水溶液电解法研究铈对含钛夹杂物的影响

通过水溶液电解法将钛微合金钢中的含钛夹杂物完整地电解提取出来,并采用物理磁选的方法实现夹杂物的无损分离。含钛夹杂物经过超声分散、滴撒夹杂物悬浊液的方式进行制样,并结合扫描电镜研究其形貌。研究发现:随稀土加入量的增加,含钛夹杂物形貌发生不同程度的改变。不添加稀土铈时,钢中含钛夹杂物为典型的长方体形貌。加入0.003 8%稀土铈时,长方体含钛夹杂物转变为正方体含钛夹杂物。稀土加入量为0.005 4%、0.007 2%、0.009 8%时,形成TiC-CeAlO_3、Ti(C,N)-CeAlO_3,含钛夹杂物逐步向椭球形、球形转变,从棱角分明的形状转变为具有光滑曲面的夹杂物并且含钛夹杂物的尺寸减小。随着稀土加入量的增加,钢中含钛夹杂物的析出数量增加,直径小于1μm的含钛夹杂物析出比例增加、含钛夹杂物的平均尺寸逐渐减小。     

稀土加入方法及添加量对合金結构鋼夹杂物的影响

用模内吊挂法对3吨钢锭加入不同量的稀土金属棒,从相当于钢锭上、中、下部的坯料取样,观测分析结果表明,在钢中氧含量约40PPM,硫含量约0.025％的情况下,残留于钢中的稀土基本上以夹杂物状态存在;以稀土改变MnS形态后,继续增加钢中稀土残留量,将增加钢中夹杂物含量,损害钢的纯净度;在这种小型钢锭的凝固过程中,稀土夹杂物也有显著的沉降和聚集现象;这种稀土加入方法适用于以控制夹杂物形态为主要目的的场合。     

稀土Ce-La对SS400钢晶粒度及夹杂物变性的影响

对SS400钢进行了添加稀土Ce-La合金的试验研究,采用光学显微镜和扫描电镜(SEM)观察和分析钢的晶粒度和夹杂物成分及形貌。结果表明,加入稀土后SS400钢晶粒度提高了1～2级;加入0.05%的稀土Ce-La时,硅酸盐夹杂物近似椭圆形;加入量达到0.09%时,硫化物夹杂和硅酸盐夹杂均呈圆形。     

稀土微合金化对BT100H钢基础特性的影响

文章设计了加入稀土和不加稀土两个钢种,研究稀土微合金化对BT100H用钢CCT曲线、淬透性及夹杂物形貌的影响。实验研究表明,稀土微合金化使得BT100H用钢CCT曲线贝氏体区增宽,Ms点上移;稀土微合金化提高BT100H用钢的淬透层深度和淬硬性,稀土的加入使得非金属夹杂物形貌由不规则四边形转变为球形,扫描电镜显示,稀土的加入,使得非金属夹杂物组成由Al、Mg、Ca、S、O构成的复合硫氧化物转变为核心部分是以稀土铝氧化物为主,周围主要由Ca-S-RE夹杂包裹的复合夹杂。     

稀土在轴承钢生产中的应用

稀土在钢中可起到脱氧脱硫的净化作用,控制夹杂物的变质作用,合金化作用等。本文通过石钢京诚生产稀土轴承钢的实际情况,验证稀土提高脱氧脱硫效果,降低夹杂物尺寸、数量,并改变夹杂物形状及成份的效果。随机抽取50炉普通轴承钢GCr15/GCr15SiMn与稀土轴承钢GCr15/GCr15SiMn,普通轴承钢O含量6.2×10~(-6)、最大夹杂物36.21μm、夹杂物面积占比0.022%,稀土轴承钢O含量5.7×10~(-6)、最大夹杂物8.96μm、夹杂物面积占比0.005%。通过对成份、气体、夹杂物数量及尺寸、夹杂物的构成进行对比,确定稀土轴承钢合适的稀土加入量,分析稀土对提高轴承钢纯净度、改善轴承钢性能的效果,以及稀土在轴承钢生产中工业应用情况。     

稀土处理钢中夹杂物对晶内针状铁素体形成的影响

分析了稀土处理钢中夹杂物的特征(夹杂物种类、尺寸分布和体积分数)对微观组织中针状铁素体形成的影响.结果表明,钢中夹杂物种类和体积分数对针状铁素体组织的形成非常重要.稀土氧化物(包含稀土氧硫化物)与铁素体具有低至1.9%的错配度降低针状铁素体在夹杂物表面的形核能垒,从而促使它在稀土氧化物上形核.反之,稀土硫化物与铁素体具有高达42.5%的错配度不能诱导生成针状铁素体组织.此外,微观组织中针状铁素体的体积分数随着夹杂物体积分数的增加而增大,当钢中夹杂物体积分数是9.5×10-4时其体积分数达到53%.      

Ce对10Cr5MoV钢组织性能及碳化物析出行为的影响

文章以10Cr5MoV钢为研究对象,探索Ce不同加入量对实验钢稀土收得率、稀土夹杂物中稀土含量、调质态组织性能、碳化物析出行为等的影响规律。结果表明,随着Ce加入量的增加,Ce收得率逐渐增高,当加入量达到150×10~(-6)时,以固溶态和化合态存在的Ce达到了饱和;夹杂物中的Ce含量则随着加入量的增加持续增长,强度硬度及冲击功均呈先降低后上升,加入量达到150×10~(-6)时出现恶化的现象,延伸率和面塑均得到改善。采用OM、SEM+EDAX、TEM+EDAX分别对不同Ce加入量的实验钢显微组织、析出物进行观察及分析,随着Ce加入量的增加,析出物数量减少,当Ce加入量超过100×10~(-6)时,呈白色M23C6碳化物析出,且随着Ce加入量增加聚集长大。     

稀土渣系电渣重熔H13钢铸锭的成分、组织及夹杂物特征

摘要：稀土(RE)微合金化是开发高品质模具钢的重要手段之一。采用稀土渣系结合电渣重熔实现H13钢铸锭的稀土添加,重点对比研究了稀土氧化铝渣系和氧化铝渣系所制备H13钢铸锭的成分、组织及夹杂物特征,揭示了稀土氧化铝渣系对于H13钢铸态组织的稀土改性作用及机制。结果表明,采用稀土氧化铝渣系或稀土氧化钙渣系均可制备稀土质量分数约0.01%的H13钢铸锭,并分别将S质量分数从电极(原料)的0.01%降低至铸锭的0.005%和0.002%。稀土氧化铝渣系的H13钢铸锭中晶界处有稀土La富集,晶内分布尺寸1~2μm的近球形稀土硫氧化物La2O2S(与基体具有4.7%的较低界面错配度)。相比氧化铝渣系,稀土氧化铝渣系将H13钢铸态组织的二次枝晶平均尺寸从109.6μm减少到84.9μm,液析碳化物和夹杂物平均尺寸从5.1μm减少到3.1μm, 从而改善稀土H13钢铸态组织的均匀性。     

稀土对Gr65钢夹杂物和性能的影响

文章通过工业实验研究了向A572.Gr65钢中加入稀土后对其夹杂物、组织和性能的影响。结果表明,加入稀土之前,钢中夹杂物主要是Al_2O_3和Al_2O_3-Ca O,尺寸约为5μm左右,加入稀土之后,夹杂物变成不足2μm的球状RE_2O_2S夹杂物。并且通过热力学、动力学计算表明,添加稀土之后,钢中最容易生成的夹杂物是RE_2O_2S,而RE~(3+)和Al~(3+)在RE_2O_2S·Al_2O_3中间层中的扩散速率为稀土变质夹杂物的限制性环节。加入稀土后,热轧板微观组织有所细化;冲击和拉伸性能随稀土含量的增加而提高。     

稀土渣系电渣重熔H13钢铸锭的成分、组织及夹杂物特征

稀土(RE)微合金化是开发高品质模具钢的重要手段之一。采用稀土渣系结合电渣重熔实现H13钢铸锭的稀土添加,重点对比研究了稀土氧化铝渣系和氧化铝渣系所制备H13钢铸锭的成分、组织及夹杂物特征,揭示了稀土氧化铝渣系对于H13钢铸态组织的稀土改性作用及机制。结果表明,采用稀土氧化铝渣系或稀土氧化钙渣系均可制备稀土质量分数约0.01%的H13钢铸锭,并分别将S质量分数从电极(原料)的0.01%降低至铸锭的0.005%和0.002%。稀土氧化铝渣系的H13钢铸锭中晶界处有稀土La富集,晶内分布尺寸1～2μm的近球形稀土硫氧化物La_2O_2S(与基体具有4.7%的较低界面错配度)。相比氧化铝渣系,稀土氧化铝渣系将H13钢铸态组织的二次枝晶平均尺寸从109.6μm减少到84.9μm,液析碳化物和夹杂物平均尺寸从5.1μm减少到3.1μm,从而改善稀土H13钢铸态组织的均匀性。     

钙处理对稀土在C-Mn钢中作用的影响

 为了明确钙处理对稀土在C-Mn钢中作用的影响,利用扫描电镜、光学显微镜和超景深三维显微镜对热轧态试验钢夹杂物和显微组织进行了观测,结合热力学计算和冲击断口分析结果,对比研究了稀土和钙-稀土复合处理对C-Mn钢力学性能的影响规律。结果表明,稀土能将钢中典型夹杂物改性为近球形的含硅稀土氧化物的复合夹杂,尺寸细化,长宽比降低。钙-稀土处理后夹杂物变为球形含稀土和钙的复合夹杂,钢洁净度增高;添加钙能将稀土的收得率从7.6%提高到42.4%,有效提高稀土利用率,钙-稀土处理后珠光体所占面积百分比提高,钢的强度提高。证明采用钙处理提高稀土在C-Mn钢中的作用是可行的。     

Effect of Rare Earth Composite Modification on Microstructure and Properties of a New Cast Hot-Work Die Steel

The effects of RE modification on structure and the properties of a new cast hot-work die (CHD) steel were investigated. The grains of the CHD steel are refined by RE modification. With the increase of RE addition, both grain size and inclusion amount are reduced. Appropriate amount of RE results in decrease in inclusion amount and formation of spheroidal inclusions uniformly - distributed in steel, so that the morphology and distribution of inclusions are improved. RE composite modification favors the formation of bainite, austenite and fine lath martensite with dense dislocation. When the residual RE content reaches 0.02 %, no obvious changes in strength and hardness are found, while fracture toughness and threshold of fatigue crack growth are increased. The impact toughness, elongation and reduction of cross sectional area are increased by a factor of two, and thermal fatigue resistance is also improved.     

Application of Lanthanum in High Strength and High

China is quite poor in argent resource. Roughly 80% of this industrial argent is imported every year. In order to improve the situation, we took advantage of rare earth (RE) mineral resource and successfully developed the non-argent Lanthanum-tellurium-copper alloy as a substitute for industry argent-copper. In our research, we were able to successfully apply rare earth lanthanum to copper alloy. The defects as porosity, inclusion, etc. originating from nonvacuum melting processing were controlled. Fine grain was obtained. Meanwhile, the comprehensive properties of the copper alloy, such as strength, conductivity and thermal conductivity were improved. The research results in increasing conductivity and thermal conductivity by 5% and 15%, respectively, while the tensile strength is increased by 6% higher than Ag-Cu alloy. The anti-electric corrosion property is good, and there is no argent-cadmium steam population originating from the electric arc effect. The addition of lanthanum further reduces the content of oxygen and hydrogen.The optimum quantity of the addition of RE lanthanum in the copper alloy is 0.010%～0.020%.     

202不锈钢中稀土Ce对冲击韧性的影响

通过扫描电镜、能谱分析和力学性能检测,研究了加入稀土Ce后202不锈钢冲击韧性的变化情况.研究结果表明:钢中加入稀土Ce可改变夹杂物形态,并且在一定范嗣内可显著提高202不锈钢的冲击韧性.当钢中稀土Ce的质量分数为0.016%时,202不锈钢可获得最佳的冲击韧性.     

稀土复合变质剂对高碳高速钢性能及组织的影响

通过扫描电镜,能谱分析仪和电子探针研究了稀土复合变质剂对离心铸造的高碳高速钢轧辊组织和力学性能的影响。研究结果表明：稀土复合变质剂能细化高碳高速钢轧辊组织,改善碳化物和夹杂物的形态和分布,变质后高碳高速钢辊环在硬度不变的情况下,冲击韧性提高了73．6％。     

The weight-conscious adolescent: body image, food intake, and weight-related behavior

In order to work towards further reduction of vitamin A deficiency in central Java, Indonesia, a social marketing campaign promoting eggs and dark-green leafy vegetables was initiated in March 1996. The nutritional surveillance system (December 1995-December 1996) found the following. The campaign's messages were well noticed. Consumption of at least one egg in the past week increased from 80% to 92% in mothers and from 78% to 92% in children 12-36 months old. It increased in all socio-economic groups and was independent of ownership of chickens. Most eggs had been purchased. The quantity of vegetables prepared increased from 93 to 111 g/person daily and most was purchased. Vitamin A intake increased from 335 to 371 RE/d for mothers and from 130 to 160 RE/d for children. Serum retinol levels increased after the start of the campaign, and were related to egg consumption and vitamin A intake. Because 1. data were collected in such a way that respondents were not aware of the link between data collected and the campaign, and 2. vitamin A status increased and was related to increased consumption of eggs and vitamin A intake, we conclude that the social marketing campaign was successful.     

Effect of Rare Earth on Microstructures and Properties of High Speed Steel With High Carbon Content

The effects of rare earth （RE） on the microstructures and properties of high carbon high speed steel （HCHSS） were investigated. The results show that when suitable RE is added to the HCHSS, the effect of RE on the austenite and eutectic carbides is obvious. The austenite grain and coarse eutectic structure are refined, and flake carbides in the eutectic structures become short and fine. After heat treatment, most of the eutectic carbides are spheroidized and distributed in a uniform manner. The hardness and red hardness of modified HCHSS are slightly increased; impact toughness is greatly increased by 37.81% and reaches 10.17 J/cm^2. The mechanism by which RE improves the structures and properties of HCHSS is also analyzed.     

Effects of Rare Earths on Toughness of 31Mn2SiRE Wear-Resistance Cast Steel

The toughness of 31Mn2SiRE wear-resistance cast steel were increased by means of RE compound modification and high temperature austenitizing. The results show that the microstructures can be refined, needle and network ferrite are eliminated, the dislocation density and the quantity of dislocated martensite are increased remarkably, and the shape and distribution of inclusions are improved by the addition of RE. Therefore, the mechanical properties of the modified steel can be greatly increased, especially the toughness (αK) by 44%, yield strength (σs) by 10%, and elongation (δ5) by 42%.     

Microstructure of Steel 5Cr21Mn9Ni4N Alloyed by Rare Earth

The microstructure, composition and shape of precipitated phase under as-cast and finished product state of 5Cr21Mn9Ni4N steel with different rare earth （RE） amount were studied. Mechanical properties of 5Cr21Mn9Ni4N steels withont RE addition and with RE added by 0. 2% in mass percent were tested respectively. The results indicate that the solid solution amount of RE is about 10^-6 -10^-5 order of magnitude in 5Cr21Mn9Ni4N steel. Dendrite of as-cast condition is refined obviously and dimension of interstitial phase is shortened when RE is added by 0.10%-0.20%. But the microstructure will be coarser if surplus RE is added. Precipitated phase under finished product state distributes evenly in nearly same size with RE added by 0. 2% which leads to a largely improved high temperature mechanical property.