共查询到18条相似文献,搜索用时 109 毫秒
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设计了新型耐蚀镍铸铁的组织及其化学成分。试验结果表明,除了石墨和奥氏体基体外,还有合金渗碳体存在。该镍铸铁具有良好的耐蚀性能、较好的机械性能与满意的铸造性能。 相似文献
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运用经典动力学和缩聚理论的基本观点对铸铁中石墨形态及形成机理进行了分析研究。结果表明:浇注后的铁水内部由于温度降低而析出的石墨融乳液滴的缩聚与扩散能力,金属液体的粘度及其内部各处由于存在温度梯度而产生的温差点电势场的变化率,导磁性元素硅的晶体四块的自旋速率,其它合金元素的相互影响乃是决定铸铁中石墨形态的关键因素。同时认为,矽晶体团块自旋动量的最大值只有在温差点电势场湮灭的瞬间取得。 相似文献
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研究了钨对低合金白口铸铁显微组织、机械性能和抗磨性的影响。研究结果表明:钨含量在3.5~8.0%的铸铁经适当热处理可形成点状石墨析出;钨含量增加,碳化物的显微硬度增加,抗拉强度和冲击韧性提高;钨系抗磨铸铁具有优良的耐磨性能,达到甚至超过了马氏体高铬白口铸铁。 相似文献
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硅锆合金作为添加剂加入钢中,可起到脱氧、减少氧、氮、硫的有害影响。锆形成的化合物,均匀分布在组织中,可起到细化晶粒,提高材质韧性和淬透性、改善钢种的高温蠕变性能,并能改善低碳薄钢板的深冲性能。当硅锆合金加入铸铁中,能促进石墨生成,有利于石墨化进程,提高铸铁的机械性能和加工性能。国际上已较广泛应用于冶金、铸钢、铸铁等行业。 相似文献
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本文介绍了定量金相方法在合金相变动力学研究中的应用实例,如钢铁材料C-曲线的测定,铸铁固态石墨化动力学研究,合金晶粒或第二相粒子长大动力学分析,再结晶动力学以及珠光体球化动力学的研究等。 相似文献
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测试分析评价了各种铸铁的疲劳裂纹扩展行为;1)铸铁的裂纹扩展速率按球铁,蠕铁及灰铁的顺序依次增大。2)铸铁的石墨形态不同,疲劳裂纹扩展行为相差很大。灰铁由于石墨片在共晶团内相互连接,疲劳裂纹沿着与外应力垂直的石墨片/基体边界连续扩展;对于球铁,当疲劳裂纹尖端扩展至石墨球中时,裂纹尖端被石墨球周围的基体钝化,需重新诱发裂纹。本文提出球铁疲劳裂纹扩展的物理模型。 相似文献
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本文针对包钢焦化设备上的铸铁筛片使用寿命低的问题,从材质成分和铸态组织进行了试验。试验表明合理的化学成分和良好的铸态组织是获得高强度、高硬度的重要保证。稀土镁合金添加到耐磨铸铁中,除可促进石墨球化、净化铁水外,还能细化晶粒、强化基体组织。在细针状的基体上分布有球化良好的石墨,并有10~20%的小块状或点状分布的碳化物的筛片,其耐磨性最好。 相似文献
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阐述了高铝矾土炉衬较高的耐火度、优良的热稳定性、较好的抗渣性、良好的抗蚀性、炉衬的致密化烧结.适用于多种有色金属,普通铸铁、球墨铸铁、及多种合金铸铁,碳钢、合金钢、不锈钢和耐热钢的熔炼.熔炼中金属合金元素烧损低,可超装一倍的金属炉料.炉衬采用低温烘烤、快速升温、高温短时间致密烧结的工艺措施.炉衬的使用寿命多在150炉次左右,最高可达200炉次. 相似文献
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Effect of Rare Earth Elements on Carbide Morphology and Phase Transformation Dynamics of High Ni-Cr Alloy Cast Iron 总被引:6,自引:0,他引:6
EfectofRareEarthElementsonCarbideMorphologyandPhaseTransformationDynamicsofHighNiCrAloyCastIronYangQingxiang(杨庆祥),LiaoBo(廖波... 相似文献
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Fernando D. Carazo Patricia M. Dardati Diego J. Celentano Luis A. Godoy 《Metallurgical and Materials Transactions B》2012,43(6):1579-1595
A new numerical model to describe the microstructural evolution of a eutectic nodular cast iron during its cooling is presented. In particular, equiaxial solidification assuming an independent nucleation of austenite and graphite nodules is considered. In this context, the austenite has dendritic growth whereas the graphite grows with a spherical shape. After solidification occurs, the model assumes that the graphite nodules present in the cast iron continue growing since the carbon content in austenite decreases. Once the stable eutectoid temperature is reached, the alloy undergoes the austenite-ferrite transformation. The nucleation of the ferrite takes place at the contour of the spherical graphite nodules where austenite has low carbon concentration. A ferrite shell surrounding the graphite nodules is formed afterward by means of a process governed by carbon diffusion. Then, a ferrite-pearlite competitive transformation occurs when the temperature is below the metastable temperature. This thermo-metallurgical model is discretized and solved by means of the finite element method. The model allows the computation of cooling curves, fraction evolution for each component, and size and distribution of graphite nodules. The present numerical results are compared with experiments using standardized Quick-cup-type cups, and satisfactory numerical predictions of the final microstructure and cooling curves are achieved. 相似文献
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K. Theuwissen J. Lacaze L. Laffont J. Zollinger D. Daloz 《Transactions of the Indian Institute of Metals》2012,65(6):707-712
It is well-known that if certain trace elements are present in cast iron melts the morphology of the graphite precipitates can be altered. In order to understand the effect of doping elements on primary growth of graphite, pure Fe?CSb alloys were prepared by induction melting. They were then placed in graphite crucibles and heated to a temperature above the Fe?CC eutectic so that the charge became saturated in carbon and melted. To obtain Fe?CCe alloys, metallic Ce was added at the bottom of a graphite crucible and covered with iron, and then heated as for the Fe?CSb charge. In both cases, the melt was then cooled and held slightly above the eutectic temperature so that primary graphite crystals, which had nucleated on the crucible walls and then detached from it, could grow freely in the melt. The influence of the added elements on graphite growth was revealed by the change in the shape and distribution of the crystals compared to those obtained in similar experiments carried out with pure Fe. The experiments were made in air and vacuum so as to point out possible interactions between the elements present in the melt and oxygen. 相似文献