稀土球铁中Ce的分布及作用

用定向凝固和电解萃取—放射性同位素测量技术,分析了球化剂Ce在球铁各相中的分布;配合测量石墨球化率,确定了球铁含Ce量与石墨球化程度的关系,结果表明:Ce在球铁中主要以合金化Ce的形式存在,但石墨相Ce含量是石墨球化程度的表征值;只有当石墨相Ce含量高于一定值时,石墨才能完全球化。     

MICRODISTRIBUTION OF NODULIZER IN VARIOUS PHASES OF CAST IRON

应用有机电解液低温电解及放射性测量方法,测定了普通铸铁及高纯Fe-C-Si合金中的合金化Ce量及石墨中的Ce量,石墨中的Ce量大都略高于或相近于基体中的Ce量,在Ce含量相同的情况下,铸铁中的合金化Ce量比钢中多。 涂层法自射线照相结果表明:Ce在片状石墨中呈均匀分布,而在球状石墨中的分布却是多样的。开花状石墨中的Ce多于片状石墨及球状石墨中的Ce.球状石墨周围的铁素体及珠光体是贫Ce.远离球状石墨的珠光体及莱氏体是富Ce.初生奥氏体枝晶转变形成的珠光体和蜂窝状莱氏体都含有较少的Ce,而板状渗碳体型莱氏体含Ce较多.Ce明显富集于共晶时最后凝固的区域。球状石墨的形成主要取决于原铁水中的反球化剂(硫)含量,它的影响比球化剂的残留量或合金化量的作用更大。     

确保大断面球墨铸铁件质量的措施

采用冲天炉熔化,中频炉内脱硫和升温,采用稀土镁做球化剂,进行多次孕育处理并加入微量锑,能防止大断面球铁件发生球化衰退、石墨畸变和球数减少等缺陷。     

钇基重REMg球化剂在风电铸件中的应用

介绍了QT400-18AL的主箱体和QT450-10的3 MW行星架铸件的要求和铸造工艺,以及生产厚大球铁铸件必须重视的问题,试验结果显示:应用Y基重REMg球化剂生产大断面风电球铁铸件,具有较强的抗球化衰退能力,铸件的各项力学性能指标完全符合材料要求。分析Y基重REMg球化剂抗球化衰退的原因为:①重RE元素沸点高;②不会发生因返S现象而导致的球化衰退;③具有较强的抗石墨畸变能力;④充分利用了RE元素间和Mg、Ba、Ca之间互为补充的叠加作用及复合作用。     

防止大断面球铁石墨畸变的工艺措施

采用大断面球铁模拟方法，试验和分析了球化剂，悬浮浇注和微量元素对大断面球铁石墨组织的影响。试验结果表明：运用混合球化剂，悬浮浇注工艺和加入微量元素Sn,Sb，可以防止组织中的石墨畸变，细化石墨球和提高球化级别。     

蠕墨铸铁生产新工艺试验

以球铁衰退过程中蠕墨存在时间较长为依据,提出通过变质将球铁铁水瞬时变为蠕铁的蠕墨铸铁生产工艺,并通过试验制成LS型瞬时蠕化剂,为稳定灵活生产蠕墨铸铁找到一种新工艺。     

大断面球铁混合球化剂试验研究

在模拟大断面球铁试验条件下，研究了低硅镁团块、稀土镁硅合金及混合球化剂对大断面球铁石墨形态的影响。试验结果表明，７０％低硅镁团块＋３０％稀土镁硅合金混合球化剂可提高大断面球铁球化级别和改善石墨形态。     

直缝焊管轧机轧辊球铁材质研究

研究了轧辊新材质———铜钒钛球铁。对石墨球化、铸态基体组织、力学性能、淬硬性、淬透性和滚、滑动摩擦磨损特性的系统研究表明，合金铜钒钛球铁是一种价格低廉、淬透性、耐磨性比ＧＣｒ１５钢更好的轧辊材质，更适合替代ＧＣｒ１５钢材质制造中、小截面轧辊     

铁液预处理在球墨铸铁和灰铸铁生产中的应用

分析了感应电炉熔炼铁液石墨结晶核心减少的原因,说明石墨结晶核心减少会增大灰铸铁和球墨铸铁件的缩孔、缩松倾向,降低铸件的力学性能.指出预处理的主要作用是增加铁液的石墨结晶核心,改善球化处理和孕育处理的效果.叙述了常见预处理剂的特点,详细介绍了SiC预处理的具体操作要点,主要是:炉内铁液成分和温度合适时,扒渣,加入预处理剂...     

球墨铸铁预处理技术原理及生产应用实例

介绍了预处理技术提高球铁冶金质量(包括细化石墨球、增加石墨球数、提高球化率、改善铁液流动性和降低球铁件缩松、缩孔倾向)的基本原理;强调了其应用要点在于预处理反应Ba+O→BaO、Ba+S→BaS、La+S→LaS须在球化反应前进行,才能达到为铁液球化提供良好基础的目的;用高质量厚大球铁件和薄壁球铁件的生产实例说明了预处理技术的优势所在。     

Mn和Ce对Fe-Ni-Mn-C-Si-Ce系合金组织和性能的影响

采用熔炼法制备出新型高耐磨的Fe-20Ni-xMn-3.5C-2.5Si系固体自润滑材料,研究稀土元素Ce对Fe-20Ni-xMn-3.5C-2.5Si系合金中石墨的球化作用及Mn含量对力学性能及摩擦磨损性能的影响。结果表明：随着Mn含量的增加,合金凝固组织中奥氏体的硬度逐渐增大,特别是Fe-20Ni-xMn-3.5C-2.5Si-0.75Ce系合金在摩擦过程中的表面硬度大幅度提高,呈现出高锰钢特有的表面加工硬化性质,通过TEM可以观察到磨损表面生成孪晶型马氏体;添加0.75%（质量分数）的稀土Ce可以使结晶的石墨球化,使抗拉强度和抗弯强度大幅度提高,大约比未经球化处理的提高3～5.8倍;稀土Ce的加入可以促进Fe1.1Mn3.9C2型碳化物的生成,使材料的耐磨性进一步提高,其中Fe-20Ni-16Mn-3.5C-2.5Si-0.75Ce合金的磨损率最低,大约是QT500球墨铸铁的1/13。     

Microstructures and wear properties of graphite and Al2O3 reinforced AZ91D-Cex composites

The magnesium matrix composites reinforced by graphite particles and Al2O3 short fibers were fabricated by squeeze-infiltration technique. The additions dispersed uniformly and no agglomeration and casting defect were observed. The microstructures and wear properties of the composites with different Ce contents of 0, 0.4%, 0.8% and 1.0%, respectively, were investigated. Especially, the effect of Ce on the properties was discussed. The results reveal that Ce enriches around the boundaries of graphite particles and forms Al3Ce phase with Al. The addition of Ce refines the microstructures of the composites. With the increase of Ce content, the grain size becomes smaller and the wear resistance of the composite is improved. At low load, the composites have similar worn surface. At high load, the composite with 1.0% Ce has the best wear resistance due to the existence of Al3Ce phase. The Al3Ce phase improves the thermal stability of the matrix so the graphite particles can keep intact, which can still work as lubricant. At low load, the wear mechanism is abrasive wear and oxidation wear. At high load, the wear mechanism changes to delamination wear for all the composites.     

Distribution of some active elements in primary graphite precipitates

The distributions of cerium and oxygen in the matrix and in graphite precipitates of a pure Fe–C–Ce cast iron sample have been studied using scanning Auger microscopy. It is shown that there is no accumulation of any element at the graphite-matrix interface. Cerium was detected in some cases in spheroidal graphite precipitates, most often associated with oxygen. Various non-spheroidal graphite precipitates proved to contain cerium and oxygen suggesting a correlation between cerium content and graphite degeneracy.     

Effect of graphite content on wear property of graphite/Al_2O_3/Mg-9Al-1Zn-0.8Ce composites

Using squeeze-infiltration technique, Mg-9Al-1Zn-0.8Ce composite reinforced by graphite particles and Al2O3 short fibers was fabricated. The reinforcing phases combined closely with the matrix and no agglomeration was observed. The microstructure, hardness and wear property of the composites with the graphite content of 5%, 10%, 15% and 20% were investigated, respectively. The results reveal that Ce tends to enrich around the boundaries of graphite particles and Al2O3 short fibers, and forms Al3Ce phase. Wh...     

6.0MW风力发电机球铁底座铸件的生产

利用2台20 t中频电炉熔炼铁液,生产质量为60 t的6.0 MW超大型风力发电机球铁底座铸件.采用底注式浇注系统,厚大部位设置冷铁,顶部设置冷冒口,低温快速浇注.通过严格控制化学成分和出炉温度,合理设计熔化工艺及球化处理、孕育处理流程,尽量缩短铁液停留时间,解决了小容量电炉生产超大型厚壁球墨铸铁件容易导致球化衰退和石墨畸变的难题.     

DN80水冷离心球墨铸铁管生产工艺及缺陷防止措施

对DN80离心球墨铸管关键工艺如熔炼、球化、离心浇注、退火等进行了详细阐述。DN80离心球墨铸管采用5t无芯工频电炉熔炼,出铁前为防止球化衰退按25kg/t加入硅铁合金,浇注采用水冷离心机按60s/支节奏进行浇注,球化包铁水温度控制在1 450~1 470℃,扇形包浇注温度控制在1 380~1 400℃,退火时采用连续式退火炉退火(980℃)。同时,特别针对DN80离心球墨铸管常出现的缺陷进行分析并提出预防措施。     

Effect of Eight Individual Rare-earth Elements on the Graphite Nodule Count of a Thin-section of Spheroidal-graphite Cast Iron

Abstract

Eight rare-earth elements, Y, La, Ce, Pr, Nd, Sm, Dy, and Yb, were added individually to two irons, one containing 0.02% S and the other 0.08% S. After nodularisation, the metal was poured into CO₂ Process sand moulds to produce stepped test-specimens with thicknesses of 3,6 and 9 mm and into shell moulds to provide ‘break-off’ type specimens with a dia of 30 mm. The effect of each of these rare earth elements on the nodule number, and chill formation was investigated and the mechanism of the nodule number increase studied.

The increase in the nodule number differed significantly with each kind of rare-earth element added to the molten iron. The largest rise in the nodule number was with Ce followed in turn by La, Pr, Nd, Sm, Yb and Y. It was seen that the increase in nodule number was more pronounced when the elements were added to the iron with the higher sulphur content. To maximise the increase in nodule number, it was found that the optimum added quantity of these rare-earth elements was almost stoichiometric with the sulphur content of the iron.

X-ray microanalysis of the prepared specimens containing these rare-earth elements confirmed that only sulphides formed in the melts treated with Ce, La, Pr, Nd, or Yb, whilst both sulphides and phosphides formed when additions were made of Dy, Sm or Y. The specimens poured into a metal mould during the eutectic solidification stage, and subsequently quenched showed that graphite had formed on the rare-earth sulphide substrates, but not on the phosphide. It was concluded that the latter cannot act as substrates for the formation of graphite.

Measurement of the average diameters of the rare-earth sulphides (Ce, La, Pr, and Nd) showed that the largest effects upon nodule numbers were associated with elements producing sulphides of smaller diameter. This phenomena may reasonably be explained. A rare-earth sulphide exists as a liquid phase in an iron melt and aggregates until it solidifies, increasing its diameter. The degree of aggregation differs amongst the different rare-earth sulphides, resulting in a different number of substrates for each graphite formation.     

奥-贝球墨铸铁制焊管预弯机下预弯模具的可行性研究

采用球化+二次孕育以及等温淬火工艺制备了球化等级为2级的奥-贝球墨铸铁,比较了奥-贝球墨铸铁、珠光体球墨铸铁和Cr12Mo1V1冷作模具钢的力学性能和摩擦磨损特性。结果表明:奥-贝球墨铸铁具有良好的力学性能和优异的摩擦磨损性能,组织中的贝氏体在摩擦磨损中可以有效地传递应力和起到支撑作用,提高了其抗磨性;较高的硬度和弹性模量以及石墨进入磨损表面润滑,减小了摩擦因数。认为采用奥-贝球墨铸铁制备焊管预弯机的下预弯模具具有可行性。     

球置形成机理的热力学和动力学分析

在对现有的球墨形成长大观点即石墨球化的各种学说进行分析的基础上,从热力学因素－石墨与铁液间的界面能,与动力学因素－石默默周围铁液中球化元素、杂质元素（S,P等）和C、Si等元素的分布及C、Fe元素牟扩散速度等两大方面讨论分析了球墨形成机理各种学说。     

呋喃树脂砂球铁件表层球化不良的防止措施

介绍呋喃树脂砂球铁件表层球化不良的原因和防止方法。由于呋喃树脂砂采用磺酸做固化剂,其所含的S在高温下渗进铸件表层并与Mg化合,使起球化作用的w(Mg)量降低,因而引起球化不良。通过降低再生砂的酌减量(由5.0%降至3.5%),采用型号为G-51-Ⅱ和G-18-Ⅱ的低S固化剂、FQ10防渗S涂料,降低了型砂中的w(S)量,成功解决了铸件表层球化不良的问题。