L.I.Mikhoduj (The E. O. Paton Electric Welding Institute
,
NAS of Ukraine
,
Kiev
,
Ukraine)
金属学报(英文版)
Composition and service properties of high - strength low-alloyed steels with 590-980 MPa yield strength,which find an application in Russia, Belorus,Ukraine and other countries of the former USSR in manufacture of welded structures of a powerful mining and transport machinery, are given. Electrodes and wires for main processes of arc welding of these steels have been devel- oped on the basis of a rational use of different systems of alloying (08KhN2GM,08KhNG2M, and also economical systems of type 10G25, ect. ). Main approaches to the technological provess- es of manufacture of structures of high - strength steels are formulated.They are mainly directed to the weakening of de offect of the factors which contribute to a delayed fracture of joints (diffusive hydrogen,unfavourable rates of cooling,level of residual stresses). When there are no stress concentrators (and at a low level of residual stresses) the welded joints of these steels have a good resistance to fatigue and brittle fractures.As a rule, they are prevented with the help of the known approaches.It is shown that in addition to them and due to a proper selection of conditions of welding the life of welded joints of the high - strength steels can be 1. 2 - 1. 4 times in- creased.
关键词:
high-strength steel
,
null
,
null
,
null
L. M. Lobanov (The E. O. Paton Electric welding Institute of the National Academy of Sciences of Ukraine
,
kiev
,
Ukraine)
金属学报(英文版)
A package of work is presented on development of highly effective welded structures, currently conducted by the E. O. Paton Electric Welding Institute. New types of cost - effective and reliable welded struc- tures have been developed, including light - weight building structures, bridge frameworks, TV tow- ers, heavy - duty structures from high - strength steels, large-sized stringer panels and shells, unique structures of a transformable volume. A series of methods of investigations of welding stresses and strains have been created, they being characterized by a high accuracy and information content. The physical and mathematical fundamentals of optical simulation of welded stresses have been estab- lished and the theory of their similarity has been constructed. Holographic methods of investigation of the quality and stressed - strained state of welded joints have been advised. Portable holographic sys- tems for been been developed which allow investigations to be conducted without the vibration - insulation facilities. A non-destructive testing method of residual stresses determination has been elaborated based on ultrasonic probing of the appropriate sections of the welded structure. A new trend has been formed, namely the distortion - free welding of structures, which is based on regulation of the thermal processes during welding with the aim of reduction of the heat input and inducing the preliminary stressed - strained states optimized in terms of welding stresses and strains. Specialized procedures and equipment based on the acoustic emission effect have been developed for diagnostics of welded structures. The technology and equipment have been for ultrasonic impact treatment of welded joints in or- der to improve their fatigue resistance, as well as computerized methods for design of welded joints and structures.
关键词:
welded structure
,
null
,
null
,
null
,
null
Hidetoshi FUJII
,
Yosuke SUMI
,
Manabu TANAKA
,
Kiyoshi NOGI
材料科学技术（英文）
Gas tungsten arc (GTA) welding was performed both in a microgravity environment and in a terrestrial environment, and the arc shapes in both environments were compared. A microgravity condition was obtained using the free fall system at the Japan Microgravity Center. The system can maintain a 10 s microgravity of less than 10-5 g. A water-cooled Cu plate was used to simplify the arc phenomenon. The electric arc current was between 15 and 80 A, and the shielding and atmospheric gas was 99.9995% Ar and its flowing rate was 10 l/min. The polarity was a direct current electrode negative (DCEN). The arc gap was 3 mm and careful attention was also paid to the arc gap in both the terrestrial and microgravity environments being the same. As a result, it was found that no effect of gravity on the arc shape is observed under general welding conditions (over 60 A). When the electric arc current is lower than 25 A, the arc shape is determined by the initial position of the arc root and is constant with time. Accordingly, it can not be judged whether or not the arc shape is affected by gravity for this range. When the electric arc current is between 25 A and 60 A, it is estimated that the arc shape is not affected by gravity though it is occasionally affected by other minor effects.
关键词:
Microgravity
,
null
,
null
,
null
Shude Ji Liguo Zhang Xuesong Liu Jianguo Yang
材料科学技术（英文）
On basis of the subsection welding and the local heating´s reasonable technological parameters obtained by plane experiment, the welding residual stress field of some Francis turbine runner is regulated and controlled. For the experimental plane with a thickness of 16 mm, the effect of subsection welding on decreasing welding residual stress of the prior welding section is obvious when the distance is less than 50 mm away from the end of latter welding section. For the local heating, the best position, where the effect on decreasing the welding residual stress of plane is best, is 60 mm or so away from the edge of heating area. The experimental results of runner show that the subsection welding can make the residual compressive stress engender in the blade dangerous area while the stress value is greatly influenced by the length of the welding section of blade outlet. The local heating can further decrease the value of residual stress near blade outlet, while the local heating processed after heat treatment is better than that processed before heat treatment.
关键词:
Blade
M.Nouri
,
A.Abdollah-zadeh
,
F.Malek
材料科学技术（英文）
The effect of pulsed gas metal arc welding (GMAW) variables on the dilution and weld bead geometry in cladding X65 pipeline steel with 316L stainless steel was studied. Using a full factorial method, a series of experiments were carried out to know the effect of wire feed rate, welding speed, distance between gas nozzle and plate, and the vertical angle of welding on dilution and weld bead geometry. The findings indicate that the dilution of weld metal and its dimension i.e. width, height and depth increase with the feed rate, but the contact angle of the bead decreases first and then increases. Meantime, welding speed has an opposite effect except for dilution. There is an interaction effect between welding parameters at the contact angle. The results also show forehand welding or decreasing electrode extension decrease the angle of contact. Finally, a mathematical model is contrived to highlight the relationship between welding variables with dilution and weld bead geometry.
关键词:
Pulsed gas metal arc welding (GMAW)
,
null
,
null
,
null
,
null
Wei LIU
材料科学技术（英文）
Transformation induced plasticity (TRIP) and twinning induced plasticity (TWIP) effects had been widely studied in single austenite steel. But in duplex γ & α(δ) phase, such as welding materials of stainless steel, they had been less studied. Tensile shear loading experiment of resistance spot welding specimens prepared with 2 mm 301L sheets, was carried out at 15℃ and -50℃. Optical microscopy and scanning electron microscopy (SEM) as well as X-ray diffraction (XRD) were used to investigate the microstructure of weld nugget, and specimens fracture surface. The results showed that the initial weld nugget was composed of 8.4% α(δ) ferrite and 91.6% austenite. Tensile shear load bearing capacity of spot welding specimen at -50℃ was 24.8 kN, 17.7% higher than that at 15℃. About 78.5 vol. pct. martensite transformation was induced by plastic deformation at -50℃, while about 67.9 vol. pct transformation induced at 15℃. The plasticity of spot welding joint decreased with the decline of experimental temperature.
关键词:
301L stainless steel
,
stainless
,
steel
,
Resistance
,
spot
,
wel
Journal of Applied Physics
It has been reported both experimentally and theoretically that the Ba(2+)-doping at the A-site of quantum paraelectric SrTiO(3) suppresses the quantum fluctuations by activating the ferroelectric mode, while the Ru(4+)-doping at the B-site plays the opposite role. For a double-impurity doped SrTiO(3), i. e., Sr(1-x)Ba(x)Ti(1-y)Ru(y)O(3), where the two types of opposite effects compete with each other, we propose an improved transverse-field Ising model in order to investigate the effect of the double-impurity doping on the quantum phase transitions and critical behaviors. The calculated quantum behavior is quite well consistent with experimental measurements. A linear relationship between the quantum critical doping concentrations for Ba(2+) and Ru(4+) is predicted, subsequently validated qualitatively by an anharmonic oscillator model. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3361080]
关键词:
induced phase-transition;srtio3;susceptibility;paraelectrics;batio3;model
李位勇
,
钮小军
,
郑军
,
代义军
,
谢峰
,
陈伟
低温物理学报
本文使用Ansys有限元分析软件，建立三维跑道线圈模型，考虑超导线截面电流密度的非均匀分布特性，计算Bi系高温超导双饼线圈中各区域磁场分布、临界电流分布、电流密度分布和电场分布，从而计算线圈的I～E关系曲线，为超导线圈提供一个更为准确的检验标准，对照线圈的测试结果，用此程序计算的线圈I～E关系曲线与测试曲线吻合的较好．
关键词:
高温超导线圈
,
电磁场
,
I～E关系曲线
王秀梅王琼程振江崔福斋
材料研究学报
通过分析骨涎蛋白和牙本质基质蛋白的功能域, 设计合成了一种非胶原蛋白模拟多肽E8DS (EEEEEEEEDSESSEEDR), 引入胶原蛋白仿生矿化体系, 共同调控磷酸钙晶体的矿化过程。圆二色谱和红外光谱分析结果表明, 多肽E8DS可与钙离子和胶原分子通过静电作用相结合。使用稳态凝胶系统对多肽E8DS的分析结果表明,
E8DS具有很强的调控钙磷盐矿化的能力。多肽的加入有助于胶原纤维的分子组装, 增加了形核位点, 促进了磷酸钙在胶原纤维表面矿化, 使胶原纤维的矿化程度明显提高。
关键词:
有机高分子材料
,
biomineralization
,
non-collagenous protein
,
collagen
,
peptide
