李龙飞李伟孙祖庆杨王玥
金属学报
通过在Gleeble 1500热模拟试验机上进行的单轴热压缩实验并结合SEM和EBSD分析技术,研究了共析钢在A1---Ar1和A1---Ac1温度范围内的两阶段变形对缓冷组织的影响. 结果表明: 共析钢在A1---Ar1温度范围内进行过冷奥氏体形变后, 在A1---Ac1温度范围内再变形时, 可以利用应变量控制再奥氏体化进程, 在一定应变量下获得奥氏体与未溶渗碳体粒子的混合组织, 在随后的缓冷过程中发生离异共析转变, 获得超细化 (α+θ)复相组织, 其中α--Fe平均晶粒尺寸小于3 μm, θ--Fe3C粒子平均尺寸小于0.5 μm.
关键词:
共析钢
,
divorced eutectoid transformation
,
microstructure refinement
,
austenite
,
strain
李尧
,
彭书华
,
杨俊杰
稀有金属
doi:10.13373/j.cnki.cjrm.2014.06.006
在不同脉冲电流条件下对纯钽试样进行拉伸实验,结果表明脉冲电流降低了加工硬化程度,可改善金属的塑性变形能力,并且随着脉冲电流密度的增加,其抗拉强度降低,延伸率提高,当电流密度J=7.64×102 A·cm-2时,延伸率达到50.7％,提高幅度为10％,同时抗拉强度从380 MPa降低至300 MPa,降幅为21％.针对实测的流动应力应变曲线,结合Hollomon模型和Voce模型,考虑脉冲电流对加工硬化的影响,提出H-V综合模型,建立塑性变形本构方程,反映脉冲电流对应力应变的影响.在一定脉冲电流条件下,确定了每种模型的9个最佳参数,利用已确定的模型对拉伸应力应变曲线进行模拟,并与实测的曲线对比验证.模拟结果显示,在变形初期阶段,3种模型之间模拟结果差别都很小,并且模拟值与实际值差异很小,预测准确度较高.随着应变的增大,差异越来越明显,H-V综合模型、Voce模型、Hollomon模型对大应变的模拟精度依次增加,3种模型的趋势线拟合决定系数R2分别为0.99900,0.96409和0.88368,均方差分别为2.42,26.32,39.26.H-V模型模拟效果最佳,能更准确地描述纯钽在电致塑性效应过程中的应力流动行为.
关键词:
电致塑性效应
,
脉冲电流
,
本构方程
,
加工硬化
,
应力
,
应变
王珂
,
刘遵超
,
刘彤
,
曹侃
,
刘敏珊
机械工程材料
建立了简化的管壳式换热器三维模型,利用ANSYS软件对模型的温度场和应力场进行了有限元分析,对比分析了1h和105 h后的应力场,分析了高温蠕变模拟结果.结果表明:由于蠕变变形引起的应力松弛使得105 h后的应力最大值较1h后的出现了明显的下降,最大值出现的位置也发生了变化;经过105 h后换热器的最大蠕变应变达到了0.337,严重蠕变发生的位置主要在封头顶端和筒体中部,与文献报道的失效部位一致,证明了模拟结果的准确性.
关键词:
压力容器
,
蠕变
,
应变
,
有限元模拟
钱文超
,
高关胤
,
吴文彬
,
杨骋
,
童鹏
,
孙玉平
低温物理学报
本文采用脉冲激光沉积方法在LaAlO3 (001)单晶衬底上制备了反钙钛矿GaCMr3薄膜,通过控制制备过程中脉冲激光的能量,研究了不同激光能量条件对GaCMn3薄膜结构与物理性能的影响.分别利用X射线衍射仪、原子力显微镜、超导量子干涉仪和物理性能测试系统,对所制备的薄膜的晶体结构、表面形貌和磁性、电输运性质进行了研究.结果表明,制备的样品均为具有多个晶面取向的反钙钛矿薄膜,且薄膜结构和物性明显随制备激光能量的变化而变化.当激光能量为450 mJ时,制备的薄膜多晶面取向性最弱,结晶性和表面形貌最优电实验所得的薄膜均表现出顺磁-铁磁-反铁磁相转变,然而转变过程比块材较平缓,同时薄膜的电阻率并未表现出块材中的突变特征,我们推测该现象很可能是由衬底的应力及衬底的晶格膨胀对薄膜反常晶格变化的抑制作用造成的.
关键词:
GaCMn3反钙钛矿薄膜
,
不同激光能量
,
多取向结构
,
应力
,
磁电输运性质
L.Li 1)
,
Z. P.Wang. 2)
,
Z.K.Qu 1)
,
D.M.Jia 3) and Z.Jiang 4) 1) Mechanical Engineering College
,
Shenyang University
,
Shengyang 110044
,
China 2) Harbin Research Institute of Welding
,
Harbin 150080
,
China 3) Information Engineering Collage
,
Shenyang University
,
Shengyang 110044
,
China 4) Materials Engineering College
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
A novel test method of measuring the interface bond strength between a thermal sprayed coating and substrate is put forward first in this paper. The test method is simple and reliable, and exists no any inherent shortcoming and controversy. The interface bond strength obtained by the test method is completely the inherent property of the interface and depends only on coating material properties, spray conditions, and technique of depositing the coating. By extensive tests, it is shown that the test tesults are very tepeatable and reliable. Furthermore, from this test, the critical coating thickness under which the coating spall can not emerge is also obtained.
关键词:
coating
,
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
