The development length of reinforcements embedded into ultra-high performance concrete (UHPC) can be significantly shorter than the lengths normally associated with conventional concrete. Shortening the development length of prestressing strand can allow for a redesign of some structural systems, including spliced girder and continuous-for-live-load bridges. Ultra-high performance concrete (UHPC), when used in field-cast connections between prefabricated bridge elements, can create robust connections which emulate monolithic components. This study investigated the development length of 0.5 and 0.6 inch (12.7 and 15.2 mm) diameter untensioned prestressing strands embedded in steel fiber and PVA fiber reinforced UHPC. The volumetric fiber content was 2 percent. A novel tension test method allowed for replication of the tension-tension stress state that would occur when two strands are lap spliced within a connection between two linear elements. The results suggest that, for the steel fiber reinforced UHPC, the 0.5 inch (12.7 mm) diameter strands can be fully developed within 20 inches (0.51 m) and the 0.6 inch (15.2 mm) diameter strands can be fully developed in approximately 24 inches (0.61 m). The 0.5 inch (12.7 mm) diameter strands can be fully developed in the PVA fiber reinforced UHPC in approximately 36 inches (0.91 m).

关键词：高强度混凝土；钢绞线;桥梁；纤维增强混凝土

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Austenitization is a solid-phase transformation process accompanied by nucleation and nucleus growth controlled by long-range carbon diffusion. In our work, a method was developed for constructing spheroidite model structures in such a way that their different parameters (the size of ferrite grains, the average value of carbon concentration, the size of cementite spheroids) could be changed optionally. In addition, a nucleation model of free energy base was created by which the difference between the two different places of nucleation can be distinguished on the basis of their free energy. The effects of structure parameters, interface free energies and temperature on the nucleation rate of austenite were investigated by cellular automaton simulations.

关键词：奥氏体化；成核速率；球状渗碳体；元胞自动机

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Based on the shape detecting principle and the digital signal technology,a new shape meter was developed thorough theoretical analysis and industrial adjustment to develop the shape detecting roll,the shape signal processing method,the original signal compensation mechanism and so on.The shape meter has good performance and stability,which can effectively avoid the scratchof steel strip surface,accurately detect real online strip shape and provide accurate online shape datum for shape control system.It was applied in 1250 mm cold rolling mill,the actual industrial tests prove that the shape signal was stable and reliable,met the harsh condition and the online technical requirements,and could improve shape quality significantly.

关键词：板形仪；形状检测；形状控制；冷轧带钢

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The world shipbuilding industry since the beginning of the last century with flux cored wire material.Since the flux cored wire material use welding materials has developed into a more efficient submerged arc welding consumables and gas shielded welding welding consumables and can be more easily combined with automated welding and robot welding.So far,flux cored material applications favored.Gas shielded arc welding consumables mainly divided solid wire and flux cored wire,flux cored wire applications has increased year by year because of its practicality and efficiency.Flux cored wire as the main welding consumables trends,especially in the thick carbon steel plate welded favored.In order to understand the nature of the thick-walled components weld cracking and produces original Due on a thick-wailed T-joints butt weld ultrasonic flaw found Two crack metallographic and SEM fracture analysis.

关键词：药芯焊丝材料；气体保护；焊接裂纹

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In recent decades, bridge fires have become a major concern in the U.S. Fire hazard in bridges can result in significant economic and public losses. New construction of bridges often use Weathering Steel (also known as Corten Steel), which has a corrosion-retarding effect since the steel forms a protective rust layer on its surface under the influence of the weather. To date, no information exists on the high temperature mechanical properties of weathering steel. The objective of this work is to develop a database of mechanical properties of A588 weathering steel that has been exposed to high temperatures. These properties include the residual (after heating and cooling) stress-strain, fracture toughness, and surface hardness. The parameters that are investigated include temperature (800 degrees F, 1000 degrees F, 1200 degrees F, and 1500 degrees F), cooling methods (in air (CIA), and in water (CIW), representing fire-fighting effects), and material. Experiments are also done in a steady-state elevated temperature condition. A comparison is made between A588 weathering steel, used widely for bridges, and another material whose chemical composition and mechanical properties allows it to be classified by ASTM as both an older weathering steel (A242), a steel commonly used in building construction (A992), and also a non-weathering steel used for bridges (A709 Grade 50).

关键词：桥梁（构）筑物；化学成分；腐蚀；钢铁

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High hard armor steels are used on many tactical vehicles, such as the Stryker and the mine-resistant, ambush-protected vehicle. Although they provide good protection against armor-piercing threats, these steels corrode rapidly without the use of a good corrosion protective coating. Corrosion on military ground vehicles increases the infrared signal from the vehicle that the topcoat camouflage usually inhibits, making the vehicle more vulnerable to detection by the enemy. Stryker vehicles are prohibited from using hex-chrome and are currently coated without any pretreatment or conversion coating. The products demonstrated here will satisfy the hexavalent chrome prohibition while minimizing environmental impact and worker safety. This demonstration plan is designed to generate the data necessary for authorization and implementation decisions by appropriate authorities within the U.S. Department of Defense.

关键词：护甲；腐蚀；六价铬；高硬度装甲腐蚀

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Metal framing and glass is a broad category of exterior enclosure systems that includes storefront, window wall, and curtain wall systems. The metal framing components are primarily aluminum, but also include stainless steel, bronze, or other architectural quality metals. Infill supported by or within the framing includes transparent or opaque materials. Transparent infill materials include insulating, laminated, or monolithic glass; polycarbonates; and thermoplastics. Opaque infill materials include architectural metals such as aluminum, stainless steel, or bronze; natural stone; fiber reinforced panels; terra cotta; or louvers.

关键词：金属框架；不透明填充材料；钢铁

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Iron is produced by the reduction of iron ore and other iron oxides as a precursor to steel and by remelting of metallic stock to produce a family of iron-based alloys (cast irons) for industrial use. More than 1 billion metric tons of iron is produced annually by reduction processes.1 Blast furnaces account for more than 90% of iron reduction with the rest accomplished through direct reduction or "alternate ironmaking" processes. Cupola furnaces, rotary furnaces, and induction furnaces are the primary units for cast iron re-melting. In 2009, the cast iron production of the main industrialized countries was 58.6 million metric tons. The role of oxygen combustion in reduction processes is described in Sections 21.2 and 21.3, and in re-melting processes in Section 21.4.

关键词：铁矿石；氧化铁；钢铁

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Directly-generated compressive residual stress has become a widely used surface modification technique. Intentional residual stress in solid materials can be produced by different surface compression methods. It is well known how residual stress field is influenced by the parameters of the shoot peening but only few articles address the phenomenon about the evolution of the stress during the operation of the machine component. The literature on residual stress decrease caused by fatigue load is scarce and the kinetics of this mechanism is not yet investigated. The present work reports on the examination of the effect of the fatigue load on compressive residual stress strengthened specimens. Investigations have been conducted at three stress levels. Residual stress data have been measured by X ray diffraction method before fatigue load and measurements have been repeated after defined fatigue cycles.

关键词：残余应力；X射线衍射；疲劳

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Small batches of two oxide powders falling in the particle size range of about 30-230 μm were received from industrial sources and were electroless nickel (EN) coated in order to prepare properly modified reinforcing particles for further laboratory experiments with the Laser Melt Injection (LMI) technique to produce particle reinforced steel composite surface layers. The partially calcined alumina (Al2O3) as well as the hydrothermally recycled crystalline iron(Ⅲ) oxide precipitate were characterized first to check their exact size ranges, specific surface areas and major chemical contaminants so that the best possible EN plating technique would be selected and applied. It was revealed soon that the sensitization and activation pre-treatment steps could not be omitted and after their proper adjustment, also the composition and pH of a relatively commonly used hypophosphite reducing type bath had to be modified to the given purpose. Eventually a slightly alkaline EN bath was successfully prepared with which both industrial oxide powders surface could be nickel coated soundly, which final result was demonstrated also by several metallographic testing techniques showing the microstructure of the quite evenly and fully coated oxide particles.

关键词：化学镀镍；氧化铝粉；氧化铁粉末

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