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81.
Electrochemical investigations on low-Si alloyed steels with Si content ranging from 0.25 to 3.2 wt.% were carried out in a 0.1 M NaCl borate-buffered solution (pH 8.4) in reducing conditions at 90 °C. Silicon as an alloying element was proved to degrade at first the steel ability to passivate. For longer immersion times, protective effects developed more efficiently on the steel containing 3.2 wt.% silicon. Passive layers electrochemically formed in the transpassive domain on the steel containing 3.2% Si were shown to be significantly different from those grown at rest potential.  相似文献   
82.
利用2、4和14mm的X60钢紧凑拉伸试样进行同样应力水平、固定应力比(R=0.1)的疲劳裂纹扩展试验,揭示出高韧性管道钢的疲劳裂纹扩展存在显著的厚度效应。由于应力水平低,相应的离面应力也低,不足以导致分层开裂,因此,裂纹端部的三维应力约束随厚度增加而增大。4mm试样的疲劳裂纹速率远高于2mm试样,但厚度再增大,裂纹扩展速率不再有显著变化。进一步对表面裂纹试样进行疲劳裂纹扩展试验,并用勾线法纪录裂纹扩展情况,利用穿透裂纹的da/dN-ΔK曲线预测表面裂纹扩展,用2mm厚试样的数据控制裂纹表面长度的扩展,用14mm厚试样的数据控制裂纹底部沿厚度方面的扩展,得到了与表面裂纹扩展实验吻合很好的预测结果。  相似文献   
83.
The suitability of round clinching tools for high strength structural steel   总被引:1,自引:0,他引:1  
J. P. Varis   《Thin》2002,40(3)
The use of light gauge steel framing is increasing rapidly. New methods for joining frames are being sought. One of the most promising methods is clinching. Clinching has been used for almost 20 years. There has been much research into the method, the tools, suitable materials and applications. Few articles have been published concerning clinching of high strength structural steels, which are currently the most relevant materials for house construction.This study included 11 different clinching methods. In total, 469 test pieces were produced. Despite the high strength of the materials, all the clinching methods that were examined could be used satisfactorily. The most significant result was that a round tool is appropriate for all the materials tested. In fact, in comparison with results obtained using other types of tool, when the methods were ranked by maximum shear load capacity, the round design appeared in the top three classes seven times out of nine.  相似文献   
84.
提高自蔓延陶瓷内衬钢管耐蚀性研究的进展   总被引:1,自引:0,他引:1  
广泛应用于石油,化工,能源等领域的钢管,除了要有高强度外,还要有良好的耐蚀性。自蔓延高温合成技术是制备耐蚀钢管的新技术,具有工艺简单,成本低和产品耐蚀性能好等特点。介绍了自蔓延高温合成陶瓷内衬钢管的原理和提高陶瓷内衬钢管耐蚀性的措施,展望了耐蚀陶瓷内衬钢管在工业生产上的应用前景。  相似文献   
85.
The objective of this study was to evaluate the effectiveness of sodium benzoate as an inhibitor to slow down or prevent atmospheric corrosion/discoloration of the local mild steel during storage in the Arabian Gulf region. Test specimens were prepared from locally produced reinforcing steel products. The inhibitor solution was applied on steel specimens at a concentration of 100 mM for 1 day at room temperature. Wooden exposure racks were used to hold as-received and inhibitor-treated specimens during atmospheric exposure for different periods. Corrosion was evaluated through weight loss determination and electrochemical technique. As expected, the Arabian Gulf atmosphere was corrosive on the as-received local mild steel. On the other hand, treatment of steel with sodium benzoate lowered its corrosion rate during initial days of its exposure to atmosphere. However, atmospheric corrosion inhibition performance of sodium benzoate deteriorated with exposure time after 30 or more days of atmospheric exposure, and the corrosion rates of sodium benzoate-treated specimens reached that of the unprotected specimens at the end of 90 days of atmospheric exposure.  相似文献   
86.
心电图信号的频域分析   总被引:2,自引:1,他引:1  
提出了一种简便有效的、由心电图(ECG)曲线提取QRS-T复合波的新方法,从而获得P波(当房颤未发生时)或f波(当房颤时);利用功率谱、自相关、互相关等信号处理技术,对它进行了处理和分析,特别是,比较了未房颤时和发生房颤时的相关信息的显著差别。  相似文献   
87.
纤维混凝土在水工建筑工程中的应用(上)   总被引:1,自引:0,他引:1  
李士恩  申永坚 《人民珠江》2002,(2):23-26,32
概述改性混凝土垢发展情况,介绍纤维混凝土在国内外水工建筑物上的应用实例,提出钢纤维增强钢筋混凝土水工建筑结构强度计算方法。包括受弯构件正截面强度,斜截面抗剪强度的计算;重点介绍了网状钢纤维增强混凝土(FOC)在水工建筑物上的应用,包括在渡槽,闸门,小型拦河坝,轻型岸型等工程上的应用实例,T新梁正斜截面的强度计算,板材承载力计算的方法。  相似文献   
88.
研究结果表明 :水胶比、胶凝材料用量、钢纤维掺量、矿渣代水泥量对钢纤维砼强度影响显著。当矿渣取代水泥 10 %时 ,钢纤维砼强度最高。经试验选择出一个具有良好和易性和较高强度 (118MPa)的钢纤维砼配合比 ,为掺磨细矿渣的中含量超短异形钢纤维砼的设计和施工提供了试验依据  相似文献   
89.
As System on a Chip (SoC) testing faces new challenges, some new test architectures must be developed. This paper describes a Test Access Mechanism (TAM) named CAS-BUS that solves some of the new problems the test industry has to deal with. This TAM is scalable, flexible and dynamically reconfigurable. The CAS-BUS architecture is compatible with the IEEE P1500 standard proposal in its current state of development, and is controlled by Boundary Scan features.This basic CAS-BUS architecture has been extended with two independent variants. The first extension has been designed in order to manage SoC made up with both wrapped cores and non wrapped cores with Boundray Scan features. The second deals with a test pin expansion method in order to solve the I/O bandwidth problem. The proposed solution is based on a new compression/decompression mechanism which provides significant results in case of non correlated test patterns processing. This solution avoids TAM performance degradation.These test architectures are based on the CAS-BUS TAM and allow trade-offs to optimize both test time and area overhead. A tool-box environment is provided, in order to automatically generate the needed component to build the chosen SoC test architecture.  相似文献   
90.
李平  王汉功 《材料保护》2002,35(11):12-14
采用自行开发研制的超音速电弧喷设备,在45钢表面制成了钛铝合金复合涂层。并利用金相显微镜、X射线衍射仪、扫描电镜、电子探针,对涂层的成分、相结构、显微组织及其结合强度、显微硬度进行了研究。结果表明,利用超音速电弧喷涂设备,可以在45钢表面形成 度高、孔隙率低,结合强度较好和硬度高的Ti-Al合金涂层。  相似文献   
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