Cerium Distribution in Spheroidal Graphite of Cast Iron

Six thin sections of spheroidal graphites in cast iron have been investigated by TEM and SEM.Thespheroidal graphites consist of two or three layers and have nuclei which are composed of Ce_2O_2S and Ce_2O_3.Cerium is existed ont only in nuclei,but also in central layer and middle layer of graphite.     

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.     

Wear Behavior and Mechanism of Spheroidal Graphite Cast Iron

Wear behavior and mechanism of spheroidal graphite cast iron were studied on a pin-on-disk elevated temperature wear tester. The phase and morphology of worn surfaces were examined by X-ray diffraction and scanning electron microscopy. Results show that with an increase of load, wear rate of spheroidal graphite cast iron gradually increases under low loads, rapidly increases or potentially increases under high loads; wear rate increases with increasing ambient temperature. At 25–200 °C, adhesive wear prevails; oxidative wear and adhesive wear coexist at 100 °C. As load surpasses 150 N at 100 °C, extrusive wear appears. The elevated-temperature wear of spheroidal graphite cast iron is a physical and chemical process including the following reactions: xFe + y/2O₂?Fe_xO_y, 2C + O₂?2CO and Fe_xOy + yCO?xFe+yCO₂. Hence, at 400 °C, the amount of graphite and tribo-oxides are substantially reduced because of reductive function of graphite. It can be suggested that wear-reduced effect of graphite and tribo-oxides is impaired.     

稀土对球墨铸铁中共存As、Sn、Pb、Ti的中和作用

全部采用龙岩生铁，制取球墨铸铁。球化剂为镁硅铁合金，同时分别添加０．００％、０．０１％、０．０２％、０．０３％、０．０４％、０．０５％、０．０７％稀土硅铁合金进行球化处理。结果表明，稀土不能完全消除与中和高含量微量元素共存对石墨球化的干扰作用。但适量稀土可部分中和微量元素、促进形核、改善球状石墨的表面形貌。削弱微量元素的有害作用。     

稀土对高Ni-Cr铸铁石墨的变质作用

采用金相和电镜等手段对稀土在高Ｎｉ－Ｃｒ铸铁中的行为进行了研究。结果表明：稀土可以改善高Ｎｉ－Ｃｒ铸铁石墨的形态及分布，使之由长条状向短厚状过渡。并且随着稀土加入量增多，石墨数量增加。     

球墨铸铁液压件发热冒口的研究

耐高压的液压件采用球墨铸铁（简称“球铁”）材质是一项先进技术。但是球铁的补缩困难,特别是对薄壁、复杂的液压件,热节处易产生缩松而导致铸件的渗漏,这是采用球铁生产液压件的关键问题。我们采用发热冒口解决球铁液压件的补缩问题。研究结果表明:发热冒口套热损失率比普通砂型冒口降低53%,等效模数约为几何模数（砂型冒口的模数）的两倍。节约冒口金属的50～80%,解决了普通砂型冒口解决不了的球铁液压件的补缩问题。     

铸铁中石墨形成机理的再探讨

运用金属型人实验仪证实，进行冷却的铸造铁水内部存在着温差电势场，且为点电势场，其寿命约为０．０５～３．５８ｓ。我们发现，这种电势场是运动的，运动速率与其所的区域的温度梯度的变化率有关，分析并找出了决定铸铁中石墨形态的关键因素。     

稀土耐热蠕墨铸铁的试验研究

采用稀土为主的含低沸点元素的蠕化剂生产了耐热蠕墨铸铁。研究了稀土耐热蠕墨铸铁的抗氧化、抗生长及热疲劳性能。结果表明，所研制的稀土耐热蠕墨铸铁具有优良的耐热性能     

The Microstructure of Graphite Spherulites in Cast Iron

The microstructure of graphite spherulites （G.S.） in Ce addition ductile cast iron was carried out using transmission electron microscopy （TEM） techniques. The structral characterization of the graphites is as following: there are platelets growing along the periphery as well as fan-like structure formed from platelet aggregates in the diameter section of spherulite, in which most of the platelets are with sizes ranging from several to tens nm in radial; the [001] direction of the platelets would have a tend to parallel to radial of the G. S. and meanwhile, they also a small misorientation deviated from the radial among the platelets each other. It shows that the anisotropy of graphites has been restrained by adding Ce element in cast iron and the structural characterization of the G. S. is consistent with the Double’ s model of the conical helixes formed in helical growing and branching.     

稀土奥-贝蠕铁性能随温度的变化

用万能电子材料试验机等设备，研究了稀土奥—贝蠕铁在高温下的冲击、热疲劳、氧化质量增量、伸长率以及室温硬度等。通过这些高温性能的研究，揭示了稀土奥—贝蠕铁在高温下工作的条件与范围。     

稀土变质铸铁石墨形态的转变

采用定向凝固实验方法考察了低凝固速度（下限为０．５ｍｍ／ｈ）下稀土变质铸铁石墨形态的转变。结果表明,随着稀土含量的增加,石墨形态呈现由Ａ型片状→Ａ′型片状→珊瑚状→蠕虫状→球状→开花状的一系列转变;石墨形态由片状到非片状的转变是由于生长方式改变所致,而这种改变取决于稀土含量,与凝固速度（或冷却速度）无关;石墨单体可以发生片状与非片状之间的连续转变,但在试样宏观的片状石墨区域与非片状石墨区域之间却存在着明显的分界线,说明石墨生长方式在试样宏观区域间发生了突变。     

Effect of RE Complex Inoculation on the Fatigue Wear Behaviours of High Chromium Cast Iron

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球墨铸铁微观组织形成的数值模拟

基于结晶动力学理论,建立了球墨铸铁凝固过程各阶段微观组织形成形核和长大的数学模型;根据该结晶动力学模型,编制了球铁微观组织形成模拟软件FTStructure．该软件可以预测球铁凝固过程中各相的形成以及固态转变中铁素体和珠光体的形成,并进而预测铸态力学性能．模拟了阶梯形试块的冷却曲线、微观组织和布氏硬度．模拟与实测结果符合较好．     

稀土铸铁中蠕虫状石墨空间组织的基本形态

采用定向凝固方法研究了蠕虫状石墨空间组织的基本形态。结果表明,蠕墨的主杆部分是一个以棱柱为基础且在其四周有花瓣形或星影分叉的复合柱体。由偏光金相显微镜对蠕墨主杆横截面的分析并结合透射电镜的分析结果,对蠕墨在偏振光下不时出现的\     

球墨铸管退火炉设备的改进

对球墨铸管退火炉加热段改造,采用平焰烧嘴和两区控温,降低了炉膛高度并采用耐火纤维模块替代浇注料,使温度调节灵活,提高了产品质量和降低能耗。     

稀土在离心灰铸铁管中的作用

利用光学显微镜和扫描电镜并结合电子探针和化学分析,研究了稀土在离心灰铸铁管中的作用。结果表明,在保证灰口铸铁的先决条件下,普通离心灰铸铁管的组织,尽管可随基本化学成分和铸造条件的不同而变化,但其特征是组织粗大且很不均匀,并有明显的分层现象。加入微量稀土后,无论显微组织和宏观组织都显著趋于细化和均匀化,同时,化学成分的偏析也有明显改善。     

蠕墨铸铁在焦炉护炉铁件设计中的应用

蠕墨铸铁具有较高的机械性能和良好的抗热疲劳、耐磨损、耐热腐蚀的性能。采用蠕墨铸铁代替灰铸铁作护炉铁件材料 ,经对炉门、炉框、大保护板强度进行核算 ,证明蠕墨铸铁适合于护炉铁件 ,并具有可观的经济效益     

Fracture Characteristics of Austempered Spheroidal Graphite Aluminum Cast Irons

The fracture characteristics of austempered spheroidal graphite aluminum cast iron had been investigated. The chemical content of the alloy was C 3.2, Al 2.2, Ni 0.8 and Mg 0.05 (in mass percent, %). Impact test samples were produced from keel blocks cast in CO2 molding process. The oversized impact samples were austenitized at 850 and 950 ℃ for 2 h followed by austempering at 300 and 400 ℃ for 30, 60, 120 and 180 min. The austempered samples were machined and tested at room temperature. The impact strength values for those samples austempered at 400 ℃ varied between 90 and 110 J. Lower bainitic structures showed impact strength values of 22 to 50 J. The fractures of the samples were examined using SEM. The results showed that the upper bainitic fracture revealed a honey Comb-like topography, which confirmed the ductile fracture behavior. The lower bainitic fractures of those samples austempered for short times revealed brittle fracture.     

含砷锡铅钛球铁原铁水含硫量对稀土合适加入量的影响

研究了球墨铸铁原铁水中共存的砷、锡、铅、钛等微量元素含量相同时硫含量对稀土合适加入量的影响,以及孕育剂和孕育方式对石墨球化和力学性能的影响。结果表明,原铁水硫含量不同的球墨铸铁,最佳的稀土加入量均为0.005%左右,但原铁水硫含量增加,稀土合适加入量的范围减小;硫加剧微量元素对力学性能的有害影响,稀土不能完全中和与消除硫对力学性能的危害作用;强化孕育是削弱微量元素有害作用、提高力学性能的有效措施。     

蠕墨铸铁生产工艺控制

以Z14号生铁为原料,用中频炉熔炼原铁液,加入1.1%的FeSiMg4Re17作为蠕化剂,1%的FeSi75作为孕育剂,采用平底包冲入法蠕化处理原铁液,控制出铁温度为1420～1450℃,待反应结束后在10min内浇注完毕,可获得合格的蠕墨铸铁工件.检测表明,所生产的铸件成分稳定,石墨蠕化率为62%,机械性能达到国家标准.