Fracture toughness and fatigue properties of pipeline steels play a critical role in developing advanced high-pressure hydrogen infrastructure for alternative fuel pipelines program. The reliability of structure components, particularly resistance to damage and failure in the intended service environment, is highly dependent on the selected materials. An effective surveillance program is also necessary to monitor the material degradation during the course of service. Steels have been proven to be desirable for hydrogen infrastructure. However, hydrogen embrittlement is an important factor that limits steel performance under high-pressure hydrogen conditions. In order to reach the above goal, we have proposed an innovative technology, based on spiral notch torsion test (SNTT) methodology, to effectively investigate the material performance of X52 pipeline steel. The SNTT approach was successfully demonstrated and extended to X52 steels during the performance period. In addition to single notch front geometry, the crack growth behavior of the SNTT process has been effectively established using an integrated experimental, numerical and analytical approach. The results indicate that the proposed protocol not only provides significant advance in understanding the compliance evolution of the SNTT specimen, but also can be readily utilized to assist future development of hydrogen infrastructures. In FY2011, an extensive study was performed to characterize the fracture toughness degradation of AISI 4340 high-strength steel exposed to high-pressure hydrogen using in situ spiral notch torsion tests. This effort included equipment setup and calibration, sample design and fabrication, finite element simulation of the specimen fracture, and fractographic characterization using advanced microscopic techniques. The detailed description of the results is summarized in by Wang (Wang 2011).

关键词：管道；钢；断裂强度；缺口冲击试验

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The Commission instituted these reviews on June 3, 2013 (78 FR 33108,) and determined on September 6, 2013 that it would conduct expedited reviews (78 FR 59371, September 26, 2013).

关键词：钢铁；进口；碳素钢；钢管；焊件

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Severe localized corrosion of a 316 stainless steel autoclave occurred during investigating Type H Portland cement stability in 0.16 M CaCl(sub 2) + 0.02 M MgCl(sub 2) + 0.82 M NaCl brine in contact with supercritical CO(sub 2) containing 4O(sub 2). The system operated at 85 C and pressure of 29 MPa. However, no corrosion was observed in the same type of autoclave being exposed to the same environment, containing Type H Portland cement cylindrical samples, also operating at pressure of 29 MPa but at 50 C. The operation time for the 85 C autoclave was 53 days (1272 hours) while that for the 50 C autoclave was 66 days (1584 hours). Debris were collected from the base of both autoclaves and analyzed by X-ray diffraction (XRD). Corrosion products were only found in the debris from the 85 C autoclave. The cement samples were analyzed before and after the exposure by X-ray florescence (XRF) methods. Optical microscopy was used to estimate an extent of the 316 stainless steel corrosion degradation.

关键词：腐蚀;不锈钢;高压蒸汽灭菌器;盐水

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There are specific components in the SRS Tritium Facilities that are required to introduce as few chemical impurities (such as protium and methane) as possible into the process gas. Two such components are the inlet systems for the mass spectroscopy facilities and hydrogen isotope mix standard containers. Two vendors now passivate stainless steel components for these systems, and both are relatively small businesses whose future viability can be questioned, which creates the need for new sources. Stainless steel containers were designed to evaluate alternate surface treatment vendors for tritium storage and handling for these high purity tritium systems. Five vendors applied their own 'best' surface treatments to two containers each - one was a current vendor, another was a chemical vapor deposited silicon coating, and the other three were electropolishing and chemical cleaning vendors. Pure tritium gas was introduced into all ten containers and the composition was monitored over time. The only observed impurities in the gas were some HT, less CT(sub 4), and very small amounts of T(sub 2)O in all cases. The currently used vendor treated containers contained the least impurities. The chemical vapor deposited silicon treatment resulted in the highest impurity levels. Sampling one set of containers after about one month of tritium exposure revealed the impurity level to be nearly the same as that after more than a year of exposure - this result suggests that cleaning new stainless steel components by tritium gas contact for about a month may be a worthy operation.

关键词：不锈钢;甲烷;质谱;氚;清洗

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Continuous cooling transformation (CCT) curves of deformed austenite (A) of Nb-Ti microalloying high strength steel were measured using Gleeble-3800 thermo-mechanical simulator,and corresponding transformation and structure were analyzed,and the effects of cooling rate on the tested steel's mechanical property were studied.The resultes showed that the Ar3 transformation point decreased with increasing cooling rate after hot-rolling.The morphology of ferrite (F) grains changed from polygonal to lath,and the pearlite (P) colonies became more fine with increasing cooling rate.The quantity of ferrite and pearlite decreased,and the quantity of bainite (B) and martensite (M) increased.Then the hardness of Nb-Ti micro-alloyed steel is increased along with the increasing cooling rate,which may owing to the reasons that the hardness of ferrite and pearlite is far smaller than that of bainite and martensite,and the grain refinement causes the hardness increasing.

关键词：钢铁；铌钛微合金化钢；CCT曲线；相变

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The goal of the proposed project is to further develop and market advanced 70-ksi-yield strength super-tough steel (designated as NUCu60ST in the text) for use in tank cars transporting cryogenic liquids, like chlorine, for example. Fracture of these tanks resulted in a number of industrial accidents. One in 2005 in Graniteville, South Carolina led to nine deaths and at least 250 injuries. This is a joint project with Union Tank Car Company (UTLX). Developed and investigated at Northwestern University by prior funding from ITI and CCITT, the super-tough cyrogenic steel was included into the 'Next-Generation Rail Tank Car Project', an innovative joint initiative of the three companies (Dow, Union Pacific and UTLX), Association of American Railroads (AAR), and US and Canada Departments of Transportation focused on the design and implementation of a next-generation rail tank car with enhanced ability to safely transport hazardous chemicals.

关键词：钢;坦克车;危险品运输;低温;氯

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This paper focused on the uniaxial ultimate-bearing-capacity of large size concrete filled steel tubular (CFST) columns. Two aspects were investigated experimentally. To verify the feasibility of similarity principles for large size components, a series of uniaxial compressive experiments were conducted using different scaled specimens, the prototype of which is a CFST arch rib in an authentic arch bridge. Meanwhile, two specimens with same scale were tested axially and eccentrically to investigate the difference of bearing capacity resulted from the pierced-column. The experimental results show that the size effect on the bearing capacity of the rib is so insignificant that the scaled specimen can be used to obtain the maximum capacity of the full-scale component. The inserted steel tubes in the middle of the column cause the reduction of its capacity and the reduction factor from axial loading is bigger than that from bias load. Moreover, the eccentricity reduces the effect of piercing on the capacity of CFST column.

关键词：钢管混凝土（CFST）柱;单轴压缩;承载力;大口径柱

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关键词：钢铁；金属加工；海军舰艇；磨具；合金

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On the basis of the record developed in the subject investigations, the UnitedStates International Trade Commission determines, pursuant to section 735(b) of the Tariff Act of 1930 (19 U.S.C. Section 1673d(b)) (the Act), that an industry in the United States is materially injured by reason of imports from Japan and South Africa of certain small diameter seamless carbon and alloy steel standard, line, and pressure pipe (small diameter pipe), provided for in subheadings 7304.10.10, 7304.10.50, 7304.31.30, 7304.31.60, 7304.39.00, 7304.51.50, 7304.59.60, and 7304.59.80 of the Harmonized Tariff Schedule of the United States, that have been found by the Department of Commerce to be sold in the United States at less than fair value (LTFV). The Commission made negative determinations concerning critical circumstances. The Commission also determines that an industry in the United States is materially injured by reason of imports from Japan of certain large diameter seamless carbon and alloy steel standard, line, and pressure pipe (large diameter pipe), provided for in subheadings 7304.10.10, 7304.10.50, 7304.31.60, 7304.39.00, 7304.51.50, 7304.59.60, and 7304.59.80 of the Harmonized Tariff Schedule of the United States, that have been found by the Department of Commerce to be sold in the United States at LTFV.

关键词：钢铁；管道；进口；南非

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Laser welding and post weld laser treatment of modified 9Cr-1MoVNb steels (Grade P91) were performed in this preliminary study to investigate the feasibility of using laser welding process as a potential alternative to arc welding methods for solving the Type IV cracking problem in P91 steel welds. The mechanical and metallurgical testing of the pulsed Nd:YAG laser-welded samples shows the following conclusions: (1) both bead-on-plate and circumferential butt welds made by a pulsed Nd:YAG laser show good welds that are free of microcracks and porosity. The narrow heat affected zone has a homogeneous grain structure without conventional soft hardness zone where the Type IV cracking occurs in conventional arc welds. (2) The laser weld tests also show that the same laser welder has the potential to be used as a multi-function tool for weld surface remelting, glazing or post weld tempering to reduce the weld surface defects and to increase the cracking resistance and toughness of the welds. (3) The Vicker hardness of laser welds in the weld and heat affected zone was 420-500 HV with peak hardness in the HAZ compared to 240 HV of base metal. Post weld laser treatment was able to slightly reduce the peak hardness and smooth the hardness profile, but failed to bring the hardness down to below 300 HV due to insufficient time at temperature and too fast cooling rate after the time. Though optimal hardness of weld made by laser is to be determined for best weld strength, methods to achieve the post weld laser treatment temperature, time at the temperature and slow cooling rate need to be developed. (4) Mechanical testing of the laser weld and post weld laser treated samples need to be performed to evaluate the effects of laser post treatments such as surface remelting, glazing, re-hardening, or tempering on the strength of the welds.

关键词：电弧焊接；激光焊接；钢；焊接接头

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