优化脱氧工艺提高38CrMoAl连浇成功率

研究了连铸38CrMoAl钢夹杂物类型和形成原因。结果表明:通过对电炉、LF炉、VD炉脱氧制度的优化以及连铸过程防止钢液二次氧化,有效减少了钢中Al2O3类型非金属夹杂物。优化工艺后生产的38CrMoAl钢连铸炉数达到9连浇,夹杂物废品率<1%。     

降低精炼钢钢中夹杂物的研究

介绍了特殊钢锭的生产工艺及产品质量现状,对钢中夹杂物的影响进行了研究.通过脱碳、脱氧、脱硫,控制软吹时间和废钢质量等措施,有效地减少钢中夹杂物数量,提高钢锭质量.     

铝对含钛微合金钢成分控制及夹杂物形成的影响

自主设计了不同Al含量的含钛微合金钢,采用火花源光电直读光谱仪检测了每炉钢的化学成分,分析了Al含量对试验钢中O和Ti含量的影响规律;利用OM、SEM观察了试验钢夹杂物形貌并进行了能谱分析,研究了Al含量对试验钢夹杂物形成的影响规律。研究结果表明：随着Al含量的增加,钢中Ti氧化物夹杂逐渐减少,Ti主要以TiN及TiC的形式存在,收得率得到提高;当Al质量分数大于0.033 7%时,Ti的收得率均高于90%;当Al质量分数控制在0.033 7%~0.060 6%时,脱氧效果较好,并可降低夹杂物数量、减小夹杂物的尺寸。     

铝对含钛微合金钢成分控制及夹杂物形成的影响

自主设计了不同Al含量的含钛微合金钢,采用火花源光电直读光谱仪检测了每炉钢的化学成分,分析了Al含量对试验钢中O和Ti含量的影响规律;利用OM、SEM观察了试验钢夹杂物形貌并进行了能谱分析,研究了Al含量对试验钢夹杂物形成的影响规律。研究结果表明：随着Al含量的增加,钢中Ti氧化物夹杂逐渐减少,Ti主要以TiN及TiC的形式存在,收得率得到提高;当Al质量分数大于0.033 7%时,Ti的收得率均高于90%;当Al质量分数控制在0.033 7%~0.060 6%时,脱氧效果较好,并可降低夹杂物数量、减小夹杂物的尺寸。     

Precipitation behavior of MnS on oxide inclusions in Si/Mn deoxidized steel

The precipitation behavior of the MnS phase of MnO-SiO₂ oxides in Si/Mn deoxidized steels was examined. MnS phase formation in the oxide phase was clearly identified, and the Mn content in both phases increased with isothermal holding at 1,200°C. With increased cooling rate, both the size of inclusions and the precipitation ratio of the MnS phase in the oxides decreased. More than 90% of MnO-SiO₂ oxides contain MnS phases and MnS precipitation is accompanied by an Mn-depleted zone around the oxides. This zone was created not just around the MnS, but around the whole oxide inclusion. One can tentatively conclude that the majority of the MnS islands after isothermal holding are formed by the diffusion of Mn and S from the matrix into the inclusions.     

Physical and mathematical modeling of metal flow in the continuous casting of Steel and Aluminum

For a long time it has been recognized that flow of metal in the liquid pool at the head of a continuous caster can have a significant effect on the operability of the caster and the quality of the steel produced. Poorly engineered flows can result in thinning of the shell produced in the mold, with consequent danger of breakouts, entrapment of inclusions or gas bubbles, as well as macrosegregation. There can be similar impacts of the flow in the DC casting of aluminum, Flows are controlled, in the case of steel casting, by the design of the submerged entry nozzle (SEN) and by auxiliary devices sych as electromagnetic brakes and stirrers. In the case of aluminum casting, it is common practice to place a ceramic “bag” around the SEM to control the flow. Usually the design of these devices involves much empiricism; the metal pools arc hot and difficult to access, and flow measurements are therefore difficult. Some use has been made of mathematical and physical models in developing flow control devices. The difficulty with the former is that the flows are turbulent and in a volume with an irregular geometry; consequently, model predictions are questionable unless tested in some way. Such testing can be done using physical models which can also provide their own insights into the nature of the flow. Unfortunately, most physical modeling of casters in the past has been qualitative, or semi-quantitative. The paper describes a project at Berkeley where quantitative results are being obtained from a physical model of a caster with the help of particle image velocimctry (PIV), In this technique (cross correlation PIV), a digital camera records an image of tracer particles scattered throughout the flow. A second image is recorded 33milliseconds later and the two digital images are interrogated by commercial software (Optical Flow Systems. Edinburgh. Scotland) to determine the motion of the particles from one image to the next and yield a vector map of the flow. The technique has been extended to yield time averaged velocity vectors for turbulent flows (the case in the casters and models) by ensemble averaging the vectors from many pairs of images. Water models, including full sized ones, have been constructed for steel and aluminum casters. Various SENs and bags can be used in the model and their effects measured by PIV. Results show that the orientation of the two ports at the bottom of the SEN has a strong effect on the flow in steel casting. The water model of the aluminum caster has shown the strong effect of the bag geometry, and of bag misalignment, on flow in the liquid pool. The commercial software FIDAP has been used to compute time averaged velocities in the physical models. Agreement between measurements and predictions varies from good to fair, depending on conditions.     

连铸含铝钢中Al2O3夹杂物形态控制探讨

水口结瘤是连铸含铝钢面临的主要问题之一。针对连铸含铝钢钢水可浇性问题,首先分析了传统含铝钢中Al2O3夹杂形态控制的钙处理技术。在热力学计算的基础上,提出了高铝钢中夹杂物控制思路,认为采用转炉渣洗和合适的精炼渣而不用钙处理能保证钢水的可浇性。     

铝合金扁锭热顶电磁铸造技术

根据热顶-电磁铸造的基本思想, 设计了一套适合于制取铝合金扁锭的热顶-电磁成型系统, 用小线圈法测量了系统内的磁场强度,计算了电磁压力分布, 并与普通电磁铸造成型系统的结果进行对比分析; 依据热顶电磁铸造的成型条件, 确定了相关的控制参数; 通过大量的拉坯实验, 探讨了热顶对防止电磁铸造坯易产生表面夹杂缺陷的作用。结果表明： 采用热顶-电磁铸造法不仅可有效去除电磁铸造中因电磁搅拌产生的氧化夹杂,而且使得电磁铸造过程简便而易于控制。     

Microstructure and interface reaction of investment casting TiAl alloys

In order to research the microstructure of TiAI alloy and TiAl-mould reaction between TiAI and ceramic mould shells prepared with the low cost binder in investment casting, the ceramic mould shells were prepared with low cost binder and refractory materials. Using two kinds of casting methods （gravity casting and centrifugal casting）, the titanium aluminum alloys with rare earth element （Ti-47.5Al-2Cr-2Nb-0.3Y and Ti-45Al-5Nb-0.3Y） were cast into the mould shells. The microstructures of investment casting titanium aluminum alloys were observed by optical microscope （OM）. The distributions of elements of topping investment on the surfaces of titanium aluminum alloys castings were analyzed by the means of electron probe micro-analysis （EPMA）, and the mechanical properties were studied. The results show that the microstructures of two kinds of titanium aluminum alloys are both lamella shape, and lamella is thin. The thickness of reaction and diffusing layer of Ti-47.5Al-2Cr-2Nb-0.3Y alloy is about 80 μm, and that of Ti-45Al-5Nb-0.3Y is less than 30 μm.     

铸造Ti-47Al-8Cr-2Nb合金的低温超塑性及其组织演变

通过非自耗电弧熔炼及氩气保护浇铸,制备高Cr含量的Ti-47Al-8Cr-2Nb合金。采用金相观察、扫描电镜、透射电镜及高温拉伸测试等实验方法,研究铸态合金在800～1000℃的超塑性变形能力及其变形机制。结果表明,高Cr合金化的铸造Ti-47Al-8Cr-2Nb合金显示出低温超塑性。在850℃的低温及应变速率1&#215;10^-4/s时的最大伸长率为630%,应变速率敏感系数m达到0.51。在800～1000℃的变形激活能为245kJ/mol。合金的低温超塑性变形机制是由晶界扩散控制和β→γ相转变而协调的晶界滑动,β相在变形过程中起到了重要的作用。     

非稳态浇铸条件下IF钢铸坯中大型夹杂物分析

应用了大样电解、扫描电镜、能谱分析等方法,研究了转炉—RH—连铸工序生产IF钢的头坯、交接坯、尾坯中大型夹杂物的质量分数、粒径、来源,并与正常坯进行了对比。结果表明：非稳态浇铸条件下,头坯的大型夹杂物质量分数最高,平均质量分数是正常坯的3.15倍,其次是交接坯和尾坯,平均质量分数均高于正常坯。本次试验只有头坯和尾坯中发现大于300 μm的大型夹杂物,且在头坯中质量分数最高,质量分数为7.47×10－7。交接坯中大于80 μm粒径的夹杂物高于正常坯,而正常坯中则以小于80 μm的夹杂物为主。头坯中大型夹杂物主要来源于结晶器卷渣、耐火材料、中间包渣、引流砂;交接坯和尾坯中大型夹杂物主要来源于结晶器卷渣、中间包渣;正常坯中大型夹杂物的来源主要是水口结瘤以及结晶器卷渣。     

70���������зǽ������������Դ������

 应用光学显微镜和电子探针分析方法,对70钢连铸坯中非金属夹杂物的形貌、大小、数量、组成和来源进行了研究,旨在降低钢中非金属夹杂物的含量,提高钢材质量。结果表明,铸坯中5 μm以上的夹杂物主要为形状不规则的脱硫产物Ⅲ型硫化锰,其次为复合脱氧产物铝硅酸盐和凝固前沿形成的铁氧化物,以及少量脱氧产物与熔蚀耐火材料形成的球状铝酸盐或含镁铝硅酸盐,研究结果为优化70钢连铸坯生产工艺提供了依据。     

钢液脱氧和氧化物夹杂控制的热力学模型

应用多元系亚正规溶液模型计算了CaO—MgO—Al2O3-SiO2和CaO-MnO—Al2O3-SiO2系各组元的活度,并以此为基础建立了钢液脱氧和氧化物夹杂控制的热力学模型,用于炼钢过程脱氧、渣金平衡和氧化物夹杂钢液平衡的热力学计算,以控制钢液脱氧和氧化物夹杂成分．在钢包精炼的渣金平衡条件下钢液硅脱氧和铝硅脱氧后钙处理的工业性实验,以及钢液凝固过程形成的钢中氧化物夹杂分析结果说明,该热力学模拟方法可用于钢包精炼中钢液的脱氧控制和钢中氧化物夹杂控制．     

脱氧铝对铸件力学性能的影响

通过对精铸件中脱氧铝加入量进行试验,分析了脱氧铝加入量对铸件冲击吸收能量的影响,提出了脱氧铝的较佳加入量,提供了判断精铸件脆性断裂形成原因的试验方法。     

转炉生产低合金钢的纯净度

结合济钢转炉的生产实践，分析了低合金钢中夹杂物的来源、形状、大小和分布规律，提出了改进连铸坯内部质量的措施，为开发生产纯净钢提供了依据。     

外加颗粒增强钢基复合材料的研究

采用离心铸造法获得了WC颗粒增强钢基复合材料环形件，其复合层厚度为15～18mm。分析表明：复合材料层的组织由大量的骨状的复式碳化物和针状马氏体基体组成；复合材料层中增强颗粒被高温钢液全部溶化，原位析出含W，Fe，Cr，Mo复式碳化物；基体合金被溶解的增强颗粒不同程度的合金化，复合层从外至内韧性升高、硬度降低，但梯度不大。     

Morphology and chemistry of oxide inclusions after Al and Ti complex deoxidation

The morphology and chemistry of oxide inclusions after various Al and Ti complex deoxidation sequences were investigated at 1600°C. Depending on the addition sequence of Al and Ti deoxidants and the holding time, the morphology and the chemistry were changed. In particular, when Ti was added prior to Al, spherical Al₂O₃ oxide inclusions with hollow holes were frequently observed, which is reported for the first time. On the other hand, when Al was added prior to Ti, Al₂O₃ inclusion formed. When Al and Ti were added simultaneously, Al−Ti−O oxide inclusion formed in the beginning and was transformed to Al₂O₃ inclusion. Based on the experimental results, the formation mechanism of the oxide inclusions after Al−Ti deoxidation was proposed. The nozzle clogging of Ti bearing Al killed steel was also discussed based on the experimental results.     

颗粒增强铝基复合材料铸造方法评述与实践

颗粒增强铝基复合材料具有十分广阔的应用前景,用铸造法制取是把这种材料推向工业规模应用的有效手段。对几种主要的铸造复合方法进行了评述,认为半固态搅拌法最简单、可靠和经济。还介绍了作者应用此法进行的实践。