T.Senthil Kuma
,
V.Balasubramanian
材料科学技术(英文)
Medium strength aluminium alloy (Al-Mg-Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding process for aluminium alloy is frequently TIG (tungsten inert gas) welding due to its comparatively easier applicability and better economy. In the case of single pass TIG welding of thinner section of this alloy, the pulsed current has been found beneficial due to its advantages over the conventional continuous current process. The use of pulsed current parameters has been found to improve the mechanical properties of the welds compared to those of continuous current welds of this alloy due to grain refinement occurring in the fusion zone. A mathematical model has been developed to predict pitting corrosion potential of pulsed current TIG welded AA6061 aluminium alloy. Factorial experimental design has been used to optimize the experimental conditions. Analysis of variance technique has been used to find out the significant pulsed current parameters. Regression analysis has been used to develop the model. Using the developed model pitting corrosion potential values have been estimated for different combinations of pulsed current parameters and the results are analyzed in detail.
关键词:
Pulsed current
,
null
,
null
S.Ravi
,
V.Balasubramanian
,
S.Nemat Nasser
材料科学技术(英文)
Welding of high strength low alloy steels (HSLA) involves usage of low, even and high strength filler materials (electrodes) than the parent material depending on the application of the welded structures and the availability of the ˉller material. In the present investigation, the fatigue crack growth behaviour of weld metal (WM) and heat affected zone (HAZ) regions of under matched (UM), equal matched (EM) and over matched (OM) joints has been studied. The base material used in this investigation is HSLA-80 steel of weldable grade. Shielded metal arc welding (SMAW) process has been used to fabricate the butt joints. Centre cracked tension (CCT) specimen has been used to evaluate the fatigue crack growth behaviour of the welded joints. Fatigue crack growth experiments have been conducted using servo hydraulic controlled fatigue testing machine at constant amplitude loading (R=0). A method has been proposed to predict the fatigue life of HSLA steel welds using fracture mechanics approach by incorporating influences of mismatch ratio (MMR) and notch location.
关键词:
Shielded metal arc welding
,
null
ZHONG Jiaxiang ZHENG Xiuhua XU Zongrui Beijing Institute of Technology
,
Beijing
,
ChinaBAI Dezhong Nei Monggol Machine Works No.2
,
Nei Monggol
,
China Beijing Institute of Technology
,
Beijing 100081
,
China
金属学报(英文版)
Three types of alloy carbides have been observed in tempered steel 4335V:M_3C,M_7C_3 and M_4C_3.The precipitation temperatures are 200—700,400 and 500 ℃ respectively.The com- position,morphologies and distribution patterns of the carbides as well as the relationship be- tween them and as-quenched substructures have been investigated.The influence of the car- bides on the low temperature impact toughness of the steel has also been discussed.
关键词:
steel 4335V
,
null
,
null
Journal of Physics and Chemistry of Solids
The tetragonal distortion for the tetragonal V2+-V-M center in KBr:V2+ crystal is estimated by analyzing its EPR data from two theoretical models, one is the two spin-orbit (S.O.) parameter model where the contributions to EPR parameters from both the S.O. coupling of the central metal ion and that of the ligands are considered and another is the conventional one-S.O.-parameter model where only the contribution from the S.O. coupling of the central metal ion is included. The result from the two-S.O.-parameter model is more than ten times that of the one-S.O.-parameter model. The reasonableness of the former is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.
关键词:
inorganic compounds;crystal fields;defects;electron paramagnetic;resonance (EPR);epr parameters;transition;ions
ZHANG Binhuai LIU Qingcai LI Changwei ZOU Deyu SUN Jinbiao Chongqing University
,
Chongqing
,
China professor
,
Department of Metallurgy and Materials Engineering
,
Chongqing University
,
Chongqing 630044
,
China
金属学报(英文版)
For slag system of CaO-SiO_2-Al_2O_3-MgO-V_2O_5,the time of V reduction to appro ch the dynamical equilibrium is about 6 h,the equilibrium time is not evidently influenced by the ratio CaO/SiO_2 and shortens with the increase of temperature.It the ratio of the weight of slag to that of iron bath is 1/2,CaO/SiO_2 0.8 and tomperature 1773 K.the maxium distribution coefficeent of V reduction is 32.4 and maxium recovery of V is 96.1%.
关键词:
magnetite
,
null
,
null
,
null
徐曼
,
孙新军
,
刘清友
,
董瀚
,
雍岐龙
,
黄金亮
钢铁钒钛
doi:10.3969/j.issn.1004-7638.2005.03.002
通过实验室轧钢试验,研究了三种高V钢轧制状态下的组织的和力学性能,并用透射电镜观察了V(C,N)析出的状况.结果表明,高V钢中可以获得单相的铁素体组织,并可以获得较高的强度,最高的屈服强度值达到525 MPa.对C3钢而言,由V(C,N)析出颗粒的沉淀强化造成的屈服强度增量最大可达244 MPa.透射电镜观察结果表明,高V钢中容易获得相间析出.试验获得的V(C,N)析出颗粒为4~10 nm,经计算分析,该尺寸在V(C,N)最大沉淀强化效果的范围.
关键词:
高V钢
,
单相铁素体组织
,
沉淀强化
,
相间析出
XU Wenchong SUN Fuyu Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing
,
China XU Wenchong Senior Engineer
,
Dept.No.13
,
Central Iron and Steel Research Institute
,
Ministry of Metallurgical Industry
,
Beijing 100081
,
China
金属学报(英文版)
The lattice constants and chemical composition of Ti,Nb and V precipitates with different particle sizes have been measured hy means of CBED and EDAX.It was obtained that the concentration ratio Of Nb and V,C_(Nb)/C_V,and the lattice constants in the Nb-V steel de- crease with the decrease of the particle size of the precipitates,but there is no regularity for tattice constant of Ti,N b and V precipitate against their particle size in the Ti-V-Nb steel.
关键词:
microalloyed steel
,
null
,
null
辛社伟
,
赵永庆
,
曾卫东
,
吴欢
,
杨海瑛
,
李倩
稀有金属材料与工程
配制不同V含量的3种阻燃钛合金,分别测试其在不同热暴露和蠕变工艺下的热稳定性能和蠕变性能,并观察其显微组织.结果表明,随V元素含量的增加,合金热稳定性能和抗蠕变性能提高,并且V元素的含量对热稳定性能和蠕变性能的影响存在一个最佳含量,小于该含量时,V元素含量对热稳定性能和抗蠕变性能影响较大,大于该含量时,含量增加对其性能影响不大.在讨论中指出,V元素对热稳定性能和蠕变性能的影响主要表现在对β相稳定性的影响,对TiCr2相形成过程的影响和与空位的相互作用三个方面,并详细论述了其机理.
关键词:
阻燃钛合金
,
热稳定
,
蠕变
,
力学性能