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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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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关键词：钢铁；金属加工；海军舰艇；磨具；合金

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Among underground coal miners, hearing loss remains one of the most common occupational illnesses. To address this problem, the U.S. National Institute for Occupational Safety and Health Office of Mine Safety and Health Research (NIOSH OMSHR) conducts research to reduce the noise emission of underground coal mining equipment, an example of which is the roof bolting machine. Field studies show that, on average, drilling noise is the loudest noise that roof bolting machine operators would be exposed to, and it contributes significantly to the operators noise exposure. OMSHR has determined that the drill steel and chuck radiate a significant amount of noise during drilling. OMSHR and the Corry Rubber Corporation (CRC) have developed a bit isolator that breaks the steel-to-steel link between the drill bit and drill steel and a chuck isolator that breaks the mechanical connection between the drill steel and the chuck. This effectively reduces the noise radiated by the drill steel and chuck and in turn reduces the noise exposure of roof bolter operators. This paper documents the evolution of the bit isolator and chuck isolator. Laboratory testing confirms that production bit and chuck isolators reduce the A-weighted sound level generated during drilling by 3.7 to 6.6 dB.

关键词：钢铁;煤炭开采;听力损失;演习;屋顶螺栓

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In 2005 Focus: HOPE began working on a Technical Area Task to investigate advanced manufacturing in the area of Direct Deposition of Metal (DDM) for the Tank and Automotive Command (TACOM). In 2006, the scope was expanded to include basic research areas of Direct Deposition of Metal applicable to repairing military equipment and Focus: HOPE demonstrated the feasibility of conducting repairs on military equipment using Direct Deposition of Metal (Work Directive WD-FH-0001). The study also demonstrated that there could be a potential cost saving by repairing parts using DDM over purchasing new replacement parts. The overall project was extended in 2010 to provide additional time to conduct additional certification testing of repaired components and demonstrate the effectiveness of the parts repaired using Direct Deposition of Metal. For the present project, extensive studies were conducted on the metallurgical properties and bonding between the newly deposited metal and the parent metal substrate. The findings, results and conclusions of this process certification testing are provided in this report.

关键词：金属；军钢铁；弯曲；腐蚀；沉积零件

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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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The paper presents changes of natural frequencies of industrial steel hall due to simplifications or changes of numerical model.Firstly,the natural frequencies were calculated for basic Variant A of the numerical model of the steel hall which consisted of the main frames,footings,roofpurlins and girts.In this Variant columns were fixed at bases,both purlins and girts were rigidlyconnected to main frames and designed as continuous beams.Then,in Variant B of the model columns were pinned at bases.Next,in Variant C different types of connections (semi-flexible joints)of roof purlins and girts with the main frame were implemented.Finally,in Variant D,soil-structure interaction was taken into consideration.The calculations of the dynamic characteristics of four abovementioned Variants of the numerical model of the hall showed that simplifications or changes of some details of the structure could result in significant errors in values of natural frequencies.

关键词：钢铁;固有频率;柔性接头;土结构相互作用

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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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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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Gravity structures play a prominent role today in North Sea oil development.These structures are not supported by piles as are most ocean structures but rather sit directly on the ocean bottom, and depend on their foundation geometries and large weights to resist severe environmental loadings.A number of structural and foundation configurations have been proposed; however,attention will be restricted in this discussion to a general configuration typical of the most prominent structures being constructed at present (1975). An example of a gravity structure is illustrated in Fig. 1. The structure foundation consists of a large caisson placed directly on the unprepared seabed surface.The deck is supported by large columns extending from the caisson.Various combinations of steel and reinforced concrete have been proposed, but the majority of structures are being constructed almost entirely of reinforced and prestressed concrete.

关键词：钢铁;重力式结构;石油;钢筋混凝土

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