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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. 相似文献
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Edward Fraś Marcin Górny Hugo F. Lopez Magdalena Kawalec 《Metallurgical and Materials Transactions A》2013,44(6):2512-2522
In the current study, an analytic solution is considered to explain the influence of sulfur on the transition from graphite to cementite eutectic in cast iron. The outcome from the current study indicates that this transition can be related to (a) the graphite nucleation potential (directly characterized by the cell count and indirectly by the nucleation coefficients; (b) the eutectic graphite growth rate coefficient; (c) the temperature range between the equilibrium temperature for graphite eutectic and the formation temperature for cementite eutectic; and (d) the liquid volume fraction, after pre-eutectic austenite solidification. In addition, the absolute and the relative chilling tendencies, as well as critical cooling rates including the chill width of the cast iron can be predicted from the current study. The analytic model was experimentally verified for castings with various sulfur contents. It is found that the main role of sulfur on the transition from graphite to cementite eutectic is through its effect on lowering the growth coefficient, and hence, the graphite eutectic growth rate. In addition, it is found that with the increasing sulfur content, the critical cooling rate is significantly reduced, thus increasing the absolute and the relative chilling tendency values, including the chill width. 相似文献
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球墨铸铁轧辊的补缩,一般是采用砂型明冒口和浇注后每隔20-25分钟用过热铁水点冒口1-2次的办法解决,这样的工艺使冒口金属消耗量占轧辊毛重的15%左右。为了节约金属和提高轧辊上辊颈质量,本研究工作是采用铝型膨胀发热剂单独使用或与绝热套组合成的保温冒口,以取代原工艺以稻草灰覆盖的干砂型冒口。经过实验室及现场对此实验表明:采用保温冒口以后,球墨铸铁共晶凝固时间延长了33-62%,缩孔形状由倒锥形变为盆形,轧辊冒口的致密段高度增加,省去了用过热铁水点冒口的工序。冒口高度可以降低25~50%,节约冒口金属量20~50%。研究工作表明:采用保温冒口是解决球铁轧辊补缩的最合理、经济而简便的措施。 相似文献
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Solidification and Room Temperature Microstructure of a Fully Pearlitic Compacted Graphite Cast Iron
Alexandre Freulon Jon Sertucha Jacques Lacaze 《Transactions of the Indian Institute of Metals》2018,71(11):2651-2656
Compacted graphite cast irons are rapidly developing for they have better mechanical properties than lamellar graphite cast irons and present less porosity than spheroidal graphite cast irons. For many applications, an as-cast fully pearlitic matrix would be desired which can hardly be achieved when graphite is compacted. Addition of manganese, copper and tin are thus made as these elements are known to be pearlite promoters. However, their amount should be limited so as to avoid detrimental effects amongst which are heterogeneities in the matrix properties which impede easy machining. In the present work, a compacted graphite cast iron containing 0.3 wt% Mn, 0.8 wt% Cu and 0.1 wt% Sn was cast in sand mould and in standard thermal analysis cup. The cup sample showed a nearly fully pearlitic matrix and was selected for further study. The characterization consisted of measuring and correlating the distributions of pearlite interlamellar spacings and microhardness values. An attempt was made to look for the effect of solidification microsegregation on microhardness which did not reveal any trend. 相似文献
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高温下奥—贝蠕铁的组织与性能 总被引:1,自引:0,他引:1
奥—贝蠕铁是继奥—贝球铁之后发展起来的新型工程材料之一,也是世界上正在开发的材料。本文系统地提供了奥—贝蠕铁的制取工艺,奥—贝蠕铁的组织特征及其在常温及随温度提高力学性能变化的规律。研究表明,以稀土硅铁为蠕化剂,所制取的蠕化率大于90%、基体以铁素体为主的蠕墨铸铁,经等温淬火后,可稳定地获得奥氏体—贝氏体基体(以下简称奥—贝蠕铁),它有较好的综合性能,在常温下σb=820~937.5MPa,δ=0.40%~0.78%;在600℃时,σb=158~187MPa,δ=4.00%~7.84%,仍超过HT150的常温性能。当低于300℃时组织和性能稳定性较好,是适宜的工作温度范围 相似文献
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国内外广泛采用梯度石墨结构铸铁作为瓶罐类玻璃模具材料,但使用寿命存在显著差距。对实际使用的梯度石墨铸铁模具进行了对比分析,结果表明:国内外模具材料石墨形态与分布相似,由内侧的D型石墨过渡到外侧的A型石墨时,材料抗压强度下降;石墨形态为D型时,抗压强度与基体显微硬度呈线性关系;进口玻璃模具材料基体组织基本为铁素体,塑性较好,国产玻璃模具材料基体含约10%(体积分数)的片状珠光体,强度高,但是塑性较差;玻璃模具使用寿命与模拟热疲劳寿命趋势一致,均属于低周疲劳破坏,寿命主要决定于模具材料的塑性。 相似文献
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通过恒应变压缩实验研究了锻态TC10钛合金的高温变形行为和组织演变规律,变形温度为800~920℃,应变速率为0.01~10 s~(-1),变形量为60%。研究结果表明:降低变形温度、提高应变速率,流变应力会在变形初期迅速增加,而显微组织没有明显变化,当流变应力达到最大值后随着动态再结晶的发生而逐渐降低。提高变形温度、降低应变速率,能够为动态再结晶提供能量,细化组织并降低流变应力。综合分析表明:在变形温度为840~900℃,应变速率为0.01~0.1 s~(-1)的参数范围内进行热变形可以获得性能优良的TC10钛合金产品。 相似文献
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使用悬浮液进样 ,不进行溶样处理 ,最低限度地减少了样品处理过程中的沾污。选用乙醇作溶剂 ,降低了空白。方法操作简便 ,测定下限低 相似文献
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R. H. Jones S. M. Bruemmer M. T. Thomas D. R. Baer 《Metallurgical and Materials Transactions A》1982,13(2):241-249
Antimony, segregated to grain boundaries of iron, was found to be five times more effective than sulfur in promoting intergranular
fracture of iron when tested in IN H2SO4 at cathodic potentials. A decrease in the ductility of iron accompanied the fracture mode change at increasing cathodic potentials.
The effectiveness of antimony relative to sulfur was determined from straining electrode tests on iron and iron + 250 appm
antimony alloys heat treated at 800 °C and 600 °C to produce different grain boundary chemical compositions. Grain boundary
compositions were determined by Auger Electron Spectroscopy (AES). Similar grain boundary sulfur concentrations of 0.2 monolayers
were observed by AES for the iron and iron + 250 appm antimony alloy after an anneal of 240 hours at 600 °C, while 0.08 monolayers
of antimony was observed for the iron + 250 appm antimony alloy. These results suggest that sulfur and antimony do not compete
for grain boundary sites. 相似文献
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以低碳含磷钢为研究对象,通过分析不同卷取温度时(分别为600、650和700 ℃)热轧态和冷轧退火态的显微组织和力学性能以及退火再结晶动力学行为,研究了微钛(0.015%)处理对钢的组织和性能的影响.研究结果表明,热轧卷取温度对低碳含磷钢的显微组织和力学性能影响很小,但微钛处理后,低碳含磷钢的再结晶动力学受到延迟,特别当卷取温度为600 ℃时,不但热轧态和冷轧退火态的强度提高,而且力学性能对卷取温度和退火温度的敏感性增加;随着卷取温度的降低,热轧态和冷轧退火态的强度提高,且冷轧退火态强度随着退火温度升高而降低的幅度增加.微钛处理对含磷钢组织和性能的影响与钛析出相的粗化行为有关. 相似文献
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EfectofRareEarthsandNitrogenonGraphiteStructureofGrayCastIronZhaiQijie(翟启杰),ZengQi(曾奇)(FoundryInstitute,UniversityofSciencea... 相似文献
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CAIQi-zhou WEIBo-kang TANAKAYuichi 《钢铁研究学报(英文版)》2005,12(3):40-45
DuctileironwasdevelopedbyMorrogh[1]in 1940s.Theappearanceofaustemperedductileiron (ADI)in1970sessentiallyaffectedthemetallurgical researchofductileiron[2,3].ADIhasverygood properties[4-15].Itisproducedbyaustemperingcon ventionalductileiron,andthemicrostr… 相似文献