This investigation was prompted by results of a qualification test of a mechanism to be used for the James Webb Space Telescope. Post-test inspections of the qualification test article revealed some loose wear debris and wear of the steel rollers and the mating Ti6Al4V surfaces. An engineering assessment of the design and observations from the tested qualification unit suggested that roller misalignment was a controlling factor. The wear phenomena were investigated using dedicated laboratory experiments. Tests were done using a vacuum roller rig for a range of roller misalignment angles. The wear in these tests was mainly adhesive wear. The measured wear rates were highly correlated to the misalignment angle. For all tests with some roller misalignment, the steel rollers lost mass while the titanium rollers gained mass indicating strong adhesion of the steel with the titanium alloy. Inspection of the rollers revealed that the adhesive wear was a two-way process as titanium alloy was found on the steel rollers and vice versa. The qualification test unit made use of 440F steel rollers in the annealed condition. Both annealed 440F steel rollers and hardened 440C rollers were tested in the vacuum roller rig to investigate possibility to reduce wear rates and the risk of loose debris formation. The 440F and 440C rollers had differing wear behaviors with significantly lesser wear rates for the 440C. For the test condition of zero roller misalignment, the adhesive wear rates were very low, but still some loose debris was formed

关键词：合金;滚筒；钢；钛合金；钒合金

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John F. Kennedy Space Center (KSC) has equipment and processes which require the passivation of stainless steel. The standard practice for passivation uses nitric acid. While nitric acid exhibits excellent performance, there are a number of environmental and safety issues: nitrogen oxide (NOx) emissions are considered greenhouse gases, NOx are volatile organic compounds that contribute to smog, NOx increase nitrogen loading (oxygen depletion) in bodies of water, nitric acid can remove beneficial heavy metals (nickel, chromium, etc) from surfaces, and worker safety issues. The longtime military specification for passivation of stainless steel was Federal Specification QQ-P-35 (Passivation Treatments for Corrosion-resistant Steel), but that has been cancelled in favor of American Society for Testing and Materials (ASTM) A 967 (Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts) and Aerospace Material Specifications (AMS) 2700 (Passivation Treatments for Corrosion-resistant Steel). Both of the new specifications allow for the use of citric acid in place of nitric acid. In addition, KSC also uses NASA-STD-5005 (Standard for the Design and Fabrication of Ground Support Equipment) and ASTM A 380 (Standard Practice for Cleaning, Descaling, and Passivation of Stainless Steel Parts, Equipment, and Systems). The primary objective of this effort is to demonstrate and validate citric acid as an alternative to nitric acid for the passivation of stainless steels. Citric acid offers a variety of benefits: it is naturally occurring and biodegradable; upon disposal, it is rarely classified as a hazardous waste; it does not remove beneficial heavy metals from surfaces; and there are no toxic fumes created during the passivation process. This project is follow-on to United Space Alliance (USA) work to optimize the parameters for the use of citric acid and verify effectiveness. USA evaluated the following parameters during their effort: concentration, temperature, and dwell time. This project will use the results from that testing to determine what process parameters will be used in the preparation of test coupons. This Test Protocol contains the critical requirements and tests necessary to qualify citric acid as an alternative to nitric acid for use at KSC. These tests were derived from engineering, performance, and operational impact (supportability) requirements defined by KSC participants. A Test Report will document the results of the testing as well as any test modifications made during the execution of the testing. The Test Report will be made available as a reference for future pollution prevention endeavors by other NASA centers, the Department of Defense, and commercial users to minimize duplication of effort. Users of this Test Protocol should check the project's Test Report for additional test details or minor modifications that may have been necessary in the execution of the testing. The technical stakeholders will have agreed upon test procedures modifications documented in the Test Report.

关键词：柠檬酸;耐腐蚀;硝酸;被动;污染控制;不锈钢

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4Cr5MoSiV1 steel,a widely used for hot work mould,contains Cr,Mo,V alloying elements that easily form carbides.The Micro-area chemical composition,microstructure,impact toughness and thermal fatigue behavior of 4Cr5MoSiV1 and 4Cr5MoSiV1H steels were investigated,the latter was carried on high temperature homogenizing and solution based on the former.The results showed that bulk eutectic carbides and elements segregation contained in the 4Cr5MoSiV1 steel reduced the impact toughness.But the impact toughness of the core of the mould steel block and thermal fatigue property of 4Cr5MoSiV1H steel were improved because the elements segregation and eutectic carbides was eliminated through the high temperature homogenizing and solution.

关键词：钢；高温均匀化；元素偏析；力学性能

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关键词：钢铁；形状记忆合金；执行器；二元合金

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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：钢铁；冷轧带钢；冷轧机；板形仪

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Fine balance between active galvanic and passive barrier corrosion protection by zinc-rich hybrid paints is explored depending on the absolute and relative amounts of the electrically semi-conducting particles, viz. polypyrrole (PPy) modified alumina hydrate and multi-walled carbon nanotubes (MWCNTs) and the zinc pigments. The former was varied between 3.21 and 1.75 wt., the latter was altered from 70 to 80 wt.in the primers. The coating with less zinc indicated firm and stable barrier nature in a 254 h immersion test whereas the primer with greater zinc content afforded superior galvanic corrosion prevention in salt-mist test over 142 days. Different nature of the coatings are expounded on the basis of structure and 3D arrangement of the nano-size inhibitor particles in the epoxy vehicle besides interpreted considering varied grain contents caused changing electrical percolation and electrolytic conductivity of the primers.

关键词：钢铁;纳米管;低碳钢;富锌涂料

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Oak Ridge National Laboratory has been investigating a new class of Fe-based amorphous material stemming from a DARPA, Defense Advanced Research Projects Agency initiative in structural amorphous metals. Further engineering of the original SAM materials such as chemistry modifications and manufacturing processes, has led to the development of a class of Fe based amorphous materials that upon processing, devitrify into a nearly homogeneous distribution of nano sized complex metal carbides and borides. The powder material is produced through the gas atomization process and subsequently utilized by several methods; laser fusing as a coating to existing components or bulk consolidated into new components through various powder metallurgy techniques (vacuum hot pressing, Dynaforge, and hot isostatic pressing). The unique fine scale distribution of microstructural features yields a material with high hardness and wear resistance compared to material produced through conventional processing techniques such as casting while maintaining adequate fracture toughness. Several compositions have been examined including those specifically designed for high hardness and wear resistance and a composition specifically tailored to devitrify into an austenitic matrix (similar to a stainless steel) which poses improved corrosion behavior.

关键词：钢铁；不锈钢；粉末冶金；非晶材料

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This program was undertaken to develop a microalloy-modified grade of standard carburizing steel that can successfully exploit the high temperature carburizing capabilities of current commercial low pressure (i.e. 'vacuum') carburizing systems. Such steels can lower the amount of energy required for commercial carburizing operations by reducing the time required for deep-case carburizing operations. The specific technical objective of the work was to demonstrate a carburizing steel composition capable of maintaining a prior austenite grain size no larger than ASTM grain size number 5 after exposure to simulated carburizing conditions of 1050 C for 8 hr. Such thermal exposure should be adequate for producing carburized case depths up to about 2 mm. Such carburizing steels are expected to be attractive for use across a wide range of industries, including the petroleum, chemical, forest products, automotive, mining and industrial equipment industries. They have potential for reducing energy usage during low pressure carburizing by more than 25, as well as reducing cycle times and process costs substantially. They also have potential for reducing greenhouse gas emissions from existing low pressure carburizing furnaces by more than 25. High temperature carburizing can be done in most modern low pressure carburizing systems with no additional capital investment. Accordingly, implementing this technology on carburizing furnaces will provide a return on investment significantly greater than 10. If disseminated throughout the domestic carburizing community, the technology has potential for saving on the order of 23 to 34 trillion BTU/year in industrial energy usage. Under the program, two compositions of microalloyed, coarsening-resistant low alloy carburizing steels were developed, produced and evaluated. After vacuum annealing at 1050oC for 8 hrs and high pressure gas quenching, both steels exhibited a prior austenite ASTM grain size number of 5.0 or finer. For comparison, a control alloy of similar composition but without the microalloy additions exhibited a duplex prior austenite grain size with grains ranging from ASTM grain size 3 down to ASTM grain size 1 after similar processing and thermal exposure. These results confirm the potential for using microalloy additions of Ti, B, Nb, Al, rare earths and/or N for austenite grain size control in Cr-Mo (i.e. 4000-series) low alloy carburizing steels. They also demonstrate that these microalloy additions will not compromise the processability of the steel; all three materials produced under the program could be hot worked readily using normal steel processing protocols. To fully realize the technical and commercial potential of these steels, there is a need to continue development work using larger-scale heats. These larger-scale heats are needed to provide adequate material for fatigue testing of quenched and tempered alloys, to conduct more complete investigations of potential alloy chemistries and to provide additional material for processing studies.

关键词：钢;渗碳;算法;合金

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On the basis of the theoretical study and application of ordinary steel-encased concrete composite beam,this paper will focus on a new high-strength steel-encased concrete composite beam,and mainly studies high-performance steel Q420 and Q460,as well as high-strength concrete C60 and C80.Besides,an experimental study of 5 simply-supported beams is made,and the load-deflection curves of new SCCB are analyzed.The calculation formula of load which changes with depth of section and bending strength of the cross section is also analyzed.It is suggested that the calculated results announced should be identical with the experimental results.

关键词：高强度钢-混凝土组合梁（SCCB下同）;高性能钢，高强度混凝土;抗弯承载力

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Replacement of the steel grating deck on the lift span of the Morrison Bridge in Portland, OR, will utilize glass fiber reinforced polymer (FRP) panels to address ongoing maintenance issues of the deteriorated existing deck, improve driver safety and introduce bridge water runoff treatment. This report outlines the testing methods and results of an experimental program aimed primarily at evaluating a new open cell deck. While most FRP panels are connected via shear studs that are grouted within isolated pockets, the panels in this case were bolted directly to the steel stringers. Two different FRP deck options were evaluated for comparison: one with open cells and the other with more conventional closed box extrusions. The objective was to evaluate the strength of the FRP to steel stringer connection with individual bolt connection tests, the strength and fatigue resistance of the FRP decks themselves, and the relative lateral stiffness contribution of the panels. Additional related tests were also included to complement the research effort such as the inclusion of tests on a closed box deck removed from the Broadway Bridge in Portland, OR, and strength tests of a retrofit attachment option of FRP deck to stringer using bolted clamps.

关键词：钢铁；桥面；纤维增强；玻璃纤维增强复合材料

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