钢筋窄间隙焊及其工程应用

本文介绍了一种钢筋连接新方法──钢筋窄间隙焊，并对其接头的力学性能和微观组织进行了研究。在大型水电站工程的应用表明，该方法特别适用于基建钢筋混凝土工程中的工期紧、粗钢筋密集、施工强度大、条件差、工程质量要求高的施工作业面。     

钢筋混凝土埋入式牺牲阳极阴极保护试验研究

目的 提高现有牺牲阳极阴极保护技术的效果，采用活性阳极包覆砂浆，制备一种埋入式牺牲阳极，并研究其应用特性。方法 采用二电极法测试阳极包覆砂浆的电阻率，通过加速试验、SEM-EDS分析锌腐蚀产物的迁移状况，采取自耦合试验测定埋入式牺牲阳极下钢筋的电位等参数;在此基础上，研究埋入式牺牲阳极的特性及其阴极保护范围。结果 活性阳极包覆砂浆的电阻率仅为18.48 Ω.m。闭路电位、瞬间断电电位测试显示钢筋的稳定保护电位为−400~ −440 mV，断电电位为−218 mV，满足NACE标准对衰减电位的最低要求(200 mV)。电流密度结果表明，埋入式阳极可提供的保护电流密度为6.1~7.7 mA/m²，符合EN 12696要求。通过网格法测量的结果显示，在钢筋密度比为0.20，以及高腐蚀环境条件下，埋入式牺牲阳极的最大有效保护距离可达到700 mm。SEM-EDS分析结果表明，锌阳极发生反应，生成了可溶性锌酸盐(ZnO2²⁻)，且会由锌阳极表面向砂浆内部迁移，最终逐渐分散到砂浆孔隙中，可有效解决因锌阳极表面腐蚀产物聚集而影响活性的问题，并消除腐蚀产物体积增大造成的膨胀应力。工程应用结果表明，各测试点钢筋的保护电位均负于−400 mV，满足保护要求。结论 埋入式牺牲阳极对钢筋有较好的保护效果，能够保持电位、电流输出稳定，不会影响阳极的活性，也不会给混凝土结构带来膨胀应力。     

双相20钢在钢筋冷压套筒连接上的应用

热轧20钢管在汉相区加热、水淬及空冷后可获得马民体加铁素体的双相组织，该双相20钢制作的套筒用以冷压连接IV级钢筋，在拉伸试验过程中套筒与钢筋之间不出现滑脱现象（相对滑动），断裂均在钢筋本体，力学性能均能满足日本（钢筋接头性能评定标准）的SA级指标要求。     

顶吹法从密闭鼓风炉渣中回收锌

为了从密闭鼓炉渣中的回收锌，Ｓｉｒｏ熔炼顶吹法系统已经通过实验室试验和工业试验，对气体注入速率，加煤方法和锌烟化速率的温度等过程变量的影响在试验室中进行了研究，发现锌速率取于所有这些变量，当渣中锌的含量在１．５％以上时，从渣中除锌的速率与锌的含量无关，但在１．５％以下时，除锌速率与渣中的锌含量成正比。     

加标Gr400W可焊钢筋的研制开发与生产

为参与国际市场竞争 ,济钢对加标Gr40 0W钢筋进行了开发。通过对该钢筋的质量特性分析 ,制定了加标钢筋的化学成分、孔型设计方案和生产工艺。生产实践证明 ,该产品开发获得成功 ,产品质量达到标准要求     

锌加涂料在水工钢结构防腐蚀中的应用

介绍了锌加涂料作为底漆与配套涂料相组合的防腐蚀方案、施工工艺、质量控制和保护效果。在南水北调东线刘山泵站工程上的应用表明,该材料施工简单、安全高效、造价低、保护效果好,适合于水工金属结构的腐蚀防护。     

压水堆条件下锌对690合金表面氧化膜的影响

模拟压水堆一回路加锌水环境,对镍基690合金在加锌浓度为10μg/kg的320℃,15.20 MPa溶液中进行了1000 h的腐蚀试验。采用XPS深度分析法对试样氧化膜进行分析。结果表明,锌能有效地降低690合金的均匀腐蚀速率,加锌后氧化膜形貌和成分都有了明显改变,氧化膜厚度变薄。     

金鼎锌业7月29日产出第一批锌锭

来自四川宏达的信息，四川宏达控股的云南金鼎锌业有限公司10万吨电解锌项目经过一年多的施工已经在7月29日生产出第一批锌锭。     

低压冷喷涂Cu-Zn复合涂层耐蚀性能的研究

本文使用低压冷喷涂技术,分别在45#钢基体与45#钢加镀铬层基体上制备铜锌涂层试样。通过静态浸泡与铜加速醋酸盐雾腐蚀试验（CASS）对涂层和涂层加镀铬层试样的腐蚀性能进行研究;采用SEM、XPS对腐蚀前后涂层与镀铬层的微观形貌与元素进行表征。结果表明：静态腐蚀过程中,铜锌涂层的耐腐蚀性优于铜锌涂层加镀铬层;CASS实验中,随着原始粉体中锌含量的增加,涂层试样与涂层加镀铬层试样的耐腐蚀性能提高,当铜锌比为6:4时,对应涂层试样、涂层加镀铬层试样与纯镀铬层的耐腐性能达到六级。铜锌涂层在腐蚀液中由于电化学腐蚀及氯化作用,导致铜锌均发生了腐蚀,其腐蚀产物主要为Zn(OH)2、Cu2O与CuCl2。铜锌涂层加镀铬层试样在腐蚀过程中,锌的腐蚀在一定成上可以起到减缓镀铬层腐蚀的作用,这种减缓的作用与镀铬层上析出的铜膜共同保护镀铬层,增强其耐腐蚀性能。     

冷却剂加锌对核电结构材料腐蚀行为的影响

选用与压水堆(PWR)核电站一回路冷却剂接触面积最大的结构材料690合金和316LN锻造不锈钢为研究对象,在模拟PWR一回路水化学环境下,采用静态高压釜浸泡方法和高温电化学方法研究冷却剂中加锌对这2种结构材料腐蚀行为的影响。研究发现,冷却剂加锌能明显抑制材料的均匀腐蚀速率和腐蚀产物释放速率。高温水中,以醋酸锌形式加锌,锌离子浓度为(10～50)ng/g时,能有效抑制腐蚀速率和腐蚀产物释放速率,加锌50ng/g以上,加锌浓度对腐蚀速率和腐蚀产物释放速率的影响趋于稳定。     

水性硅酸盐溶胶型涂料对钢筋混凝土耐久性的影响

分析了钢筋混凝土腐蚀破坏的主要原因是钢筋腐蚀导致的混凝土胀裂.为保护钢筋混凝土研制了一种水性硅酸盐溶胶型涂料并研究了该涂料对混凝土内置网筋的保护作用及经涂料涂覆的混凝土氯离子渗透性和高压渗水性能.结果表明,涂履水性硅酸盐溶胶型涂料可明显提高与改善混凝土的耐久性.     

水环境混凝土中钢筋腐蚀及其研究的现状与趋势

本文主要对混凝土中钢筋腐蚀的机理及其测量方法的研究现状进行论述。讨论了钢筋腐蚀与混凝土碳化这两种引起混凝土构件破坏的主要因素、基本机理与特征,简要介绍了各种环境因素,尤其是氯离子与碳化对钢筋腐蚀的影响,介绍了几种钢筋腐蚀的电化学原位快速无损检测方法,分析目前钢筋腐蚀研究存在的问题并提出今后发展方向。     

棒线混合车间安装中的几项技改

本文介绍了棒线混合车间建造中的几项技术改造并给出了相关的简图,同时简要叙述了它的创新点和实用性,并针对生产实践给出了改进措施.     

Effect of Alloying Elements on Tensile Properties, Microstructure, and Corrosion Resistance of Reinforcing Bar Steel

The effect of copper, phosphorus, and chromium present in a semikilled reinforcing bar steel produced by in-line quenching [thermomechanical treatment (TMT)] process on the tensile properties, microstructure, and corrosion resistance of steel in simulated chloride environment has been investigated. The results have been compared with that of a semikilled C-Mn reinforcing bar steel without these alloying elements produced by the same process route. Though the amount of phosphorus (0.11 wt.%) was higher than that specified by ASTM A 706 standard, the Cu-P-Cr steel exhibited a composite microstructure, and good balance of yield stress, tensile stress, elongation, and ultimate tensile to yield stress ratio. Two conventional test methods, namely, the salt fog, and potentiodynamic polarization tests, were used for the corrosion test. The rust formed on Cu-P-Cr steel was adherent, and was of multiple colors, while the corrosion products formed on the C-Mn steel were weakly adherent and relatively darker blue. Also, the free corrosion potential of the Cu-P-Cr steel was nobler, and the corrosion current was markedly lower than that of a C-Mn rebar. The Cu-P-Cr steel did not develop any pits/deep grooves on its surface even after the prolonged exposure to salt fog. The improved corrosion resistance of the Cu-P-Cr steel has been attributed to the presence of copper, phosphorus, and small amount of chromium in the dense, adherent rust layer on the surface of reinforcing steel bar. A schematic mechanism of charge transfer has been proposed to explain the improved corrosion resistance of the Cu-P-Cr alloyed TMT rebar.     

混凝土结构中NO_2~-的不均匀性对钢筋宏电池腐蚀行为的影响

基于宏电池腐蚀理论,将阴极区钢筋和阳极区钢筋分别浇筑成两个独立的砂浆试块,并用导线将其连接成循环电路,通过断开和连接电路来控制钢筋的微电池腐蚀和宏电池腐蚀,再将不同浓度的NO_2~-溶液分别添加到阴极试块和阳极试块中以模拟其渗透过程,通过比较NO_2~-作用前后阴阳极钢筋之间宏电池腐蚀电流的大小,来评价阴阳极钢筋表面NO_2~-的不均匀性对钢筋宏电池腐蚀行为的影响。结果表明:当NO_2~-作用于处于腐蚀状态的阳极钢筋时,能够增加阳极钢筋的极化阻抗,减少阴阳极钢筋间的宏电池腐蚀电位差,降低宏电池腐蚀电流,从而有效抑制宏电池腐蚀;当NO_2~-主要作用于处于腐蚀状态的阴极钢筋时,阴阳极钢筋间的宏电池电位差的增大易使宏电池腐蚀电流增加,存在加速钢筋宏电池腐蚀的危险。     

Long term assessment of a hybrid electrochemical treatment

Monitoring the performance of systems installed to protect against/halt the corrosion of reinforcing steel in concrete is essential in ensuring that the reinforcing bar (rebar) is adequately protected and remains in a non‐corroding state. A chloride contaminated concrete test block containing a hybrid anode system has been periodically monitored over the past 4.5 years to assess the anode current output and thus, the protection offered to the steel. De‐polarisation and impedance analysis data have been acquired to calculate steel corrosion rates. Both tests indicated that the steel was passive in the concrete environment and that the anode was able to protect all of the embedded steel despite the difficult geometry of the sample. It was also found that after 2 years it was still possible to drive a high current from the installed anode.     

Study of aging and embrittlement of microalloyed steel bars

The aging of hooks, anchors, and other bent reinforcing steel bars in concrete structures are considered in modern international standards. Rebend test procedures have been designed in order to predict the aging embrittlement susceptibility by submerging bent reinforcing bar specimens in boiling water. Subsequently the bars are rebent or straightened in order to determine the loss of ductility or embrittlement of the aged material. The present work considers the influence of carbon, sulfur, and niobium on the performance of reinforcing bars in rebend tests of 300 heats of microalloyed steel bars with a variety of compositions. The microstructural evidence and the statistical results clearly indicate the strong influence of carbon and sulfur on rebend failure, while niobium-rich precipitates contribute to the hardening of the ferrite grains during aging.     

钢材拉伸试验中的不确定度评定

根据实验室认可的一般要求,简要介绍了测量不确定度的基本概念。对测量不确定度的评定过程和基本方法进行系统的论述。并通过对钢筋的拉伸试验,展示了钢材拉伸试验中的不确定度评定的全过程。     

Damage analysis and cracking model of reinforced concrete structures with rebar corrosion

The damage of concrete cover in reinforced concrete structures induced by reinforcing steel corrosion is investigated in this study. The damage process of the concrete cover can be divided into two distinct stages: the non-cracking stage and the partial cracking stage. An analytical model based on damage mechanics and elastic mechanics is developed to predict the concrete cracking due to steel corrosion. Based on this model, the expansive pressure and the radial loss of steel bar are discussed. Parametric studies are carried out to examine the effects of the correlative factors on the expansive pressure and the steel loss.     

混凝土中氯离子的预防及处理

氯离子对混凝土结构的腐蚀已引起广泛重视，本文就目前对混凝土防腐蚀所采取的隔离、修补、钢筋保护、电化学除盐及阴极保护法的具体应用作了简要论述。