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稀土在BNbRE重轨钢中的作用机制 总被引:2,自引:0,他引:2
通过化学分析、金相观察和理论分析,研究了稀土在BNbRE重轨钢中的存在状态和含量的变化规律,以及它对钢的硫化物夹杂、微观组织和性能的影响机制。研究发现,对于BNbRE重轨钢,加入大量的稀土并不能增加钢中固溶稀土的含量,固溶稀土的含量均保持在0.0012%以下。少量的固溶稀土可以细化BNbRE重轨钢的奥氏体晶粒和珠光体片层结构。在本实验条件下,BNbRE重轨钢的最佳稀土加入量约为0.02%,此时BNbRE重轨钢的塑性和冲击韧性得到显著提高。 相似文献
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本文通过冶炼不同稀土加入量的重轨钢的试验,研究分析了不同稀土含量在重轨钢中的存在形式以及对组织结构的影响。结果表明:钢中稀土大部分是以稀土氧化物、稀土氧硫化物,稀土硫化物以及复合稀土夹杂形式存在,只有极少量稀土固溶于基体中,其数量随稀土加入量的增加而增高。固溶稀土主要存在于晶界上,少量存在于晶内缺陷等处,固溶稀土降低磷在晶界上的偏聚;高熔点的弥散分布的稀土夹杂物使得钢的铸态组织细化;固溶稀土使得钢的晶粒细化,奥氏体长大倾向降低,并且使珠光体中的渗碳体变薄、变短,且发生弯曲,甚至使之断裂,成为不连续的短棒状渗碳体,珠光体片间距减小。 相似文献
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U76CrRE钢(/%:0.71~0.80C、0.50~0.80Si、0.80~1.10Mn、0.04~0.10V、0.25~0.35Cr、0.02RE)和U75V钢(/%:0.70~0.78C、0.50~0.70Si、0.75~1.05Mn、0.04~0.08V)的冶炼工艺流程为铁水预处理-150 t复吹转炉-LF-VD 280 mm×380 mm连铸,LF精炼后通过喂稀土包芯线加入稀土。对钢的铸坯进行热塑性试验结果表明,加入稀土主要在第Ⅲ脆性区提高V微合金重轨钢的高温塑性,950~1225℃U76CrRE钢和U75V钢的平均断面收缩率Z值分别为83.34%和65.17%,1250℃U76CrRE钢和U75V钢的Z值分别为58%和12%。为防止铸坯出现裂纹,铸坯的矫直温度应≥900℃。 相似文献
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BNbRE重轨属980MPa级高强度耐磨钢轨,它比U74提高耐磨性能1.2倍,提高接触疲劳性能1.1倍,且具有良好的综合性能。稀土能明显改变夹杂物形态,Nb,RE能有效地提高风轨的表面硬度,细化晶粒,减小珠光体片间距。 相似文献
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针对重轨钢“BOF→LF→VD→CC”生产工艺中不同时机添加稀土的效果进行工业试验研究,通过对不同工序加入稀土的重轨钢铸坯进行取样,对样品的稀土含量及夹杂物尺寸、数密度、形貌等进行分析。结果表明:VD后加稀土生产的铸坯中稀土收得率为11.73%,高于LF后加稀土生产的铸坯中稀土收得率2.83%。结合全流程氧含量分析结果,表明稀土加入钢中后就参与脱氧反应,反应产物上浮去除;稀土的加入可有效降低钢中夹杂物尺寸,相较于不加稀土的重轨钢,LF后加稀土和VD后加稀土生产的稀土重轨钢铸坯样品中,夹杂物长度平均值分别由9.28μm降低至7.91、1.42μm,平均宽度由5.71μm降低至4.81、2.27μm;稀土的加入可降低夹杂物评级,对A类、B类、D类夹杂物评级降低效果明显,其中VD后加稀土生产的重轨钢铸坯样品夹杂物评级更优。通过不同工序加入稀土试验对比发现,VD后加稀土的工艺更能提高重轨钢夹杂物变质的能力。SEM及EDS分析结果表明,稀土主要存在于硅钙镁铝系夹杂物中,并使硅钙镁铝系夹杂物由水滴形变为球形,表面发生硫的富集;对硫化锰夹杂分析结果表明,VD后加稀土工艺可使钢中硫化锰与硅钙镁铝系夹杂... 相似文献
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The effects of REinsteel include cleaning,mod-ifyinginclusions and alloying[1 ~4]. With the develop-ment of steel-making and continuous casting process-ing,the fluctuation range of the composition of steelwas mini mized ,the cleanliness of steel was i mpr… 相似文献
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Effect of Rare Earths on Properties of BNbRE Rail Steel 总被引:1,自引:0,他引:1
The development and properties of BNbRE rail steel and the effect of RE on rail steel were studied. The results show that the properties of rail steel (δb ≥980 MPa, δ5≥ 8 % ) can be improved by adding RE and niobium and adjusting the content of C, Si and Mn in steel. At the same time, the abrasion resistance, contact fatigue and fatigue property of BNbRE rail steel are excellent. It also shows that RE in rail steel has the functions of purifying steel, modifying inclusion and micro-alloy action effect. The improved steel-making process enhances the quality of molten steel. Although the content of RE is low, excellent properties of BNbRE rail steel are achieved. 相似文献
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Yu Ning Sun Zhenyan Ji Jingwen Ren Xinjia Wang Yunsheng Wang Longmei 《中国稀土学报(英文版)》2005,23(5):646-646
Effect of Rare Earth (Niobium) on Costed and Hot-Rolled Microstructure and Properties of Heavy Rail Steels 相似文献
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以BVRE重轨钢为研究对象,通过真空冶炼、锻造和轧制工艺制备合格的重轨钢试样.在此基础上,系统研究稀土重轨钢奥氏体晶粒的长大动力学.实验结果表明,随着加热温度的提高,稀土重轨钢奥氏体晶粒呈指数关系长大;随着保温时间的延长,稀土重轨钢奥氏体晶粒长大呈抛物线规律.重轨钢中添加微量的稀土,可以明显降低不同加热条件下的奥氏体晶粒尺寸.模型计算结果表明,重轨钢的奥氏体晶粒长大公式分别为:d4.80=d4.800+ 2.82×1028texp(- 556450/RT)(不加稀土)和d5.34=d5.340 +4.52×1032texp(- 646890/RT)(稀土重轨钢).稀土主要通过晶界的偏聚机制使奥氏体晶粒长大激活能由556450J·mol-1增加到646890J·mol-1,从而抑制奥氏体晶粒尺寸的增加. 相似文献
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Clean high carbon heavy rail steel was prepared by the process of vacuum induction furnace smelting, forging and rolling. Mechanisms of RE on the impact toughness and fracture toughness for clean high carbon steel were investigated. In addition, the appropriate range of RE content for clean high carbon steel was determined. Both the austenite grain size and pearlite lamellar spacing decreased due to small amount of RE, consequently the impact toughness and fracture toughness were improved evidently. When the RE content exceeded a critical value, the pearlite lamellar spacing was increased, because RE was segregated on the austenite grain boundaries, damaged the orientation relationship of pearlite transformation, caused the disorder growth and morphology degenerating of pearlite. With the increasing of RE content, both the impact toughness and fracture toughness of clean high carbon steel were gradually increased at first and then decreased. It was found that when the RE content was between 00081% and 00088%, both the impact toughness and fracture toughness of clean high carbon heavy rail steel were the best. The maximum ballistic work was 212 J (20 ℃) and 122 J (-20 ℃), respectively. The maximum plane-strain fracture toughness was 4567 MPa·m1/2 (20 ℃) and 3704 MPa·m1/2 (-20 ℃), respectively. 相似文献
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