Author J.H. Lee 1)
,
K.B. Yoon2)
,
Y.J. Kim3)and U.B. Baek4) 1) Engineering Research Department
,
Korea Institute of Nuclear Safety
,
P.O. Box 114
,
Yoosung
,
Taejon 305600
,
Korea2) Department of Mechanical Engineering
,
Chung Ang University
,
221 Huksuk
,
Dongjak
,
Seoul 156756
,
Korea3) Department of Mechanical Engineering
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Sungkyunkwan University
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300 Chunchun
,
Jangan
,
Suwon 440746
,
Korea4) Failure Prevention Research Center
,
Korea Research Institute of Standards and Science
,
P.O. Box 102
,
Yoosung
,
Taejon 305600
,
KoreaManuscript received 18 October 1998
金属学报(英文版)
Most of the assessment equations for Ct which is a wellknown fracture parameter characterizing high temperature crack growth rates, have limited applicability to constant load conditions after sudden loading. However, crack growth due to creep can also occur under load varying conditions when load rising time is so long that accumulated creep deformation near the crack tip is not negligible.In this paper, the estimation equation of the Ctparameter which can be applied to the case of slow load rising, i.e., (Ct)r, is explained. And the correlation between (Ct)r at the end of the load increasing period and Ct at the beginning of the succeeding load hold period is discussed. Finite element analyses of several cases with various loading conditions were performed and results were presented to show the effectiveness of the proposed Ct estimation scheme. The general applicability of the equation is also discussed.
关键词:
creep
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null
,
null
,
null
,
null
,
null
Solid State Communications
Considering the image potential, we calculate the binding energies of a shallow donor impurity placed on the centre of a quantum box using the variational approach. The results we have obtained show that there is a great difference of the effects of image potential between the cases including impurity ion image potential and including the image potentials of impurity ion and electron simultaneously. The results also show that the image potential is important, especially when the dimensions of quantum box become small.
关键词:
well;gaas-ga1-xalxas;states
周永江
,
熊艳才
,
洪润洲
,
姚惟斌
,
张喆
航空材料学报
doi:10.3969/j.issn.1005-5053.2007.04.003
研究ZL114A合金的拉伸性能和轴向应力疲劳行为(K1=1,R=-1).结果表明,ZL114A合金的疲劳性能与美国A357合金的疲劳性能相当.系统研究了L114A合金疲劳损伤特征,分析疏松、夹杂物等铸造缺陷在疲劳裂纹的形核、裂纹的扩展以及瞬断中所起的作用,表明铸造过程中形成的铸造缺陷数量、尺寸、位置对金属的疲劳性能都有不同程度的影响.
关键词:
ZL114A合金
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疲劳性能
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铸造缺陷
L. H. Lang
,
D. C. Kang
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S. H. Zhang
,
Z. R. Wang
,
S. J. Yuan
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K. B. Nielsen and J. Dancket 1) Department of Materials Engineering
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Harbin Institute of Technology
,
Harbin 150001
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China 2) Aalberg University
,
Denmark
金属学报(英文版)
In this paper, the forming features of tapered rectangular box during hydrodynamic deep drawing are studied by means of FEM.The effect rules of square blank corner corner amount on body wrinkling are recognized and corresponding methods are discussed. At last, the results of FEM are verified by experi- ment.
关键词:
sheet metal forming
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null
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null
王志敏
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顾兰
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李宏伟
,
刘刚
,
成晓芳
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2007.04.016
主要研究了铝合金ZL114A的激光焊接工艺特性.首先对其可焊性进行了摸索,然后探讨了激光焊接工艺参数对焊缝熔深、焊缝宽度以及接头组织和力学性能的影响.结果表明,选择适当的激光焊接工艺参数,如:激光功率、焊接速度、离焦量、保护气体流量等,可以获得高质量的焊缝.组织观察发现,焊缝组织致密、晶粒细小,接头强度可以满足使用要求.
关键词:
铝合金ZL114A
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激光焊接
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工艺参数
Qunqiang FU
材料科学技术（英文）
At first, a series of finite element method (FEM) simulation tests were used to find the critical forming conditions of hot-galvanized sheet steel during the rectangular box drawing processing when constant blank holder forces were applied. According the test results, the reasonable alteration scope of initial variable blank holder force (VBHF) was as 1.9~2.3 T. Then, based on the test productions of blank holder force, 12 typical VBHF curves were applied to perform the simulation tests by the simulation software of DYNAFORM. The simulation test results showed that VBHF had great effects on drawing formability of hot-galvanized sheet steel during the rectangular box drawing. However, the different VBHF curves were applied to control the whole drawing and it would get great different effects. At the same tine, the VBHF had great effects on the maximum thick thinning ratio, but had little effect on the maximum thick incrassation ratio. So, reasonable application of the VBHF would greatly decrease the fractures. When the VBHF profile is taken as curve L, the best effect of drawing formability could be obtained. When curve I is used, contrary effect could be gotten. The other types of curves would cause effects between above two types of VBHF curves. Finally, the actual tests were applied to check the validity of the FEM simulation tests. The results show that the FEM simulation tests are good ways for predicting and optimizing the VBHF.
关键词:
Drawing process
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变压边力
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热镀锌钢板
Journal of Alloys and Compounds
The subsolidus phase relations in the system La2O3-B2O3-P2O5 were investigated. The system can be divided into 12 three-phase regions. There are nine binary compounds and one ternary compound in this system. The ternary compound La7O6(BO3)(PO4)(2) has a monoclinic structure, space groups P2(1)/n, with lattice constants a = 7.0172 Angstrom, b = 17.9125 Angstrom, c = 12.6500 Angstrom, beta = 97.516 degrees, V = 1576.39 Angstrom(3), and Z = 4.
关键词:
La2O3-B-3-B2O3-P2O5 system;phase relations;ternary compounds
陈玮
,
姚长江
,
尹周澜
,
刘新红
耐火材料
doi:10.3969/j.issn.1001-1935.2008.04.009
分别对反应前后的p-Al2O3进行XRD及SEM分析,确定反应前后Al2O3的物相及显微结构变化;测定加入添加剂前后浆体温度与时间的关系,从而确定添加剂对p-Al2O3水化速度的影响;测定加入添加剂前后浆体的黏度变化,从而测定出添加剂对p-Al2O3水化过程的影响.结果表明:1)p-Al2O3属于无定形态;2)在没有添加剂的情况下,p-Al2O3的水化速率很快,同时释放出大量热量,水化产物主要是一水软铝石、三水铝石和拜耳石;3)加入碳酸钠及六偏磷酸钠的混合物为添加剂后,p-Al2O3的水化速率显著降低,释放出的热量显著降低,水化产物主要是一水软铝石.
关键词:
p - 氧化铝
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水化硬化
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不定形耐火材料
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结合剂
何国强
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郑进城
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李卫超
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邹勇志
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曾建民
腐蚀与防护
采用电化学试验和浸泡腐蚀试验研究了不同时效处理的ZL114A合金在3.5%NaCl溶液中的腐蚀行为.利用光学显微镜和扫描电镜对各合金浸泡腐蚀后的形貌进行了观察与分析,并从组织上解释了时效对ZL114A合金腐蚀性能影响的原因.对经固溶(ST)、欠时效(UA)、峰时效(PA)和过时效(OA)处理后ZL114A合金腐蚀性能的分析研究结果表明,固溶状态下合金具有最佳的耐蚀性,Eoorr和Ioorr最小,峰时效状态下合金的耐点蚀和晶间腐蚀性最差,Eoorr和Ioorr最大.
关键词:
ZL114A合金
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时效
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电化学
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耐蚀性
Wenmao HUANG
,
Haihong ZHAN
,
Lingyan XU
,
Zhengbing XU
,
Jianmin ZENG
金属学报(英文版)
doi:10.1016/S1006-7191(08)60091-5
TiB2/ZL114 composites with the density of 2.733 g/cm3 were fabricated through reaction of K2TiF4 and KBF4 (LSM method). The composites were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The internal friction measurements were performed on DTM-II-J dynamic modulus damping analyzer and the mechanisms were investigated. Experimental results indicate that reinforced particles are well-distributed in the matrix and the internal friction value of TiB2/ZL114 composites is up to a maximum of 9.04x10-3, almost twice that of ZL114. The internal friction results form dislocation vibration within the material, the sliding of grain boundary and phase interface, and together with the micro-plastic deformation caused by difference in coefficients of thermal expansion and elasticity modulus of various phases. The average internal friction values of samples with the sizes of 40 mmx4 mmx2 mm, 40 mmx8 mmx2 mm and 40~mm$\times 25 mmx2 mm are 8.83x10-3, 8.89x10-3, and 8.93x10-3, respectively. Thus, the developed composites are of low density, high internal friction, and the sizes of samples have no relation to the internal friction behavior.
关键词:
LSM method
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null
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null
