with experimental data in the literature,achieving the three-dimensional visualization of temperature distribution,melt flow,shell thickness,and stress distribution of blooms in a mold.It is shown that the flow velocity of steel melt becomes smaller gradually as the casting proceeds.When the flow reaches a certain depth,two types of flow patterns can be observed in the upper zone of the mold.The first flow pattern is to flow downwards,and the second one is to flow upwards to the meniscus.The comer temperature is higher,and the thickness is thinner than those in the mid-face.The effective stress in the comer area is much bigger than that in the mid-face,indicating that the comer area is the dangerous zone of cracking.     

7055铝合金半连续铸造过程区域水冷工艺数值模拟

建立了7055铝合金半连续铸造过程的数学模型,采用了有限元模拟软件Procast对铸造过程进行模拟,模拟过程还采用了Procast模拟连铸的MILE算法.通过在结晶器下方设置区域冷却装置刮水板,使半连续铸造的二次冷却水在挡水板位置被阻挡和分流,实现区域冷却效果,保证铸造过程中刮水板下方铸坯自然空冷,铸锭利用自身余温＂低温回火＂,有效降低了铸造内应力,抑制了铸坯开裂.仿真了刮水板不同位置的温度场与应力场的变化情况,模拟结果显示,适当减小区域冷却范围,可有效减小表面裂纹和中心裂纹产生的倾向性.     

硫酸铝浸渍活性氧化铝球吸附饮水中的高浓度氟

硫酸铝浸渍活性氧化铝球（AIAA）是饮水除氟领域常用的吸附剂,它对氟的吸附性能受各种因素的影响。静态吸附通过改变AIAA质量与氟溶液体积比（m（AIAA）：V）（2～40 g.L-1）、氟的质量浓度（ρ（F））（2～100 mg.L-1）、pH值（4～10）、温度（11～33℃）和时间等实验参数,研究这些因素对AIAA吸附除氟的影响。在11～33℃的温度范围内、pH值变化为4～10之间时,当m（AIAA）：V为20 g.L-1,3 h内处理ρ（F）为10 mg.L-1水溶液其氟的去除率可达90%以上,足以保证其满足饮用水的含氟标准。利用Langmuir和Freundlich模型对吸附数据进行了拟合研究,结果表明：在ρ（F）为2～100 mg.L-1、pH=5～10、温度11～33℃范围内,Langmuir线性拟合模型是最优拟合方式;而当溶液氟质量浓度为2～1 000 mg.L-1或2～100 mg.L-1且pH为4时,Freundlich非线性拟合模型是最优拟合方式。AIAA吸附容量随溶液氟质量浓度升高、pH降低及温度升高逐渐增加。