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Acta Metallurgica Sinica(English Letters) 2011年第3期24卷 235-242页

作者： Limin SHEN jianming gong Yong JIANG Luyang GENG College of Mechanical and Power Engineering Nanjing University of Technology Nanjing 210009 China

Cr25Ni35Nb and Cr35Ni45Nb alloys are usually used in the ethylene cracking furnaces. However, premature failure of furnace tubes often occurs ahead of design life due to elevated temperature exposure conditions （1050-1100 ℃） and aggressive service environment. Effects of exposure temperature and time on microstructure and mechanical properties of Cr25Ni35Nb and Cr35Ni45Nb steel at aging temperature （1200 ℃） with various exposure time were simulated different service times at 1050 ℃. Change of mechanical properties at room temperature and elevated temperature （900 ℃） of the aged Cr25Ni35Nb and Cr35Ni45Nb steel were investigated. Under exposure at 1200 ℃, ultimate tensile and yield strength, elongation of Cr35Ni45Nb steel increase initially and then decrease, however, strength and ductility of Cr25Ni35Nb steel decrease with aging time increasing. Large amount of fine secondary carbide particles precipitated and dispersed in matrix of Cr35Ni45Nb steel, which increased strength and ductility for dispersion strengthening. However, the effect of the dispersion strengthening is weakened by needle-like secondary carbides. Strength and ductility decreased with fine secondary carbide particles growing. For Cr25Ni35Nb steel, few fine secondary carbide particles precipitated and dispersed in the matrix, and needle-like secondary carbides generated in the matrix, which causes strength and ductility decreased with aging time increasing.

关键词： Aging treatment Furnace tube steel Mechanical property Microstructure Cr25Ni35Nb Cr35Ni45Nb

Damage prediction of HP40Nb steel with coupled creep and carburization based on the continuum damage mechanics

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Acta Metallurgica Sinica(English Letters) 2012年第4期25卷 279-286页

作者： Limin SHEN jianming gong Yong JIANG Luyang GENG College of Mechanical and Power Engineering Nanjing University of TechnologyNanjing 210009China

HP40Nb steel, used as a candidate material for ethylene cracking furnace tube, suffers creep and carburization damage from the complex environment of high temperature, high carbon potential and low oxygen partial pressure, and they lead to failure of the furnace tubes ahead of designed life. In order to investigate damage evolution under the complex condition, coupled creep damage and carburization damage constitutive equations were developed according to continuum damage mechanics theory. Based on the finite element ABAQUS code, user subroutines were developed for analyz- ing damage evolution of ethylene furnace tube under the action of coupled creep- carburization. The results show that carburization accelerates the damage process dramatically, damage value reaches the critical value along the inner surface after serving for 75,000 h under the action of creep-carburization, meanwhile the damage value is only 0.53 along the outer surface after operating the same time under the action of creep alone, which means that microcracks are generated along the inner surface under the action of coupled creep-carburization, fracture begins along the outer surface of tube under the action of creep alone.

关键词： Damage prediction HP40Nb Coupled creep-carburizationEthylene furnace tube

Corrosion performance of Al–Al2O3 cold sprayed coatings on mild carbon steel pipe under thermal insulation

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Chinese Journal of Chemical Engineering 2017年第4期25卷 533-539页

作者： Xiaomin Bai Jianqun Tang jianming gong Xiaoliang Lü School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211816China

This paper focused on the corrosion resistance of cold spray Al–Al_2O_3composite coatings used on carbon steel pipe surfaces under thermal insulation. Al–Al_2O_3coatings were produced on the carbon steel pipe surface by cold spray(CS) technology. Experimental apparatus was built to test the corrosion resistance of coatings beneath mineral wool insulation under isothermal, thermal cycling and wet/dry conditions. The results showed that when α-Al_2O_3 was added in spraying powder, the coating could obtain higher hardness and a denser microstructure. From corrosionunder-insulation(CUI) tests, Al–Al_2O_3CS coatings were proven to be efficient in protecting carbon steel pipe from CUI mainly owning to lamellar microstructures of coatings. There was no evidence to show that α-Al_2O_3 might bring any negative effect on corrosion resistance. Al–Al_2O_3CS coatings were sensitive to the chloride ion concentration. When these coatings were exposed to higher concentrations of NaC l, the coating's exhibited faster degradation.

关键词： insulation spray lamellar cycling pipe hardness faster isothermal owning exposed

Gas Sources of Natural Gas Hydrates in the Muli Permafrost of Qilian Mountain

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Acta Geologica Sinica(English Edition) 2016年第6期90卷 2281-2282页

作者： CHENG Qingsong gong jianming ZHANG Min College of Resources and Environment Yangtze UniversityWuhan 430100HubeiChina Qingdao Institute of Marine Geology Qingdao 266071ShandongChina

The gas hydrates in the permafrost region of Qilian Mountain are characterized by low latitude, thin thickness, shallow burial depth, abundant coal seams, high contents of heavy hydrocarbons and multiple sets of sourc... 详细信息

关键词： Gas Sources of Natural Gas Hydrates in the Muli Permafrost of Qilian Mountain rock

Experimental and simulated characterization of creep behavior of P92 steel with prior cyclic loading damage

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Journal of Materials Science & Technology 2017年第12期33卷 1540-1548页

作者： Wei Zhang Xiaowei Wang jianming gong Yong Jiang Xin Huang School of Mechanical and Power Engineering Nanjing Tech UniversityNanjing 211816China Jiangsu Key Lab of Design and Manufacture of Extreme Pressure Equipment Nanjing 211816China Department of Material Textiles and Chemical EngineeringFaculty of Engineering and ArchitectureGhent University.Zwijnaarde B-9052Belgium

The effect of prior cyclic loading on creep behavior of P92 steel was investigated. Creep tests on prior cyclic loading exposure specimens were performed at 650？C and 130 MPa. In order to clarify the influence of prior cyclic loading on creep behavior, optical microscope, scanning electron microscope and transmission electron microscope were used. Experimental results indicate that the prior cyclic loading degrades the creep strength significantly. However, the degradation tends to be saturated with further increase in prior cyclic loading. From the view of microstructural evolution, the recovery of martensite laths takes place during prior cyclic loading exposure. This facilitates the dislocation movement during the following creep process. Therefore, premature rupture of creep test occurs. Additionally, saturated behavior of degradation can be attributed to the near completed recovery of martensite laths. Based on the effect of prior cyclic loading, a newly modified Hayhurst creep damage model was proposed to consider the prior cyclic loading damage. The main advantage of the proposed model lies in its ability to directly predict creep behavior with different levels of prior cyclic loading damage. Comparison of the predicted and experimental results shows that the proposed model can give a reasonable prediction for creep behavior of P92 steel with different level of prior cyclic loading damage.

关键词： Prior cyclic loading Creep behavior Martensite morphology Life prediction

Simulation experiments on gas production from hydrate-bearing sediments

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Science China Earth Sciences 2009年第1期52卷 22-28页

作者： gong jianming CAO ZhiMin CHEN JianWen ZHANG Min LI Jin YANG GuiFang College of Marine Geosciences Ocean University of ChinaQingdao 266003China Qingdao Institute of Marine Geology Qingdao 266071China Geochemical Department Yangtze UniversityJingzhou 434023China Langfang Branch Research Institute of Petroleum Exploration&DevelopmentPetroChinaLangfang 065007China

Experiments were made on 58 sediment samples from four sites (1244, 1245, 1250 and 1251) of ODP204 at five temperature points (25, 35, 45, 55 and 65°C) to simulate methane production from hydrate-bearing sediments. Simulation results from site 1244 show that the gas components consist mainly of methane and carbon dioxide, and heavy hydrocarbons more than C2 + cannot be detected. This site also gives results, similar to those from the other three, that the methane production is controlled by experimental temperatures, generally reaching the maximum gas yields per gram sediment or TOC under lower temperatures (25 and 35°C). In other words, the methane amount could be related to the buried depth of sediments, given the close relation between the depth and temperature. Sediments less than 1200 m below seafloor are inferred to still act as a biogenic gas producer to pour methane into the present hydrate zone, while sedimentary layers more than 1200 m below seafloor have become too biogenically exhausted to offer any biogas, but instead they produce thermogenic gas to give additional supply to the hydrate formation in the study area.

关键词： gas production simulation experiment hydrate-bearing sediments ODP204

Research on extracting method of micro-scale remote sensing information combination and application in coastal zone

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Acta Oceanologica Sinica 2009年第5期28卷 30-38页

作者： YANG Xiaomei ZHOU Chenghu gong jianming GAO Zhenyu Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

Due to the need of rapid and sustainable development in China’s coastal zones, the high-resolution information theory using data mining technology becomes an urgent research focus. However, the traditional pixel-based image analysis methods cannot meet the needs of this development trend. The paper attempts to present an information extraction approach in terms of image segmentation based on an object-oriented algorithm for high-resolution remote sensing images. An aim of the author’ research is to establish an identification system of ＂pixel-primitive-object＂. Through extraction and combination of micro-scale coastal zone features, some objects are classified or recognized, e.g., tidal flat, water line, sea wall, and mariculture pond. Firstly, the authors extract various internal features of relatively homogeneous primitive objects using an image segmentation algorithm based on both spectral and shape information. Secondly, the features of those primitives are analyzed to ascertain an optimal object by adopting certain feature rules. The results from this research indicate that our model is practical to realize and the extraction accuracy of the coastal information is significantly improved as compared with the traditional approaches. Therefore, this study provides a potential way to serve the author’ highly dynamic coastal zones for monitoring, management, development and utilization.

关键词： Object-oriented Image Segmentation Coastal Zone Information Extraction

Simulation of the Accumulation Process of Biogenic Gas Hydrates in the Shenhu Area of Northern South China Sea

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Acta Geologica Sinica(English Edition) 2016年第6期90卷 2285-2286页

作者： LIAO Jing gong jianming Lü Wanjun WU Nengyou YUE Baojing LUAN Xiwu HU Gaowei Qingdao Institute of Marine Geology Qingdao 266071ShandongChina China University of Geoscience Wuhan 430074HubeiChina

Previous work has largely discussed the relations between sediment structures and accumulation of gas hydrates in the Shenhu area of South China Sea, but has not documented why the gas hydrates occurred at the seafloor topographic highs. Many gas hydrate exploration examples abroad also indicate that the saturation of gas hydrates was higher at seafloor topographic highs. This work aims to understand why gas hydrates accumulated at topographic highs and why their saturation is higher.

关键词： area Simulation of the Accumulation Process of Biogenic Gas Hydrates in the Shenhu Area of Northern South China Sea than

The Gas-Source Study of Gas Hydrates in Wuli and Muli Permafrost Region of Qinghai-Tibet Plateau

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Acta Geologica Sinica(English Edition) 2015年第A01期89卷 443-445页

作者： gong jianming ZHANG Li ZHANG Min Key Laboratory of Marine Hydrocarbon Resources andEnvironmental Geology MLR Qingdao Shandong 266071 Qingdao Institute of Marine Geology Qingdao Shandong 266071 Guangzhou Marine Geological Survey MLR Guangzhou Guangdong 510760 School of Earth Environment and Water Resources Yangtze University Wuhan Hubei 430100

1 Introduction Muli permafrost region is located in the south Qilian Mountain of the northem Qinghai-Tibet Plateau, which belongs to Kunlun Mountain terrain in geo-tectonics （Fig.l）. The average elevation of the region is 4100m and the thickness of the permafrost is about 60 to 100m （ZHOU Youwu, etc, 2000; PAN Yulu, etc, 2008）.

关键词： GAS hydrates NATURAL gas HYDROCARBONS PLATE tectonics STABLE isotopes CARBON isotopes

Ductility loss of hydrogen-charged and releasing 304L steel

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Frontiers of Mechanical Engineering 2013年第3期8卷 298-304页

作者： Yanfei WANG jianming gong Yong JIANG Wenchun JIANG Wang JIANG College of Mechanical and Power Engineering Nanjing University of Technology College of Chemistry and Chemical Engineering China University of Petroleum Qingdao

The mechanical properties and fracture behavior of 304L austenitic stainless steel after cathodic hydrogen charging and hydrogen spontaneously releasing are investigated by tensile *** tensile specimens were cathodic hydrogen charged at various current *** each density,two specimens were charged at the same *** the charging process completed,one specimen was tensile immediately to fracture and the other was aged to release the hydrogen out of it and then was also tensile to *** resulting tensile properties and micrographs of fracture surfaces of these specimens were evaluated and *** results show ductility loss occurred in the hydrogen-charged specimens and the loss increased as the current density *** hydrogen releasing,the specimens recovered a certain extent but not all of its original *** electron microscope(SEM)micrographs of fracture surfaces reveal that irreversible damage had developed in the hydrogen-releasing specimens during the releasing process rather than the charging *** consequence can be ascribed to the high tensile stress caused by non-uniform hydrogen distribution during hydrogen releasing.

关键词： hydrogen embrittlement ductility loss hydrogen releasing control strategy 304L austenitic stainless steel