ZHANG Jiming
,
SUN Weihua
,
SUN Hao
钢铁研究学报(英文版)
A new ultrahigh strength pipeline steel with high yield strength and high impact toughness was fabricated in this work, and mechanical properties and microstructure of the steel were investigated in this paper. The steel exhibited outstanding mechanical properties with yield strength levels of up to 951MPa and Tensile strength levels up to 1023MPa. The sharp notch-toughness with absorbed energy values of 227J/cm2 at Temperatures of -30℃ and %shear of up to 95% in drop weight tear test (DWTT) at temperatures of -20℃ were achieved. It was found that microstructure of the steel comprises a majority of low carbon lath bainite with different sublaths and sub-sublaths, meanwhile there is a high density of dislocation between laths and the dispersed film-like martensite-austenite (M-A) constituents. Most of the precipitates in this steel are duplex type containing Nb and Ti with characterized morphology of cap. The precipitation size is a few to a few tens nanometers.
关键词:
pipeline steel;mechanical properties;lath bainite;precipitate
H.P. Chen and Z.J. Deng (State Key Lab. for Mechanical Behavior of Materials
,
Xi'an Jiaotong University
,
Xi'an 710049
,
China)
金属学报(英文版)
The effect of specimen thinkness on JR resistance curve has been investigated using low and middle strength steels. As the J dominance regime is reached, the initial J-integral values, J(i), are definite even if the elastic component Ji(e) and plastic component Ji(p)vary with the thinkness of specimen. The wider the specimen width, the larger the Ji(e)/Ji and the smaller the Ji(p)/Ji. The crack propagation resistance, dJR/da and dJp/da, decreases, while dJe/da increases linearly with increasing specimen thinness.Based on the above experimental results, an empirical formula dJ/da = α+β. B is given, which can be used to evaluate the safety of practical structural components.A modified J-integral is presented, upon which a new view is Put forward that the increase in crack growth resistance is induced mainly by the increase in the plastic J-integral component with the crack propagation,
关键词:
: fracture mechanics
,
null
,
null
,
null
Journal of Materials Research
The morphology of the dark and bright regions observed by transmission electron microscopy for the Zr(64.13)Cu(15.75)Ni(10.12)Al(10) bulk metallic glass strongly depends on the ion beam parameters used for ion milling. This indicates that the ion beam could introduce surface fluctuation to metallic glasses during ion milling.
关键词:
room-temperature
张淑佳
,
卢炎麟
,
任立义
,
洪起超
金属学报
对20 g钢高温断裂韧性随加载速率的变化规律进行了实验研究.在400℃和500℃下,分别测量了几种加载速率下20 g钢的Ji值.实验结果表明:Ji值随应变速率的增大而有较大幅度的降低;在同一应变速率下,400℃时的Ji值小于500℃时的Ji值;400℃时裂纹扩展比500℃时更快.因此,当温度在400℃附近时更应注意避免超载.
关键词:
断裂韧性
,
null
,
null
周兰花
,
陶东平
,
曾富洪
稀有金属
doi:10.3969/j.issn.0258-7076.2011.04.011
在求解分子相互作用体积模型(MIVM)中的分子对位能参数B(ij),B(ji)时,为避免出现计算超量问题,基于遗传算法,提出了一种新算法--多个体参与交叉遗传算法,并给出了新算法的实现方案.在新算法中,采用了轮盘选种法与优秀个体保存、多个体参与交叉和多点变异等策略;选择B(ij),B(ji)个体时,按照适应度函数值愈大,个体被选中的概率愈大的原则,选择二元合金溶液中一组元活度的计算值与实验测定值之间偏差(σ)建立的适应度函数f(x)最大为优化目标.采用Matlab软件编制新算法下的B(ij),B(ji)计算程序,并分别求算了Cd-Bi,Cd-Pb,Cd-Sn,Bi-Pb,Bi-Sn,Pb-Sn等6组二元合金溶液在773 K下合金溶液的参数B(ij),B(ji)优化值.由B(ij),B(ji)计算优化值和其他一些资料数据,使用MIVM进一步预测773 K下Cd-Bi-Pb,Cd-Bi-Sn,Cd-Pb-Sn,Cd-Bi-Pb-Sn多元合金溶液中组元Cd的活度,模型预测值与实验测定值之间的相对误差低于4.6%,偏差低于0.022,两者吻合很好.结果表明,所提出的多个体参与交叉遗传算法为求解MIVM中的参数B(ij),B(ji)提供了一种有力工具,从而也能提高MIVM对多元合金溶液中组元活度的预测效果.
关键词:
MIVM模型
,
分子对位能参数Bij
,
Bji
,
遗传算法
,
活度
Philosophical Magazine
The error of Equation (15b) in my article [Z.D. Zhang, Phil. Mag. 87 (2007) p.5309] in the application of the Jordan-Wigner transformation does not affect the validity of the putative exact solution, since the solution is not derived directly from that equation. Other objections of Perk's comment [J.H.H. Perk, Phil. Mag. 89 (2009) p.761] are the same as those in Wu et al.'s comments [F.Y. Wu et al., Phil. Mag. 88 (2008) p.3093; p.3103], which do not stand on solid ground and which I have sought to refute in my previous response [Z.D. Zhang, Phil. Mag. 88 (2008) p.3097]. The conjectured solution can be utilized to understand critical phenomena in various systems, whereas the conjectures are open to rigorous proof.
关键词:
3D Ising model;exact solution;conjecture;critical phenomena;ferromagnetism;magnetic phase transition;model;analyticity
