初始条件对铁水预处理脱磷的影响

铁水预处理脱磷是不锈钢冶炼工艺中重要的一环。在大生产数据的基础上,分析初始Si含量、初始P含量、初始C含量以及温度对终点P含量的影响。结果显示,在铁水预处理脱磷过程中,初始Si含量与终点P含量正相关,初始Si含量每增加0.1%,则终点P含量增加约0.002%。二元碱度RCaO/R为3.5~4.0,初始P含量为0.04%~0.06%,终点P含量在0.005%~0.015%之间。在处理温度为1 220~1 320℃,初始C含量为3.8%~4.4%时,初始C含量与终点P含量的对应关系较小。终点P含量随初始温度和处理后温度的升高而升高,同时处理后温度对终点P含量的影响比初始温度的影响更大。     

取向硅钢热力学平衡析出相的计算和分析

为了提高取向硅钢磁性能的稳定性,采用Thermo-Calc软件系统分析了取向硅钢基本合金元素C、Si、Mn、S、Al、N对γ相的转变温度、最大含量、最大含量对应温度,AlN和MnS固溶析出转变温度以及最大析出量的影响。计算结果表明：C含量增加,γ相的转变温度升高、最大含量增加、最大含量对应的温度也升高;Si含量增加,γ相的转变温度降低、最大含量减少、最大含量对应的温度降低;MnS相最大析出量主要受S含量的影响;AlN相最大析出量随N含量增加而大幅增加。     

Ti-Al-Nb系新型合金性能研究

进行了不同Al含量和Nb含量下Ti-Al-Nb系新型合金试样的抗高温氧化性能和耐高温磨损性能测试、比较和分析。结果表明:随Al含量和Nb含量的增加,试样的单位面积质量增重和高温磨损体积先减小后略有增大,抗高温氧化性能和耐高温磨损性能先提升后缓缓下降。14%Al含量下试样的单位面积质量增重和高温磨损体积分别较8%Al含量时减小了53.85%、50%;35%Nb含量下试样的单位面积质量增重和高温磨损体积分别较20%Nb含量时减小了43.75%、41.38%。Ti-Al-Nb系新型合金试样的Al含量优选14%、Nb含量优选35%。     

Cu含量对6013铝合金挤压型材性能的影响

研究了Cu含量对6013挤压型材性能的影响。结果表明：铜含量高的合金，其强度略高于铜含量低的合金，合金中的主要强化相可能为S(A12CuMg)相；6013合金的耐蚀性与铜含量密切相关，随铜含量的增加耐蚀性有所降低。合金综合性能最佳时其铜含量为0．96％。     

连铸保护渣的结晶性能及其模型预测

 利用差热分析仪,研究连铸保护渣的结晶温度与碱度、Na2CO3含量、CaF2含量、Al2O3含量和MgO含量之间的关系,进而通过建立非线性规划模型,对连铸保护渣的结晶性能进行优化设计和模型预测。在本实验渣系条件下,连铸保护渣的结晶温度随着碱度、综合碱度、Na2CO3含量、CaF2含量和MgO含量的增加而升高,随着Al2O3含量的增加而降低。     

不同地区灯盏花总黄酮与野黄芩苷含量比较

[目的]比较不同地区灯盏花中总黄酮与野黄芩苷的含量.[方法]采用紫外分光光度计法测定灯盏花总黄酮含量,以高效液相色谱法测定野黄芩苷含量.[结果] 试验地区灯盏花野黄芩苷含量在1.053%～2.628%,昭通巧家落山所产的灯盏花野黄芩苷含量最高;总黄酮含量在8.845%～15.757%,腾冲芒棒乡1所产的灯盏花总黄酮含量最高.[结论] 不同地区灯盏花的总黄酮与野黄芩苷含量均存在差异.     

安康市农作物硒含量分析

[目的]系统分析陕西省安康市主要农作物的硒含量.[方法]从安康市汉滨区恒口镇和汉阴县蒲溪镇等10个地区采集土壤样品10个,玉米、水稻、油菜、马铃薯、甘薯、大白菜和白萝卜7种农作物样品74个,采用PF6-2双通道非色散原子荧光法测定样品中的硒含量.[结果]安康市10个地区主要农作物具有很高的硒含量,其中大白菜平均硒含量最高,是我国平均含量的48.7～2 651.0倍;白萝卜平均硒含量是我国平均含量的19.0～715.0倍;甘薯平均硒含量虽然最低,但也是我国平均含量的5.9～151.0倍.10个地区中,以紫阳县双安镇各种作物的硒含量最高.[结论]安康市10个地区主要农作物的硒含量均普遍高于我国平均水平,具有很大的开发利用价值,对安康市硒产业的发展意义重大.     

冶炼厂生产废气中重金属污染物排放含量检测分析

针对传统冶炼厂重金属排放含量检测分析方法存在预测结果准确性较差,无法在较短的时间内具体预测排放含量的变化情况问题,开展对冶炼厂生产废气中重金属污染物排放含量检测分析研究。通过基于拉曼光谱的重金属污染物排放含量数据提取、光谱数据处理以及重金属污染物排放含量定量分析,提出一种全新的重金属污染物排放含量检测分析方法。     

低松比片状银粉低温聚合物导体浆料的研究

采用低松比片状银粉为导电相制备低温聚合物导体浆料,讨论了片状银粉松比及其含量、聚氨酯(BT1010)树脂含量、缔合型增稠剂(2026)含量、混合溶剂(NBA+CYC+783慢干水)含量对浆料性能的影响,结果表明片当状银粉质量百分含量为40%,聚氨脂(BT1010)树脂含量为24%,缔合型(2026)增稠剂含量为16%,混合溶剂(NBA+CYC+783慢干水)含量在16%时,银浆的性能最佳。     

转炉终渣TFe含量影响因素研究

对转炉炉渣TFe含量的终点控制情况进行讨论,并在首钢长钢80 t转炉现有操作条件下进行试验;通过试验分析钢液终点碳含量、炉渣碱度R、出钢温度和后吹时间对终渣TFe含量的影响。试验分析结果表明:随着钢液终点C含量的增大,终渣TFe含量有减小的趋势;终渣TFe含量随着终渣R的增大而增大;随着出钢温度的升高,终渣TFe含量逐渐降低。     

The influence of sulfur on stress-rupture fracture in inconel 718 superalloys

The effects of sulfur, with content variations of 15 to 175 ppm, on the stress-rupture and tensile properties in nickel-base alloy 718 are reported. The stress-rupture life dramatically decreased with increasing sulfur content. This was especially noticeable in the ductility loss at 650 °C. Auger electron spectroscopy of stress-rupture tested specimens provided direct evidence of sulfur and phosphorus segregation to grain boundaries and carbide/matrix interfaces. The stress-rupture life and fracture morphology were both found to correlate with the segregation of sulfur at grain boundaries in alloy 718. Sulfur was also preferentially segregated at the carbide matrix surfaces, and phosphorus was found to be distributed on grain boundaries. However, the phosphorus segregation did not correlate with stress-rupture behavior. Sulfur contents in the range of 15 to 50 ppm had little effect on the stress-rupture life. However, the stress-rupture life decreased dramatically with increasing sulfur content above 50 ppm.     

Effect of vanadium on grain boundary segregation of phosphorus in low alloy steels

The phosphorus grain boundary segregation at 853 K was investigated in three low alloy steels with different vanadium content. Kinetic dependence of the phosphorus grain boundary concentration was determined experimentally by means of AES and described theoretically, as well. To assess the influence of the individual alloying elements on the phosphorus segregation, the metal composition of carbide phases at 853 K was predicted by means of thermodynamic calculations and confirmed by experimental measurements (TEM + EDX). The vanadium was found to enhance the phosphorus grain boundary segregation by reducing the amount of dissolved and segregated carbon. Thereby, the equilibrium of mutual displacement C (segregated) ? P (segregated) was shifted to more phosphorus segregation. The results achieved indicate that vanadium indirectly increases sensitivity of low alloy steels to intergranular embrittlement.     

Equilibrium grain-boundary segregation and the effect of boron in B-doped Fe−3wt%Ni austenitic alloy

The equilibrium segregation of boron at grain boundaries and the relation between grain boundary hardening and segregation in B-doped Fe−30 wt%Ni austenitic alloy were studied with the methods of microhardness measurement and Particle Tracking Autoradiography (PTA). It was found that equilibrium segregation of boron at grain boundaries appeared in the alloy as annealed between 650 and 960°C and no segregation of boron appeared above 1050°C. It could be concluded that an excess grain boundary hardening by addition of boron to the alloy was caused by the grain boundary segregation of boron.     

Overview no. 63 Non-equilibrium grain boundary segregation of boron in austenitic stainless steel-II. Fine scale segregation behaviour

A combination of TEM, FIM, AP and IAP has been used to study boron grain boundary segregation in austenitic stainless steels of the types 316L (with 40 ppm or with <1 ppm boron) and “Mo-free 316L” (23 ppm boron). High resolution segregation profiles were determined for cooling rates from 0.29 to 530°C/s for three starting temperatures: 800, 1075 and 1250°C. Boron grain boundary segregation was found after all heat treatments. The segregation behaviour was mainly of the nonequilibrium type after cooling from 1075 or 1250°C whereas equilibrium segregation dominated after rapid cooling from 800°C. The influence of the relative grain orientation on the amount of non-equilibrium segregation was small for general boundaries. However, no segregation was detected at coherent twin boundaries. The binding energy of boron to austenite grain boundaries was estimated at 0.65 ± 0.04 eV for both types of steels. The influence of the composition and boron content of the steels on the segregation behaviour is discussed and the experimental techniques used are presented.     

Nb的非平衡晶界偏聚动力学模拟与实验研究

摘要：Nb是现代高性能钢铁材料中重要的微合金化元素,其在晶界有强偏聚特性。采用3种Nb 空位复合体扩散系数分别对非平衡晶界偏聚进行拟合,根据铁 铌二元合金中Nb在晶界偏聚实验的EPMA测量结果筛选出最终的复合体扩散系数,并据此讨论了低温恒温温度,基体Nb含量,原奥氏体晶粒尺寸对非平衡晶界偏聚动力学的影响,得出了最符合实验结果的铌 空位复合体扩散系数公式。结果表明,在1000℃恒温过程,Nb非平衡晶界偏聚的临界时间在15min左右,临界时间常数为6.57×105。从1200℃固溶态冷却至某低温等温时,随着等温温度的升高临界时间迅速减小,Nb在晶界的最大偏聚量逐渐越小;随着基体Nb含量增加晶界Nb的最大偏聚量线性增加;随着原奥晶粒尺寸的增加临界时间逐渐增大。     

Auger electron spectroscopy study of grain boundary segregation in alloy K-500: Part I. Behavior in as-processed state

Increased interest has been paid to grain boundary segregation in alloy K-500 due to severe intergranular cracking recently observed in forged bars. However, little systematic study of this segregation has been performed so far. A detailed auger electron spectroscopy (AES) study of grain boundary segregation in alloy K-500 has been carried out as a function of alloy chemistry. To determine C segregation, the C and O contamination rates in a vacuum chamber were measured and the necessary condition for C grain boundary segregation determination was established. It has been found that severe C, Al, and Cu segregation to grain boundaries occurred and depended on alloy chemistry. High bulk Ni and low bulk Al promoted C and Al grain boundary segregation, and low bulk Ni and high bulk Al significantly enhanced Cu segregation to grain boundaries. The depth profiles of intergranularly segregated elements also showed different features for high and low Ni content alloys. In high Ni alloys, C and Al levels dropped continuously as a function of distance from the grain boundaries but the Cu level dropped only slightly. In low Ni alloys, the Al and C levels rose from relatively low grain boundary levels to a peak at a certain distance from the grain boundary where the high grain boundary Cu level dramatically dropped. Transmission electron microscope (TEM) observation revealed a grain boundaryγ′-depleted zone followed by a region with coarser and denserγ′ particles in low Ni and high Al alloys but quite uniformly distributedγ′ particles with no depleted zone in high Ni and low Al alloys. These can be explained by the observed segregation behavior. The occurrence of Cu segregation is explained according to available theories about surface segregation in binary Ni-Cu alloys, and the segregation of C and Al to grain boundaries is suggested to be probably due to their interaction with Ni and Cu.     

The intergranular segregation of boron in Ni3Al: Equilibrium segregation and segregation kinetics

The grain boundary B content of high-purity Ni-24 at.% Al alloys containing 0.048, 0.144, 0.240 and 0.480 at.% B (100, 300, 500, 1000 ppm mass) has been determined for samples aged from 1323 to 873 K for sufficient times to attain equilibrium. The B content was derived from Auger electron spectra of the intergranular fracture facets. Many facets were exposed during fracture at ≈ 300 K, and additional facets were formed upon fracturing following hydrogen charging after heat treatment. For each alloy sample, about 25 facets were analyzed. The grain boundary B contents were in the range of 0.5–2.5 at.%. The grain boundary B content increased with decreasing temperature and with increasing bulk B content in the alloys. The energy of binding of a B atom to the grain boundary was calculated using McLean's segregation theory and assuming a unique binding energy for each alloy. The values were in the range of 0.15–0.45 eV/atom, and increased with increasing temperature and with decreasing bulk B content. These results have been rationalized in terms of a spectrum of binding energies for a given alloy. However, when the entropy of adsorption was taken into account, an enthalpy of adsorption of B to the grain boundary of 0.13 eV/atom was obtained, independent of temperatire and bulk B content. This is interpreted to mean that the spectrum of binding energies is quite restricted. The grain boundary B content of these alloys has also been measured as a function of annealing time at 773, 873, 973 and 1173 K. The diffusion coefficient of B in Ni₃Al at 773 K is about 5 × 10⁻²¹ m²/s, and the equilibrium grain boundary B content is attained at about 3000 s. The diffusion coefficient at 973 K is between 10⁻¹⁶ and 10⁻¹⁷ m²/s. The activation energy for diffusion of B in Ni₃Al is between 200,000 and 300,000 J/mol.     

Site competition between sulfur and carbon at grain boundaries and their effects on the grain boundary cohesion in iron

Grain boundary segregation in iron-sulfur-carbon alloys containing up to 100 wt ppm sulfur and up to 90 wt ppm carbon has been investigated with Auger electron spectroscopy (AES). The results show the site compctition on grain boundaries between the segregation of sulfur and carbon. The segregation energy of sulfur is estimated to be 75 kJ/mol. Impact tests of these alloys were carried out. Iron-sulfur alloys with less than 20 wt ppm carbon fractured by the intergranular mode with high ductile-brittle transition temperatures (DBTT’s). Addition of up to 90 wt ppm carbon to the binary alloys prevented the intergranular fracture caused by the grain boundary segregation of sulfur, and decreased the DBTT. Carbon, when segregated to grain boundaries, drives sulfur away from the boundaries and also increases the grain boundary cohesion. The DBTT values of the iron-sulfur-carbon alloys are analyzed in terms of the degree of grain boundary segregation of sulfur and carbon. It is shown that sulfur decreases the grain boundary cohesion of iron more severely than phosphorus if compared at the same degree of grain boundary segregation. Formerly Graduate Student     

Stress enhanced grain boundary segregation of impurity elements in a low alloy steel

Grain boundary segregation isotherms determined by Auger electron spectroscopy (AES) have been employed to elucidate the effect of applied stress on grain boundary chemistry of a low alloy 2.6 NiCrMoV steel. A comparison of grain boundary segregation isotherms of low alloy steel isothermally heat treated at 773 K under constant load and unstressed conditions strongly indicates that stress accelerates grain boundary segregation of impurity elements N, P and S. This enhancement of grain boundary coverage of elements N, P and S is explained in terms of structure of grain boundary, described commonly as an array of linked deltahedra containing holes of varying size and shape.     

3Cr2W8V热作模具钢的稀土合金处理

采用15tEAF冶炼,25tLF精炼,740kg铸锭锻制成Φ110mm的3Cr2W8V钢材。在LF精炼后期,钢中氧含量为29×10^-6,加入0.048%RE合金(%:21~24RE,44Si,3Mn,5Ca,3Ti,余Fe)进行稀土合金处理,稀土元素的回收率为30.78%。检验结果表明,进行稀土处理能够有效地改善3Cr2W8V模具钢共晶碳化物偏析,并显著减少P、Pb、Sn、As、Sb等有害元素在晶界的偏析。