Fu-Yuan Dong
,
Peng Zhang
,
Jian-Chao Pang
,
Qi-Qiang Duan
,
Yi-Bin Ren
,
Ke Yang
,
Zhe-Feng Zhang
金属学报(英文版)
doi:10.1007/s40195-016-0370-9
Three high-nitrogen stainless steels with different N contents were successfully processed by equal-channel angular pressing for one pass, and their microstructures and mechanical properties were investigated. It was found that the microstructure of the billet was heterogeneous across the billet thickness, resulting in the difference in the mechanical properties due to the different deformation conditions. A relatively low strength, high uniform elongation, and high work-hardening rate for the samples at the bottom of the billet was achieved in comparison with those processed at the top. Meanwhile, it was observed that the density of deformation twins increased with the content of N; accordingly, the strength and elongation of the alloys increase with the content of N, resulting in a good strength-ductility combination.
关键词:
High-nitrogen
,
stainless
,
(HNS)
,
steels
,
Equal-channel
,
angular
,
pressing
,
(ECAP)
,
N
,
content
,
Twinning
,
Strength
,
Ductility
张凌义
,
杨钢
,
黄崇湘
,
陈为亮
,
王立民
金属学报
研究了热轧态1Cr16Co5Ni2MoWVNbN马氏体耐热钢经一道次等径角挤压(ECAP)变形+680℃2 h空冷处理后的微观结构和力学性能. 结果表明: 经ECAP变形后, 马氏体板条大部分已碎化成亚晶粒和位错胞, 第二相纳米粒子(M23C6)分布更弥散均匀; 经随后的退火处理, 发生了回复和部分再结晶, 位错密度有所降低, 形成大量尺寸仅几百纳米的等轴亚晶粒. ECAP变形后材料的屈服强度有很大提高(提高至1400 MPa), 但延伸率和静力韧度均大幅度下降(分别降至7.3%和100 MJ/m3); 随后的退火处理可恢复其塑性(15.4%), 其强度(1044 MPa)和静力韧度(181.6 MJ/m3)均较初始态(922 MPa, 160.7 MJ/m3)高.
关键词:
耐热钢
,
Equal Channel Angular Pressing (ECAP)
,
Strength
,
Plasticity
Cui-Hong Li
,
Qi-Qiang Duan
,
Zhe-Feng Zhang
金属学报(英文版)
doi:10.1007/s40195-016-0371-8
A new parameter, i.e., tearing toughness, was employed to characterize the mechanical properties of some ductile metals (Cu, Cu-2 wt% Be, Cu-Al alloys, and some steels) by using three-leg trousers tearing tests. The experimental results demonstrate that their tearing toughness is not a physical constant and shows a close relationship with the materials’ types and microstructures. It can be inferred that the tearing toughness of different ductile metals has their respective variation range, expectantly, and may be represented by the comprehensive mechanical properties of strength and ductility for various ductile materials.
关键词:
Ductile
,
metals
,
Strength
,
Ductility
,
Tearing
,
toughness
X.J. Wang Q.L. Zeng Q.S. Zhu Z.G. Wang J.K. Shang
材料科学技术（英文）
Effects of electromigration on microstructure, shear strength, and fracture behavior of solder joints were investigated by single-ball shear samples of eutectic Sn-3.8Ag-0.7Cu (SAC) joined by Cu plates at two sides. The electromigration tests were conducted at a current density of about 1.1×103 A/cm2 and a working temperature of about 83°C. The results showed that the shear strength and flow stress decreased greatly after current stressing. Such a decrease was associated with no significant loss of the fracture strain at short electromigration but a great reduction in the fracture strain after long-term current stressing. The variation of the fracture strain with the electromigration time was shown to result from the shift of the fracture surface from the center of the solder towards the intermetallic compound (IMC) interface at the cathode.
关键词:
Strength
Chunfang WANG
,
Maoqiu WANG
,
Jie SHI
,
Weijun HUI
,
Han DONG
材料科学技术（英文）
Martensitic microstructure in quenched and tempered 17CrNiMo6 steel with the prior austenite grain size ranging from 6 μm to 199 μm has been characterized by optical metallography (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The yield strength and the toughness of the steel with various prior austenite grain sizes were tested and correlated with microstructure characteristics. Results show that both the prior austenite grain size and the martensitic packet size in the 17CrNiMo6 steel follow a Hall-Petch relation with the yield strength. When the prior austenite grain size was refined from 199 μm to 6 μm , the yield strength increased by 235 MPa, while the Charpy U-notch impact energy at 77 K improved more than 8 times, indicating that microstructure refinement is more effective in improving the resistance to cleavage fracture than in increasing the strength. The fracture surfaces implied that the unit crack path for cleavage fracture is identified as being the packet.
关键词:
Martensitic steel
,
null
,
null
,
null
,
null
Xinwen ZHU
,
Dongliang JIANG
,
Shouhong TAN
材料科学技术（英文）
An innovative approach has been developed to fabricate reticulated porous ceramics (RPCs) with uniform macrostructure by using the polymeric sponge as the templates. In this approach, the coating process comprises of two stages. In the first stage, the thicker slurry was used to coat uniformly the sponge substrate. The green body was preheated to produce a reticulated perform with enough handling strength after the sponge was burned out. In the second stage, the thinner slurry was used to coat uniformly the preform. The population of the microscopic and macroscopic flaws in the structure is reduced significantly by recoating process. A few filled cells and cell faces occur in the fabrication and the struts were thickened. A statistical evaluation by means of Weibull statistics was carried out on the bend strength data of RPCs, which were prepared by the traditional approach and innovative approach, respectively. The result shows that the mechanical reliability of RPCs is improved by the innovative approach. This innovative approach is very simple and controlled easily, and will open up new technological applications for RPCs.
关键词:
Reticulated porous ceramics
,
null
,
null
,
null
,
null
Chong TIAN
材料科学技术（英文）
Silicon carbide (SiC) foams with a continuously connected open-cell structure were prepared and characterized for their mechanical performance. The apparent densities of SiC foams were controlled between about 0.4 and 1.3 g/cm3, with corresponding compressive strengths ranging from about 13 to 60 MPa and flexural strengths from about 8 to 30 MPa. Compressive testing of the SiC foams yielded stress-strain curves with only one linear-elastic region, which is different from those reported on ceramic foams in literature. This can possibly be attributed to the existence of filaments with fine, dense and high strength microstructures. The SiC and the filaments respond homogeneously to applied loading.
关键词:
Silicon carbide foams
,
carbide
,
foams
,
Apparent
,
density
,
S
张万卿
,
张广成
,
李楠
,
田卫
,
张跃
宇航材料工艺
针对5228A/CF3031层压板生产过程中可能产生的缺陷,设计并制造了孔径超差、不圆孔、孔径分层、孔边打磨过分、边缘分层等5种常见缺陷,并采用注胶法对5种缺陷进行修复.采用ASTM标准对无缺陷试样、缺陷试样、修复试样的拉伸、压缩、弯曲、纵横剪切和层间剪切强度进行了测试,并对试样进行了光学显微镜观察.研究表明孔径超差对拉伸、压缩、弯曲强度影响较大,缺陷试样强度分别下降了11.1％、13.8％、14.4％;孔边打磨过分对纵横剪切强度影响较大,缺陷试样纵横剪切强度下降了25.6％;边缘分层对层间剪切强度影响较大,缺陷试样层间剪切强度下降了27.3％.采用注胶法修复后,5种缺陷试样的力学性能均有一定程度的提高.相比而言,修复后层压板抵抗拉伸、压缩、层间剪切等小形变破坏的效果显著;抵抗弯曲、纵横剪切等大形变破坏的效果不理想.
关键词:
碳纤维
,
层压板
,
注胶法
,
修复
,
强度
马佳
,
刘峰
,
张春
,
张成雷
,
唐庆如
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2014.05.006
运用基于工艺的“laminate modeler”模块创建了复合材料铺层和加筋层合板的三维有限元模型.介绍了一种体单元与壳单元节点融合的方法.以不同的相对节点间距对加筋层合板模型进行了有限元网格划分,采用结构最大Von Mises应力作为标准进行了收敛性分析,得到了一个可适用于其他类似加筋板模型网格创建的合理相对节点间距值1/72.应力计算表明,集中载荷作用下复合材料加筋壁板的初始损伤发生于第八铺层材料主方向的2方向,损伤模式为基体拉伸开裂.发生初始损伤时加筋板结构的极限载荷为75 N.应力集中区较小,且主要分布于载荷作用点附近.集中载荷作用下加筋板的承载效率较低.
关键词:
复合材料
,
加筋壁板
,
有限元
,
建模
,
强度分析
郭金海
,
吕春祥
,
赵鑫
,
田杰
,
居建国
宇航材料工艺
doi:10.3969/j.issn.1007-2330.2014.05.002
连续碳纤维增强树脂基复合材料在航空航天领域是一种关键的结构材料,将性能优异的纳米材料引入复合材料中将有可能提高材料的机械性能.文章介绍了化学气相沉积、化学接枝、电泳沉积等技术在制备碳纳米管-碳纤维多尺度增强体方面的研究进展,并阐述了碳纳米管的引入对复合材料界面性能的影响,提出电泳沉积作为一种经济、有效的技术而具有规模化生产的工业潜力.
关键词:
碳纳米管
,
碳纤维
,
复合材料
,
界面
,
强度
