LI Daoming YAO Mei Harbin Institute of Technology
,
Harbin
,
China Box 617
,
Harbin Institute of Technology
,
Harbin
,
China
金属学报(英文版)
The effect of notch depth on the cryogenic fracture behavior has been studied using a low car- bon steel.An analysis was made for the fracture features at T_c~*(cryogenic brittleness-char- acteristic temperature)at which the facture load reaehes a valley value.Furthermore,accord- ing to the experimental results and engineering design practice,a concept of critical notch (crack)'size for cryogenic brittleness,a_c,as well as its limit value a_c~*,was put forward and recommended to be a basic characteristic parameter for controlling the brittleness. Mathematical derivation was carried out to give the expression of a_c and a_c~*,the reliability of which was verified by the modeling tests under both static and cyclic loading conditions.
关键词:
low carbon steel
,
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
杨权
,
谭舒平
钢铁
对先进超超临界燃煤发电机组锅炉高温部件候选材料617合金在750℃下时效1000,2000,3000和5000h后试样的组织稳定性进行了研究.通过OM,SEM,TEM和X射线衍射等方法对时效后晶界及晶粒内的析出物进行了分析.研究发现,时效后试验材料的晶界析出M23C6碳化物;晶内析出γ'相,且γ'相呈颗粒状弥散分布,γ'相尺寸随时效时间的延长而增长.经1000h时效后,试验材料的强度开始增加,并且随着时效时间的延长,强度开始呈现平稳趋势.随着时效时间的延长,试验材料的韧性呈下降趋势.
关键词:
先进超超临界
,
组织稳定性
,
合金
,
析出相
Kazuo KOBAYASHI
金属学报(英文版)
High-temperature fatigue properties were investigated for a nickel-based superalloy 617 as a typical candidate material for high-temperature components using an advanced ultra super critical (A-USC) power plant. Creep-fatigue data obtained by strain-controlled tests at 700℃ was analyzed for the superalloy 617 focused on position of hold at peak strain in comparison with continuously cycled tests. The fatigue life was the shortest with the hold tensile strain wave, which showed mainly intergranular fracture appearance. The life was the longest with symmetrical triangular wave which fractured from the specimen surface, while the wave with the hold compressive strain showed partially intergranular fracture appearance and the life was middle in the both waves. In this study, it is discussed with the creep-fatigue interaction for the superalloy 617.
关键词:
A-USC power plant
L. H. Lang
,
D. C. Kang
,
S. H. Zhang
,
Z. R. Wang
,
S. J. Yuan
,
K. B. Nielsen and J. Dancket 1) Department of Materials Engineering
,
Harbin Institute of Technology
,
Harbin 150001
,
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
,
null
,
null
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
,
变压边力
,
热镀锌钢板
吴赟
,
王珏
,
董建新
,
张麦仓
稀有金属材料与工程
617合金是700℃以上超超临界燃煤电站的备选材料,具有优越的高温持久和耐氧化性能.本文利用热力学计算软件Thermo-Calc及相应的Ni基数据库,对617合金的平衡析出相规律进行了计算分析.结果表明,该合金主要平衡析出相包括y’、σ、μ相以及碳化物M6C和M23C6,Ti对y’相析出量的影响比Al更显著.对617合金标准热处理态的微观组织观察显示,组织均匀,晶界上有连续片状碳化物,再经1180℃/1 h固溶处理后,碳化物部分回溶,在晶界上呈颗粒状分布.
关键词:
617合金
,
超超临界
,
y'相
,
碳化物
江河
,
董建新
,
张麦仓
,
姚志浩
稀有金属材料与工程
研究了700℃超超临界锅炉管用617B合金在720℃/10 000 h、800℃/2000 h和850℃/100 h时效和不同温度50h时效过程中组织稳定性及力学性能变化.结果表明:617B合金在10 000 h长期时效末期组织稳定性较差,γ'相粗化且晶界上有有害相析出;温度对617B合金的组织稳定性影响较大,随着温度升高γ'相急剧粗化,晶内析出相发生转变;合金的硬度主要受γ'相析出规律的影响;720℃时效过程中晶内有拉链状析出相,其种类、结构有待进一步研究.
关键词:
超超临界
,
时效
,
组织稳定性
LIANG Yong LI Ruiguo Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
ChinaInstitute of Corrosion and Protection of Metals
,
Aademia Sinica
,
Shenyang
,
110015
,
China
材料科学技术（英文）
Recent advances in laser coating technology including laser cladding,laser surface alloying and laser vapour deposition in China are reviewed in this paper.
关键词:
laser
,
null
,
null
,
null
,
null
