材料期刊网

Kinetic Model of εCu Particle Dissolution in Welding Induced HAZ of CopperContaining Steel

WANG Qingfeng , CHAI Feng , CAI Jianwei , PAN Tao , SU Hang

钢铁研究学报(英文版)

The kinetics of εCu particle dissolution in the matrix of heat affected zone (HAZ) during welding of a coppercontaining steel was determined by assembling the welding temperaturetime program into a modified Whelan′s solution. The particle dissolution dependence on the degree of “superheating” above the equilibrium transformation is demonstrated from the model. In terms of volume fraction of particle dissolution, the HAZ may be classified into three zones, including the undissolving zone, the partially dissolving zone, and the completely dissolving zone, respectively. The numerical solution was in good agreement with the experimental examination finding. The results of model can be used to quantitatively map the εCu dissolution zone dependence on the peak temperature of welding thermal cycles and understand the evolution of this transformation during welding.

关键词: εCu;particle dissolution;kinetics;welding;steel

Chemistry and Process Optimization of V-Microalloyed N80-Class Seamless Casing Tube

PAN Tao , YANG Cai-fu

钢铁研究学报(英文版)

Chemistry and process optimization of N80 seamless tube was studied by thermo-mechanical simulation tester Gleeble 1500D. Several heats of V-microalloyed steel with different N contents were firstly made at lab in order to simulate N80 seamless tube steel. The results showed that N addition increased strength under condition that toughness was kept at a high level compared with low-N steel. In this study N content with 120-200 ppm enhanced combination performance of strength and toughness whether in-line normalizing process was adopted or not. In-line normalizing process was helpful to improve the toughness though it lowered strength by some degree. However, direct final rolling after tandem rolling (without in-line normalizing) helped increase strength while the toughness remained somehow poor. The above phenomena concerning N80 seamless tube was closely associated with dissolution and precipitation behavior of V(CN). V(CN) precipitation was optimized when N content was increased. When in-line normalizing process was adopted, V(CN) precipitation in austenite increased due to low temperature history during intermediate (in-line) normalizing process. V(CN) particles existing in austenite contributed to grain refinement for VN induced intergranular ferrite, while they weakened precipitation strengthening effect since V precipitating in ferrite wais reduced.

关键词: seamless tube;in-line normalizing;V-N microalloying;reheating;mechanical properties;Gleeble simulation

Frictional HeatInduced Phase Transformation on Train Wheel Surface

SU Hang , PAN Tao , LI Li , YANG Caifu , CUI Yinhui , JI Huaizhong

钢铁研究学报(英文版)

By combining thermomechanical coupling finite element analysis with the characteristics of phase transformation [continuous cooling transformation (CCT) curve], the thermal fatigue behavior of train wheel steel under high speed and heavy load conditions was analyzed. The influence of different materials on the formation of the phase transformation zone of the wheel tread was discussed. The result showed that the peak temperature of wheel/track friction zone could be higher than the austenitizing temperature for braking. The depth of the austenitized region could reach a point of 09 mm beneath the wheel tread surface. The supercooled austenite is transformed to a hard and brittle martensite layer during the following rapid cooling process, which may lead to cracking and then spalling on the wheel tread surface. The decrease in carbon contents of the train wheel steel helps inhibit the formation of martensite by increasing the austenitizing temperature of the train wheel steel. When the carbon contents decrease from 07% to 04%, the Ac3 of the wheel steel is increased by 45 ℃, and the thickness of the martensite layer is decreased by 30%, which is helpful in reducing the thermal cycling fatigue of the train wheel tread such as spalling.

关键词: train wheel steel;thermal cycling fatigue;friction;martensite transformation;thermomechanical coupling

Effect of Tempering Temperature on Microstructure and Mechanical Properties of Steel Containing Ni of 9%

ZHAO Xiqing , PAN Tao , WANG Qingfeng , SU Hang , YANG Caifu , YANG Qingxiang

钢铁研究学报(英文版)

Mechanical properties of quenching, intercritical quenching and tempering (QLT) treated steel containing Ni of 9% were evaluated from specimens subject to various tempering temperatures. The detailed microstructures of steel containing Ni of 9% at different tempering temperatures were observed by optical microscope (OM) and transmission electron microscope (TEM). The volume fraction of austenite was estimated by XRD. The results show that high strength and cryogenic toughness of steel containing Ni of 9% are obtained when the tempering temperature are between 540 and 580 ℃. The microstructure keeps the dual phase lamellar structure after the intercritical quenching and there is cementite created in the Nirich constituents when tempering temperature is 540 ℃. When tempering temperatures are between 560 and 580 ℃, the reversed austenites (γ′) grow up and the dual phase lamellar structure is not clear. The γ′ becomes instable at 600 ℃. When tempered at temperature ranging from 500 to 520 ℃, the increase of dislocation density in the lamellar matrix makes both tensile strength and yield strength decrease. When tempered at 540 ℃ and higher temperature, the yield strength decreases continuously because the C and alloying elements in the matrix are absorbed by the cementite and the γ′, so the yield ratio is decreased by the γ′. There are two toughness mechanisms at different tempering temperatures. One is that the precipitation of cementite absorbs the carbon in the steel which plays a major role in improving cryogenic toughness at lower temperature. Another is that the γ′ and the purified matrix become major role at higher tempering temperature. When the tempering temperature is 600 ℃, the stability of γ′ is decreased quickly, even the transformation takes place at room temperature, which results in a sharp decrease of CharpyV impact energy at 77 K. The tempering temperature range is enlarged by the special distribution of cementite and the lamellar structure.

关键词: steel containing Ni of 9% , tempering temperature , cementite , reversed austenite , cryogenic toughness

CSD-La3TaO7薄膜外延生长行为

王耀 , 李成山 , 于泽铭 , 冯建情 , 金利华 , 王辉 , 张平祥

稀有金属

研究CSD技术制备La3TaO7 (LTO)缓冲层过程中前驱液的热分解行为以及热处理工艺对薄膜取向生长的影响,通过选取恰当的LTO前驱液以及快速升温热处理的方法最终获得了良好c轴织构的LTO薄膜.

关键词: 涂层导体 , 缓冲层 , 化学溶液沉积

Bi3+,Eu3+,Tb3+掺杂Lu3TaO7的发光性能研究

刘文鹏 , 张庆礼 , 杨华军 , 周鹏宇 , 孙敦陆 , 高进云 , 谷长江 , 罗建乔 , 王迪 , 殷绍唐

量子电子学报 doi:10.3969/j.issn.1007-5461.2011.02.018

采用固相反应法制备了Bi3+、Eu3+、Tb3+掺杂的Lu3TaO7.测量了样品的X射线衍射谱、激发和发射光谱及荧光衰减曲线.三种离子掺杂的Lu3TaO7均呈现出强的荧光发射,其中Bi3+具有峰位在431 nm处的一强发射宽带,衰减寿命为16.8μs,Eu3+、Tb3+则表现出稀土离子的特征锐发射峰,衰减寿命分别为1.26 ms和1.20 ms.因此,它们均是具有潜在应用前景的重闪烁体材料.

关键词: 材料 , 闪烁体 , Lu3TaO7 , 发光

PAN基炭纤维经济规模分析

夏春霞 , 闫亚明 , 邓蜀平 , 白光君 , 蒋云峰 , 宋惠森 , 王钰

新型炭材料 doi:10.3969/j.issn.1007-8827.2001.04.013

聚丙烯腈(Polyacrylonitrile缩写为PAN)基炭纤维市场需求旺盛,但由于我国PAN基炭纤维生产企业规模小、产品性能低,产品占领不了市场,企业效益欠佳.通过经济规模方法的分析,就国内现有技术状况和两个样本生产线,用工程技术法对PAN基炭纤维的经济规模进行分析,为我国炭纤维产业化发展提供参考.分析表明,国内PAN基炭纤维经济规模的起点为200t/a～275t/a.

关键词: PAN基炭纤维 , 经济规模 , 工程技术法

PAN/PI复合纤维的结构

李常清 , 袁姗 , 罗荣 , 郭雅明 , 徐樑华

高分子材料科学与工程

将聚酰亚胺(PI)加入丙烯腈-衣康酸-二甲基亚砜体系进行聚丙烯腈(PAN)溶液聚合,湿法纺丝制备了PAN/PI复合纤维.利用流变仪、红外光谱、X射线衍射仪、扫描电镜、差示扫描量热仪等研究了PAN/PI溶液的性质和复合纤维的结构特点.研究发现,加入PI后,聚合物溶液的稳态黏度降低,弹性和粘性模量在低剪切速率区降低;PI作为成核剂,引起初生纤维结晶度增大、晶粒尺寸减小;PI与PAN的溶解性差异导致凝固加快,初生纤维形成皮芯结构;引起原丝体密度减小.PAN/PI纤维在N2下放热量较少,在空气中由于结构疏松放热量较大.

关键词: 聚丙烯腈纤维 , 聚酰亚胺 , 原液改性 , 晶态结构

PAN初生纤维拉伸性能试验研究

谢奔 , 朱波 , 王政 , 井敏 , 王进军 , 张春雷 , 吴益民

功能材料

为了提高聚丙烯腈（PAN）初生纤维的可拉伸性能,将溶液纺丝得到的初生纤维进行不同时间的恒温干燥处理,研究其拉伸性能随干燥时间的变化规律。结果表明,干燥处理可以大幅度提升PAN初生纤维的力学性能,其拉伸强力可达10.3cN,断裂伸长可达263.5%;随着干燥时间的延长,纤维的可拉伸性能增强,经过10h干燥后的初生纤维具有最佳可牵伸性能;而拉伸速率的提高可以有效促进未干燥初生纤维的拉伸变形,而对干燥处理后纤维的拉伸性能的影响不大。用SEM观察纤维断裂形貌发现,PAN纤维的致密性随牵伸比的增加而提高。

关键词: 聚丙烯腈 , 初生纤维 , 干燥 , 拉伸性能 , 断裂形貌

Effect of carbonization atmosphere on the structure changes of PAN carbon membranes

Journal of Porous Materials

PAN carbon membranes were prepared by carbonizing the initial PAN membranes in vacuum and Ar at different temperatures. FTIR, Raman and XRD were applied to study the influence of carbonization atmosphere on the structure changes of PAN carbon membranes. The variations in adsorption peaks of FTIR, the intensity, position and FWHM of the Raman peaks, and microcrystallite parameters from XRD (e.g., d(002), Lc and La) are correlated with the structure change of PAN carbon membranes. Analyses results reveal that vacuum atmosphere can produce PAN carbon membranes with higher order degree than those in Ar atmosphere, although the structures of PAN carbon membranes prepared in the two atmospheres are both amorphous. In addition, vacuum atmosphere can significantly accelerate the degradation reaction of PAN membranes and favors the preparation of carbon membranes with smaller pore size.

关键词: Carbonization;Atmosphere;Carbon membranes;PAN;Structure;molecular-sieve membranes;gas separation membranes;phenolic resin;pyrolysis conditions;thermal-degradation;polyimide;polyacrylonitrile;deposition;graphite;kapton