Stable Eutectoid Transformation in Nodular Cast Iron: Modeling and Validation

This paper presents a new microstructural model of the stable eutectoid transformation in a spheroidal cast iron. The model takes into account the nucleation and growth of ferrite grains and the growth of graphite spheroids. Different laws are assumed for the growth of both phases during and below the intercritical stable eutectoid. At a microstructural level, the initial conditions for the phase transformations are obtained from the microstructural simulation of solidification of the material, which considers the divorced eutectic and the subsequent growth of graphite spheroids up to the initiation of the stable eutectoid transformation. The temperature field is obtained by solving the energy equation by means of finite elements. The microstructural (phase change) and macrostructural (energy balance) models are coupled by a sequential multiscale procedure. Experimental validation of the model is achieved by comparison with measured values of fractions and radius of 2D view of ferrite grains. Agreement with such experiments indicates that the present model is capable of predicting ferrite phase fraction and grain size with reasonable accuracy.     

球墨铸铁金相图片分析系统

为了解决传统金相定量分析法准确性差、运算速度慢的缺点,用计算机图像处理技术实现了球墨铸铁金相图片的定量分析,很好地满足了生产中对球墨铸铁金相分析的要求。     

喷粉在水冷金属型离心球墨铸铁管中的应用

为了消除水冷金属型离心球墨铸铁管的重皮、冷隔、气孔等铸造缺陷,降低管模的机械磨损及热疲劳,采用了向管横内喷撒SiBa-13合金粉的方法。经合理控制用量和喷撒工艺,消除了铸管气孔、重皮等缺陷,改善了冷却顺序,降低了热疲劳,提高了管模的使用寿命。     

合金元素对奥氏体-贝氏体型球墨铸铁组织和性能的影响

根据不同的合金元素对球墨铸铁基体组织的影响，将锰、钼、镍和铜的含量合理搭配，以岩棉为冷却介质，在连续冷却过程中获得了性能较好的奥氏体-贝氏体型球墨铸铁，HRC可达33～48，αk可达26～48J／cm^2。     

Microstructure and Mechanical Properties of Nodular Cast Iron Produced by Melted Metal Die Forging Process

 The microstructure and mechanical properties of nodular cast iron produced by the melted metal die forging process (MMDF for short) were experimentally researched. The main obtained results are: the nodular cast iron produced by this process can be machined as easy as traditional one only if holding at the remained temperature for 4 h; its strength and plasticity are obviously higher than those of traditional ones; the graphite size arrived at grade 8, and the graphite spheroidizing arrived at grade 1 or 2, but a streamline molded distribution of the graphite slightly appeared. Both of the strength and plasticity increased with the pressure when the pressure holding time was larger than its critical value. A new way to produce high properties nodular cast iron was provided.     

Solidification of SiMo Nodular Cast Iron for High Temperature Applications

During the 1960s and 70s research was aimed at developing a material withstanding the ever higher temperatures in a combustion engine. This work resulted in what have later been named SiMo and D5S. SiMo is a nodular cast iron typically containing 4?C6?% Si and 0.5?C2?% Mo and can be used in temperatures up to 850?C860?°C. D5S is a nickel base material. High silicon and silicon?Cmolybdenum content improves the dimensional stability of ductile iron. Silicon increases the transformation temperature where austenite transforms to ferrite. Molybdenum partly segregates and freezes in intercellular regions, promoting carbides while during the solid state transformation molybdenum particles precipitate around grain boundaries. The solidified material shows a range of interesting structures and phases which will be presented.     

Production of Hot-Worked Bars and Tubes of Nodular Cast Iron

Results are presented from the experimental production of nodular cast iron by the hot extrusion of bars and tubes with the largest possible elongation. It is established that semifinished products made of nodular cast iron can be subjected to piercing and helical rolling.     

钒钛球墨铸铁齿轮的弯曲静强度

通过试验,得到具有铁素体和贝氏体双相组织的钒钛球铁齿轮的弯曲静强度计算公式。进一步证明了,轮齿的塑性变形量与齿根应力的关系式。该试验数据,进一步充实和扩展了球铁齿轮的σ₁和k值。     

镍钼球墨铸铁轧辊生产实践

用理论与实践相结合的方法，进行镍钼球墨铸铁轧辊开发试制，在相对装备水平不高的情况下，原四川长城特殊钢集团公司机电建设有限公司，生产出完全达到国家标准的镍钼球墨铸铁轧辊，投入试用后，反映情况良好。     

稀土球墨铸铁曲轴断裂的分析

运用线弹性断裂力学理论研究柴油机稀土球墨铸铁曲轴断裂强度和寿命问题。曲轴断裂的主要原因在于曲柄臂与连杆轴颈过渡圆角处存在缺陷,这个位置的缺陷在疲劳扩展达到临界状态时便导致曲轴失稳断裂。根据断裂力学理论和实验分析,提出了降低断裂率的一些途径。     

Improvements in the Characteristics of Nodular Graphite Cast Iron for Crankshafts

This study deals with spheroidal graphite cast iron metallurgy for the mass production of engine crankshafts. Pieces have been made in three different grades under industrial conditions. CCT diagrams and micrographs show that it is possible to remove the undesirable “bull's eye” ferrite from the matrix as well as to improve the mechanical properties of series parts by only altering the chemical composition. A 100% pearlitic matrix and up to a 14% increase in the tensile strength have been obtained by lowering the amount of silicon and increasing the share of pearlitizing elements such as copper and manganese without altering the cooling speed of the parts. The effect of the cooling speed on the matrix microstructure and the mechanical features has also been revealed. For an “improved” grade, the matrix is 100% pearlitic, its hardness is about 390Hv30kg for a cooling speed of around 150°C/min.     

高炉用铸铁铸钢冷却壁设计与制造

着重介绍高炉铸铁、铸钢冷却壁的材质选择和制造要点。通过对冷却壁使用工况的分析,阐述了冷却壁材质选择和结构设计的原则。通过冷却壁材质、制造工艺、时效处理等环节的控制,稳定并提高了铸铁、铸钢冷却壁的使用寿命,实现了冷却壁综合质量指标,从而为实现高炉长寿的最终目的创造了条件。     

合金球墨铸铁基体组织对含镍球墨铸铁热疲劳性能的影响

将同炉熔炼并同时浇铸的 ,镍约 0 .7%的合金球墨铸铁楔形试块粗加工后热处理成 6种基体组织 ,再精加工成 2 0 m m× 2 0 m m圆柱试样。对试样进行了 (6 0 0± 10 )℃ (盐浴 )～ (70± 30 )℃(油 )和 (6 5 0± 10 )℃ (盐浴 )～ (2 5± 5 )℃ (水 )两种冷热循环试验 ,得到了一致的结果。发现 ,不同基体的试样其抗热疲劳性能由高到低依次为 :下贝氏体基体→ 5 6 0℃回火调质基体→ 5 80℃回火调质基体→ 6 0 0℃回火调质基体→正火片状珠光体基体→奥 -贝基体。作者结合不同基体组织的硬度和强度以及 Ac1 点以下温度范围内上述各种基体组织的热力学稳定性等因素对热疲劳性能的影响 ,阐明了导致上述试验结果的原因。     

激光处理球墨铸铁轧辊提高其使用寿命的实践

介绍了激光处理轧辊提高使用寿命的原理,阐述了激光处理轧辊的试验效果,获得了良好的经济效益。     

PIXE分析技术在球墨铸铁元素微分析中的应用

本文针对常规测量方法测量球铁石墨相中反球化元素含量的局限性和灵敏度低等问题,提出用电解分离工艺提取石墨相,制成无内标和含内际厚靶,用PIXE分析技术测量反球化元素和杂质元素的含量,与电子微探针相比测量下限可以提高三个量级。     

Centrifugal Casting of High Speed Steel/Nodular Cast Iron Compound Roll Collar

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Effects of Light and Heavy Rare Earths on Anti-Degradation of Nodular Cast Iron

The effects of rare earths with different contents on anti-degradation of Y base heavy rare earths-magnesium and cerium base light rare earths-magnesium nodular cast iron were studied. Curves of the relationship between the spheroidization grade of liguid iron treated by different nodulizers and holding time were obtained. The results show that the more the remains of the rare earth, the longer the anti-degradation time, the liquid iron was treated either by Y-Mg-Si or by Ce-Mg-Si nodulizer. When the rare earth remains are above certain quantity, the spheroidization grade starts to decline. When liquid iron treated by either Y-Mg-Si or Ce-Mg-Si nodulizer with proper remains of rare earths about 0.04% 0.06%（mass fraction）, the anti-degradation is the best, and the remains of Mg being about 0.04% -0.07% （mass fraction）. Rare earths-Mg nodulizer with moderate RE remains is better than that of Mg-Si nodulizer in anti-degradation property. However, Y-Mg-Si nodulizer with moderate remins of Re is better than Ce-Mg-Si nodulizer. Sometimes Ce-Mg- Si nodulizer can be used for the production of heavy section nodular cast iron.     

Modeling of Cast Iron Solidification—The Defining Moments

There are many to contend that today human civilization has reached the age of engineered materials, yet the importance of iron castings continues to support the thesis that we are still in the Iron Age. Cast iron, the .rst man-made composite, is at least 2500 years old. It remains the most important casting material, with about 75 pct of the total world tonnage. This article is a review of the mathematical models that describe the fundamentals of solidification of iron-base materials, from the seminal articles by Jackson–Hunt (JH) and that of Old.eld, the first to attempt modeling of microstructure evolution during solidification, to the prediction of mechanical properties. The latest analytical models for irregular eutectics such as cast iron as well as numerical models with microstructure output (visualization models) are discussed. Because of space limitations, models for casting soundness are not included. This article is based on a presentation made in the symposium entitled “solidification Modeling and Microstructure Formation: In Honor of Prof. John Hunt,” which occurred March 13–15, 2006, during the TMS Spring Meeting in San Antonio, Texas, under the auspices of the TMS Materials Processing and Manufacturing Division, Solidification Committee.     

球墨铸铁件机体铸造工艺研究与生产实践

对球墨铸铁件机体的铸造工艺和施工难点作了详尽总结，实用性强，对铸造专业技术人员解决类似问题，拓宽思路，编制铸造工艺和生产施工都具有很好的借鉴作用，有些地方可直接引用，指导生产。