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因铸铁基体结构疏松、多孔,直接镀Ni-Fe合金其工艺控制的难度比较大。为此,本文着重论述了铸铁基体上镀光亮Ni-Fe合金的工艺要求、镀液配方及镀层性能。 相似文献
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叙述了铸铁车间树脂砂造型和旧砂再生线的工艺及设备设计要点、生产组织,并对树脂砂工艺和粘土砂工艺的铸件质量和生产成本进行比较。 相似文献
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在对铸铁焊补工艺进行分析的基础上,结合焊接生产实际,进行了模拟焊接工艺试验,最后用E5016焊条外缠绕铜丝对C6140机床油槽(材质HT250)底部出现的漏油缺陷进行了焊补,解决了铸铁焊接中易出现白口及裂纹等问题,获得了良好的焊缝,取得了满意的效果.此方法操作方便、易行,改善了劳动条件,降低了生产成本,为铸铁焊补提供了有效的途径. 相似文献
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This article addresses the effect of cooling rate on microstructure and mechanical properties as determined by changing molding media and section size. The research was conducted for thin-walled iron castings with 2-5-mm wall thickness and for the reference casting with 13-mm wall thickness, using different molding materials (silica sand and insulating sand “LDASC”) to achieve various cooling rates. Thermal analysis was performed to determine the real cooling rate at the beginning of the graphite eutectic solidification. In general, it was found that the predictions based on theoretical analysis of the solidification process of ductile iron are in good agreement with the experimental outcomes. Finally, the present study provides insights into the effect of cooling rate on the graphite nodule count, the ferrite fraction and mechanical properties of thin-walled ductile iron castings. The study shows that the cooling rate of thin-walled castings varies in a wide range (80-15 °C/s) when changing the wall thickness from 2 to 5 mm, accompanied by significantly changing the mechanical properties of ductile iron. The cooling rate can be effectively reduced by applying an insulating sand to obtain the desired properties of thin-walled castings practically in the whole range of ductile iron grades in accordance with the ASTM Standard. 相似文献
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《中国铸造》2015,(6)
To develop materials suitable for spent-nuclear-fuel containers, the effect of forced cooling on mechanical properties and fracture toughness of heavy section ductile iron was investigated. Two cubic castings with different cooling processes were prepared: casting A was prepared in a totally sand mold, and casting B was prepared in a sand mold with two chilling blocks placed on the left and right sides of the mold. Three positions in each casting with different solidification cooling rates were chosen. In-situ SEM tensile experiment was used to observe the dynamic tensile process. Fracture analysis was conducted to study the influence of vermicular and slightly irregular spheroidal graphite on the fracture behavior of heavy section ductile iron. Results show that the tensile strength, elongation, impact toughness and fracture toughness at different positions of the two castings all decrease with decreasing cooling rate. With the increase of solidification time, the fracture mechanism of conventional casting A changes from ductile fracture to brittle fracture, and that of casting B with forced cooling changes from ductile fracture to a mixture of ductile-brittle fracture. 相似文献
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采用垂直上引连续铸造技术对QT500-7进行铸铁管成型,对该铸件采用不同温度与时间的等温淬火,并进行微观组织与力学性能分析测试。结果表明,用该技术生产的铸件与普通砂型铸造的铸件相比较,不仅球化率高而且球化均匀,经过不同等温淬火后其抗拉强度和冲击韧度值明显升高,非常适合制作汽车发动机缸套和活塞环以及其他的铸铁空心零件。 相似文献
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R. Dańko M. Holtzer M. Górny S. Żymankowska-Kumon 《Journal of Materials Engineering and Performance》2013,22(11):3592-3600
The paper presents the results of investigations of the influence of the quality of molding sand with furan resin hardened by paratoluenesulfonic acid, on the formation of microstructure and surface quality of ductile iron castings. Within the studies different molding sands were used: molding sand prepared with fresh sand and molding sands prepared with reclaimed sands of a different purification degree, determined by the ignition loss value. Various concentrations of sulfur and nitrogen in the sand molds as a function of the ignition loss were shown in the paper. A series of experimental melts of ductile iron in molds made of molding sand characterized by different levels of surface-active elements (e.g., sulfur) and different gas evolution rates were performed. It was shown that there exists a significant effect of the quality of the sand on the formation of the graphite degeneration layer. 相似文献
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论述了以覆膜砂离心铸造和用含锰及微量元素含量较高的再生铁进行球化处理浇注球铁管的方法,研究了模内孕育,随流孕育和金属铋孕育对铸态球铁管塑性的影响,考察了锰,硅和碳当量及衬砂层厚度对铸态球铁管塑性的影响规律。 相似文献
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The influence of the use of moulding sand with furan resin, prepared both with fresh sand and reclaimed matrix, on the formation of a flake graphite formation at the surface layer of ductile iron castings has been investigated. A series of experimental heats of ductile iron cast in moulds made of moulding sand characterised by different levels of surface active elements (sulphur, oxygen) were performed. The effect of the wall thickness and the initial temperature of the metal in the mould cavity on the formation of flake graphite in the surface layer of the casting is shown in the paper. Investigations carried out by means of scanning electron microscopy (energy dispersive X-ray spectroscopy and wavelength dispersive X-ray spectroscopy) showed concentration of gradient profiles of surface active elements in the castings surface layer, which are responsible for their quality. Finally, it has been shown that there exists a significant effect of the quality of the sand on the formation of the flake graphite layer and the surface characteristics of ductile iron castings. 相似文献
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Pierre-Marie Geffroy Merouane Lakehal Javier Goñi Eric Beaugnon Jean-François Silvain 《Journal of Materials Processing Technology》2009,209(8):4103-4111
The magnetic molding process is an extension of lost foam process and uses an expendable pattern surrounded by steel shot bonded together by the action of an induced magnetic field. This paper presents the comparative results obtained from sand mold and magnetic molding processes for grey cast iron and ductile iron castings. Therefore, this paper reviews the factors involved in the production of suitable patterns and the magnetic mold and on the other hand presents the comparative microstructures obtained for grey cast iron and ductile iron castings. This study also describes the advantages and the characteristics of the magnetic molding process. The main factors involved in the magnetic molding process are also discussed. 相似文献
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论述了在用湿型砂生产铸铁件的型砂系统中混入大量树脂砂时,对型砂粒度、膨润土有效含量、抗粘砂性能的影响,并提出了相应的措施.针对铸造一厂的型砂系统,详细介绍了灰铸铁型砂系统物料的变化情况、混入树脂砂对型砂发气量的影响,并成功实施了将灰铸铁型砂系统的旧砂代替新砂使用在球墨铸铁型砂中的工艺,这一工艺的实施不仅降低了成本和铸件缺陷,而且使型砂的性能更稳定.实践证明:在用湿型砂生产有芯铸件时,芯砂的粒度要与型砂的粒度基本一致;混入树脂砂中的树脂膜可以起到一定的防止铸铁件粘砂作用,应当加以利用;适当地往型砂系统中补充旧砂对型砂系统的稳定是有利的;控制好型砂的有效膨润土含量和有效添加剂含量是大量树脂砂混入型砂系统情况下稳定型砂系统的有效途径. 相似文献
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根据钛合金成形模具的技术要求,研制了一种高温力学性能较好的中硅锰钼球铁模具材料。通过选择合适的化学成分,适当提高锰的含量,并采用合理的孕育和热处理工艺,所获得的中硅锰钼球铁高温硬度比中硅钼球铁提高33%。采用酯硬化水玻璃砂消失模铸造工艺制造的钛合金成形模具,能满足600~800℃下成形的技术要求。 相似文献