材料期刊网

THEORETICAL PREDICTION OF THE KINETICS CURVES OF PEARLITIC TRANSFORMATION IN HYPO-PROEUTECTOID STRUCTURAL STEELS

Z.G. Li , H.B. Chang , T. Y. Hsu , Z. Y. Xu , and X. Y. Ruan (Department of Plasticity of Technology , Shanghai Jiao Tong University , Shanghai 200030 , China)(Department of Metallurgical Engineering , Shanghai Technical College of Metallurgy , Shanghai 200233 , China)(Department of Materials Science , Shanghai Jiao Tong University , Shanghai 200030 , China)

金属学报(英文版)

Supposing carbon contents of ferrite phases in pearlite precipitating from austenite in multicomponent steel at temperature T and in Fe-C ystem at T' are the same the pearlite formation temperature diference, can be calculated from the FeX phase diagrams and the equilibrium temperature Al. Using Tp and Fe-C binary thermodynamic model, the driving forces for phase transformation from austenite to pearlite in multicomponent steels have been successfully calculated. Through the combination of simplified Zener and Hillert's model for pearlite growth with Johnson-Mehl equation, using data from known TTT diagrams, the interfacial energy parameter and activation energy for pearlite formation can be determined and expressed as functions of chemical composition in steels by regression analysis. The calculated starting curves of pearlitic transformation in some commercial steels agree well with the experimental data.

关键词: pearlite formation temperature difference , null , null

PREDICTION OF FLOW STRESS OF HIGH-SPEED STEEL DURING HOT DEFORMATION BY USING BP ARTIFICIAL NEURAL NETWORK

J. T. Liu , H.B. Chang , R.H. Wu , T. Y. Hsu(Xu Zuyao) and X.R. Ruan( 1)Department of Plasticity Technology , Shanghai Jiao Tong University , Shanghai 200030 , China 2)School of Materials Science and Engineering , Shanghai Jiao Tong University , Shanghai 200030 , China)

金属学报(英文版)

The hot deformation behavior of TI (18W-4Cr-1V) high-speed steel was investigated by means of continuous compression tests performed on Gleeble 1500 thermomechan- ical simulator in a wide range of tempemtures (950℃-1150℃) with strain rotes of 0.001s-1-10s-1 and true strains of 0-0. 7. The flow stress at the above hot defor- mation conditions is predicted by using BP artificial neural network. The architecture of network includes there are three input parameters:strain rate,temperature T and true strain , and just one output parameter, the flow stress ,2 hidden layers are adopted, the first hidden layer includes 9 neurons and second 10 negroes. It has been verified that BP artificial neural network with 3-9-10-1 architecture can predict flow stress of high-speed steel during hot deformation very well. Compared with the prediction method of flow stress by using Zaped-Holloman parumeter and hyperbolic sine stress function, the prediction method by using BP artificial neurul network has higher efficiency and accuracy.

关键词: T1 high-speed steel , null , null , null , null

B180H1钢板成形性能研究

毕大森 , 武晋 , 张建 , 彭本栋

材料开发与应用 doi:10.3969/j.issn.1003-1545.2009.01.003

高强度烘烤强化(BH)钢是汽车覆盖件用的高强度钢板.本文通过试验对汽车用高强度钢板B180H1的力学性能、成形性能、烘烤硬化性能和抗凹陷性能进行了全面的研究,并与DC04钢板的各项性能进行了比较.使用NADDRG模型对B180H1钢的成形极限进行了预测.试验结果表明,B180H1的力学性能优于DC04,成形性能不低于DC04,且B180H1的烘烤硬化性能及抗凹陷性能方面均优于DC04.B180H1钢板的实冲壳体也具有良好的成形性能.

关键词: 汽车轻量化 , 高强度钢板 , 烘烤硬化 , 成形性能 , 抗凹陷性

INTERNAL FRICTION AND ELASTIC CONSTANTS OF Pd-B-H ALLOYS

Y.L. Chen(Department of Materials Science and Engineering , Zhejiang University , Hangzhou 310027 , China)

金属学报(英文版)

Internal friction measurements on binary and ternary α-phase alloys of Pd with hydrogen and boron have been performed with a torsion pendulum and by observing the cttenuation of ultrasonic pulses. A pronounced damping maximum of binary Pd-B alloys at 220K and measuring frequencies of about 4Hz could not be established at a frequency of 15MH. Ternary Pd-B-H alloys show an additional damping maximum besides the hydrogen Zener effect, which is interpreted in terms of a changed jump frequency of hydrogen in the neighborhood of boron atoms.

关键词: Pd-B-H alioy , null , null , null

Energetics and electronic structure of grain boundaries and surfaces of B- and H-doped Ni3Al

Physical Review B

By using a first-principles plane-wave pseudopotential method, the energetics and electronic structure of Sigma5(210) grain boundary (GB) and the (210) surface of undoped as well as B- and/or H-doped Ni3Al are investigated. The geometric structures of the GBs and surfaces are fully relaxed by minimizing the total energy and interatomic force. The results show that B induces a large lattice expansion but H does not. Both B and H "prefer" to occupy the Ni-rich hole at the GB or surface but not the Ni-deficient one. The segregation energies of B and H as well as the interaction energy between them at the GB and surface are calculated. The calculation indicates that B segregates more strongly to the GB than to the surface, which results in an increase in the Griffith work of the GB and, therefore, in agreement with the experiments, improves the ductility of Ni3Al. Contrary to the case of B, H segregates more strongly to the surface than to the GB, which results in a decrease in Griffith work and confirms H as an embrittler for Ni3Al. The calculation of the interaction energy between B and H demonstrates that B and H repel each other. Consequently, B may block the site of occupation of H at the GB, and restrain the H-induced embrittlement. To understand the mechanism of the obtained energetic features, the electronic densities of states (DOSs) are calculated. A comparison of the total DOSs between the B-doped GB and undoped as well as H-doped ones shows that B increases the hybridization of the GB, which contributes to the enhanced binding of the B-doped GB over the undoped and H-doped ones. When the site of B changes from bulk to GB to surface, the hybridization between B and Ni decreases accordingly. It is proposed that the segregation behavior of B at the GB and surface is dominated by the competition between B(p)-Ni(d) bond energy and the strain energy induced by B. The preference of B for the Ni-rich interstice in Ni3Al is explained by the repulsive interaction between B and Al atoms resulting from the hybridization between their electrons when they are close to each other. The repulsion between B and H can also be explained by the same electronic structure mechanism as that for the B-Al interaction. The segregation of B at surface shifts the DOS of its nearest neighbor Ni to lower energy. This may increase the chemisorption potential energy of H2O on Ni3Al surface and, therefore, decrease the reactivity of the surface, inhibiting the environmental embrittlement of Ni3Al.

关键词: intergranular fracture;environmental embrittlement;polycrystalline;ni3al;water dissociation;first-principles;metal-surfaces;boron;segregation;ductility;hydrogen

耐火H型钢MGFR490B和Q345B高温性能对比试验研究

张善业 , 高怡斐

物理测试

对马钢生产的耐火H型钢MGFR490B和Q345B H型钢进行了对比试验研究,完成了高温拉伸和高温持久两项力学性能测试和对两种钢微观组织的观察研究.结果表明,耐火H型钢MGFR490B的组织为多边形铁素体+珠光体+少量贝氏体混合多相组织,此种组织在高温下能保持很好的稳定性,并能在高温下析出合金碳化物,这对降低耐火H型钢MGFR490B的室温屈强比和保持高温屈强比小的波动范围有益.耐火H型钢MGFR490B获得了比Q345B H型钢好的高温强度性能,这与耐火钢的混合多相组织及添加合金元素密不可分.耐火H型钢MGFR490B在600℃高温下能保持高的强度,并且其持久断裂时间超过3 h,满足耐火钢的性能指标要求.

关键词: 耐火钢 , 高温拉伸 , 高温持久 , 屈强比

耐火H型钢MGFR490B和Q345B高温性能对比试验研究

张善业 , 高怡斐

物理测试

对马钢生产的耐火H型钢MGFR490B和Q345B H型钢进行了对比试验研究，完成了高温拉伸和高温持久两项力学性能测试和对两种钢微观组织的观察研究。结果表明，耐火H型钢MGFR490B的组织为多边形铁素体﹢珠光体﹢少量贝氏体混合多相组织，此种组织在高温下能保持很好的稳定性，并能在高温下析出合金碳化物，这对降低耐火H型钢MGFR490B的室温屈强比和保持高温屈强比小的波动范围有益。耐火H型钢MGFR490B获得了比Q345B H型钢好的高温强度性能，这与耐火钢的混合多相组织及添加合金元素密不可分。耐火H型钢MGFR490B在600 ℃高温下能保持高的强度，并且其持久断裂时间超过3 h，满足耐火钢的性能指标要求。

关键词: 耐火钢 , high temperature tensile high temperature persistent , yield ratio , null

B和H离子顺次注入单晶Si引起的缺陷及其热演变

张蓓 , 张鹏 , 王军 , 朱飞 , 曹兴忠 , 王宝义 , 刘昌龙

原子核物理评论 doi:10.11804/NuclPhysRev.30.04.471

室温下将130 keV，5×1014 cm-2 B离子和55 keV，1×1016 cm-2 H离子单独或顺次注入到单晶Si中，采用横截面试样透射电子显微镜(XTEM)和慢正电子湮没技术(SPAT)研究了离子注入引起的微观缺陷的产生及其热演变。XTEM观测结果显示，B和H离子顺次注入到单晶Si可有效减少(111)取向的H板层缺陷，并促进了(100)取向的H板层缺陷的择优生长。SPAT观测结果显示，在顺次注入的样品中，B离子平均射程处保留了大量的空位型缺陷。以上结果表明，B离子本身及B离子注入所产生的空位型缺陷对板层缺陷的生长起到了促进作用。

关键词: 单晶Si , B和H离子注入 , H板层缺陷 , XTEM , SPAT

Improved hydrogen storage property of Li-Mg-B-H system by milling with titanium trifluoride

Energy & Environmental Science

The Li-Mg-B-H system that is prepared from 2LiH + MgB(2) or 2LiBH(4) + MgH(2) possesses high hydrogen capacity and relatively favorable thermodynamics, but it is greatly restricted in practical hydrogen storage applications by problematic H-exchange kinetics. In the present study, TiF(3) was mechanically milled with a 2LiH + MgB(2) mixture and examined with respect to its effect on reversible dehydrogenation of the Li-Mg-B-H system. Experimental study showed that TiF(3) is highly effective for promoting the two-step dehydrogenation reaction in the Li-Mg-B-H system. Compared to the neat 2LiH + MgB(2) sample, the 2LiH + MgB(2) + 0.01TiF(3) sample exhibits significantly reduced dehydrogenation temperature and markedly enhanced dehydriding rate at both steps. Furthermore, the catalytic enhancement arising upon adding TiF(3) additive was observed to persist well in the hydrogenation/dehydrogenation cycles. Based on the results of phase analysis and a series of designed experiments, the mechanism underlying the observed property improvement is discussed.

关键词: complex hydrides;libh4;tif3;kinetics;naalh4

第27卷B辑作者索引

金属学报

Volu扣ne 27SeriesB1991AUTHOR INDEX CCAO Guanghan(曹光旱)············……6一B科6CAo weijie(曹卫恋)..················……5一B32oCAO Yilin(曹益林)··················……6一B443CHANG Xin(常听)···············……1一B48CHE Guang邻n(车广灿)·············一6一B科0CHEN Erbao(陈二保)···············……6一B410CHEN Jia....

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