Corrosion Mechanism of Alumina-magnesia Dry Materials for Smelting Manganese/chromium Steel in Coreless Medium Frequency Induction Furnaces

Alumina-magnesia dry materials are widely used in induction furnace linings, but they show different kinds of damage when melting different kinds of alloy steel. In this paper, the chemical composition, phase composition, and microstructure of the post-use dry materials for the working liners melting different kinds of steel were evaluated. Furthermore, the corrosion mechanism of the steel on the furnace lining materials was comprehensively analyzed. The findings reveal a significant ability of the Mn element in the molten steel to diffuse and penetrate into the refractories. Mn oxidizes to form MnO at the steel-refractory interface, and then forms a liquid phase with Al_(2)O_(3). The Cr element is dissolved into corundum and spinel of the refractories, resulting in lattice defects and structural damage of the materials. TiO2reacts with Al_(2)O_(3) to form Al_(2)TiO_(5), which plays a crucial role in preventing crack formation and propagation. Part of Ti4+dissolves into magnesia-alumina(MA), densifying the materials. TiO2also slows down the reaction between the Cr element and refractory components, further improving the corrosion resistance of the materials.

Spheroidization and Ostwald Growth of Carbide in Isothermal Process of Hot-Deformed High Carbon Chromium Cast Steel

In isothermal spheroidizing process,the spheroidization and growth of the carbide formed in hot-deformed high-carbon chromium cast steel at high temperature were investigated.The results showed that the spheroidizing growth of carbide proceeds in such a way that the bigger carbide particles swallow the smaller ones,and the short rhabdoid carbides dissolve and are spheroidized by itself.When the samples were held at 720℃ for more than 3 h,the spheroidization is not obvious.The feature of the process is the size increment and the amount decrement of carbide particles.The empirical equation for growth rate of carbides was obtained.The volume fraction of carbides keeps constant.The growth process agrees well with Ostwald Ripening Law.

Effects of rare earth elements on inclusions and impact toughness of high-carbon chromium bearing steel

High-carbon chromium bearing steels with different rare earth (RE) contents were prepared to investigate the effects of RE on inclusions and impact toughness by different techniques. The results showed that RE addition could modify irregular Al2O3 and MnS into regular RE inclusions. With the increase of RE content, the reaction sequence of RE and potential inclusion forming elements should be O, S, As, P and C successively. RE inclusions containing C might precipitate in molten steel and solid state, but the precipitation tem perature was significantly higher than that of carbides in high-carbon chromium bearing steel. For experim ental bearing steels, the volume fraction of inclusions increased steadily with the increase of RE content, but smaller and more dispersed inclusions could be obtained by 0.018% RE content compared with bearing steel without RE, whereas the continuous increase of RE content led to an increasing trend for inclusion size and a gradual deterioration for inclusion distribution. RE addition could improve the transverse impact toughness and isotropy of bearing steel, and for modified highcarbon chrom ium bearing steel by RE alloying, the increase of RE content continuously increased both transverse and longitudinal im pact toughness until excessive RE addition.

合金元素对中铬铁素体不锈钢组织性能的影响

采用金相、电化学试验、点腐蚀以及盐雾试验等手段,对比分析了添加合金元素Cr、Cu和Mo的常规碳氮中铬铁素体不锈钢与超低碳氮中铬超纯铁素体不锈钢组织性能。试验结果表明:中铬铁素体不锈钢中高C、N含量会导致基体析出大量铬碳化物,造成碳化物周围基体贫铬,影响耐点蚀性能;添加0.2%合金元素Cu提高了不锈钢的电极电位,在3.5%NaCl中性溶液中拥有高的自腐蚀电位和低的自腐蚀电流密度;添加合金元素0.2%Cu和Mo的常规碳氮中铬铁素体不锈钢500h中性盐雾腐蚀试验可以达到超低碳氮中铬铁素体不锈钢同样水平。

小庙岭选矿厂大型球磨机磨矿介质优化试验

为提高球磨机的磨矿效果,获得合格的磨矿产品粒级,针对小庙岭选矿厂磨矿系统改造优化后出现的磨矿产品粒度偏粗、钢球单耗过高的问题,以不同磨矿介质为研究对象,进行了现场应用试验,考察了不同磨矿介质的磨矿效果。试验结果表明:高铬钢球耐磨性优于锻造钢球,应用高铬钢球后,产品粒度波动范围更小,细度稳定,矿石解离度高;采用高铬钢球替代锻造钢球,磨矿平均球耗由0.601 kg/t降至0.511 kg/t,每年可节约钢球成本138.432万元;钢球采用逐步替换方案,一次性投入小,不影响正常生产,该研究结果可为其他企业降本增效、提升经济效益提供借鉴。

Effect of cerium addition on non-metallic inclusions in a high-carbon chromium bearing steel

Effects of varied levels of cerium(28×10-6,65×10^(-6) and 150×10^(-6))on inclusions in a high-carbon chromium bearing steel at different stages(before adding cerium,after adding cerium for 1,5,10 min and ingot)were studied using laboratory experiments.An automatic scanning electron microscope system with energy-dispersive spectroscopy was used to analyze the amount,composition,size and morphology of inclusions in the steel at different stages.When the cerium content in the molten steel increased from 0 to 150×10^(-6),the evolution sequence of inclusions was as follows:Al_(2)O_(3)→CeAl11O18→CeAlO_(3)→Ce_(2)O_(2)S.After 28×10^(-6) cerium was added,Al_(2)O_(3) inclusions were modified into CeAl_(11)O_(18) inclusions in the molten steel and then were further transformed into Al2O3 and CeAlO3 inclusions in the solid steel during cooling.With the addition of 65×10^(-6) cerium,inclusions in the molten steel were modified into CeAlO_(3) and a small number of Ce2O2S inclusions.When the addition amount of cerium increased to 150×10^(-6),inclusions were transformed to Ce_(2)O_(2)S.The size of inclusions in the molten steel decreased obviously with cerium addition.On the other hand,the size of inclusions increased during the cooling process in solid steels of No.1 steel(with 28×10^(-6) cerium)and No.2 steel(with 65×10^(-6) cerium).During the cooling process,unmodified MnS inclusions were precipitated in the solid steel of No.1 steel and wrapped outside the Al2O3 and CeAlO_(3) inclusions to form large complex inclusions.During the cooling process of No.2 steel,the inclusion size of CeAlO_(3) increased due to the collision and polymerization.In the No.3 steel(with 150×10^(-6) cerium),the average size of inclusions decreased rapidly and remained at a lower size during the cooling process,which was beneficial to improving the fatigue life of the steel.

热处理工艺参数对高碳中铬合金钢衬板性能的影响

对0．7%-1．1％C、3%-5％Cr的高碳中铬合金钢进行了等温淬火热处理，采用正交设计确定最佳化学成分配比，得到理想配合的材料韧性和硬度，将所得高碳钢与低碳钢复合铸造双金属复合衬板。试验结果表明，高碳中铬合金钢的硬度为HRC55～62，冲击韧性为6-10J／cm^2；高碳中铬合金钢双金属复合铸造衬板使用寿命比中碳合金钢材质衬板提高50％。

中铬耐磨铸钢的开发及其在磨煤机衬板上的应用

对新型衬板材料——中铬耐磨铸钢作了研究 ,结果表明该材料韧性好、硬度高 ,且热处理工艺简单。在火力发电厂钢球磨煤机衬板上的使用证明 :中铬耐磨铸钢衬板价格低、寿命长。

中铬铸钢及其在湿式磨机衬板上的应用

研究了含碳量对中铬铸钢性能的影响。结果表明，随着合碳量的提高，硬度增加，冲击韧性下降，而腐蚀磨损耐磨性趋向增加；腐蚀对磨损有明显促进作用。装机结果显示：中铬铸钢衬板使用寿命比高锰钢提高６０％。

热变形后的冷却方式对中铬半钢组织与性能的影响

经研究结果得出 ,1.83 %C、6 .15 %Cr中铬半钢 40 %热变形后的冷却方式对组织与性能的影响 。

稀土及热处理对中铬半钢的冲击疲劳性能的影响

研究了稀土元素及热处理对中铬半钢冲击疲劳性能的影响。结果表明 ,稀土与热处理复合作用 ,可加速网状共晶碳化物向孤立的块状转变 ,促进粒状碳化物的析出 ,有效地推迟裂纹的形成 ,降低裂纹扩展速率 ,提高中铬半钢的冲击疲劳抗力。

中频感应炉生产镍铬铁

中频感应炉将不锈钢生产中产生的烟尘冶炼镍铬铁,技术上可行,社会效果和经济效益显著。该项目通过科技创新,发展循环经济资源再生利用,具有广阔前景。

一种耐磨中铬合金钢热处理工艺研究

研制一种中铬合金钢衬板,并探索热处理工艺对中铬合金钢力学性能与微观结构的影响规律。在奥氏体化温度为920~1 000℃区间内,分别进行油冷、空冷淬火热处理。结果表明:随着奥氏体化温度升高,试验材料的硬度与抗拉强度均呈增大趋势,冲击韧性则随着奥氏体化温度的升高先增大后减小,空冷淬火温度为960℃时,材质强韧性达到最佳匹配。当淬火温度低于960℃时,奥氏体均匀化不充分,合金强化作用不明显,强度和硬度偏低;当奥氏体化温度高于960℃时,晶粒长大粗化,冲击韧性降低。

低碳中铬钢渗碳层的耐磨粒磨损性能研究

对低碳中铬钢 (1Cr6 Si2 Mo)固体法稀土渗碳层的组织和耐磨性能与渗碳 2 0钢及淬火 Cr12 Mo1V钢进行了对比试验研究。 1Cr6 Si2 Mo钢的渗碳层内含有大量粒度为 2 .5～ 3.0μm、弥散分布的铬碳化物 ,其尺寸比 Cr12 Mo1V钢中的共晶碳化物小。渗碳淬火后的 1Cr6 Si2 Mo钢试样耐磨粒磨损性能大大优于渗碳淬火后的 2 0钢 ,但不及真空热处理的 Cr12

碳化物对热变形中铬半钢的热疲劳抗力的影响

对不同变形中铬半钢的热疲劳行为进行了试验研究 ,结果表明 :共晶碳化物是热疲劳裂纹产生及扩展的主要部位和通道 ,碳化物破碎程度越大 ,其热疲劳抗力越高 ,热疲劳断口属于脆性断裂。

斜轧中铬半钢磨球的冲击疲劳和磨损性

通过落球和冲击磨损试验 ,研究了斜轧 1.85 %C、5 .86 %Cr中铬半钢磨球的抗小能量多冲击破坏能力和耐磨性。结果表明 :斜轧中铬半钢磨球的冲击疲劳寿命高于铸造半钢磨球。该球经适当的热轧余热热处理 ,可获得较高的抗多冲击破坏能力与耐磨性能。

中低铬锰对高碳多元合金钢耐磨性能的影响

研究铬、锰含量的变化对高碳合金钢硬度、韧性及耐磨性的影响,结果表明:当Cr<3%时,对材料的耐磨性提高的作用较显著,而材料的耐磨性随锰含量的增加而降低。增加相当含量的铬或锰,铬系材料的耐磨性是锰系材料的1～4倍。对提高材料耐磨性而言,铬的作用显著优于锰。材料的耐磨性取决于其硬度和韧性的综合作用,同时还与其基体组织相关。

Cr4WMoV中温中铬耐磨铸钢的研制

介绍一种在 3 90～ 410℃范围内具有较高硬度和较高的回火稳定性的中铬耐磨铸钢 (Cr4WMoV)的组织和力学性能。

热变形量对中铬半钢组织与性能的影响

对经不同热变形量变形的中铬半钢的组织与性能进行了观察、测试及分析 。

热变形中铬半钢碳化物的等温球化行为的研究

对中铬半钢经高温形变后所获得的碳化物在等温球化过程中的球化行为进行了研究。分析认为 ,碳化物是以大粒子吞食小粒子和短条状碳化物分断及棒端溶解自身球化的方式进行球化长大的 ,特点是碳化物尺寸逐渐增大 ,数目逐渐减少 ,当等温球化温度为 6 5 0℃时 ,其长大速度符合经验公式 :Vr=1 2 2 74× 10 -3(0 32 3 +0 0 0 6 2t) 2 (μm/min)