Blocking rockfalls directly by reinforced concrete(RC) flat sheds with thick sand cushions is an outdated method. Such conventional sheds typically accumulate rock heavily, and become progressively damaged and are dif...Blocking rockfalls directly by reinforced concrete(RC) flat sheds with thick sand cushions is an outdated method. Such conventional sheds typically accumulate rock heavily, and become progressively damaged and are difficult to repair, and are very costly. To address these problems, we propose a new structure called a Graded Dissipating Inclined Steel Rock(GDISR) shed that utilizes the graded energy dissipation method. Here, we study the dynamic response of the GDISR shed with model test and numerical simulation, and give its optimization design combining with a practical engineering case. Our results show that the optimized modular E-block and corrugated steel tube can deform to sufficiently absorb the energy of different impact intensities. This efficiently and economically provides GDISR sheds with two security lines. Compared with conventional RC sheds, GDISR sheds with optimal incline have a more efficient anti-impact function, are faster and easier to repair, and are much simpler and cheaper to build.展开更多
This paper presents isothermal uniaxial compression test results of M300 grade maraging steel over a wide range of temperatures(900 e1200℃) and strain rates(0.001 e100 s^(-1)) to examine hot deformability and concurr...This paper presents isothermal uniaxial compression test results of M300 grade maraging steel over a wide range of temperatures(900 e1200℃) and strain rates(0.001 e100 s^(-1)) to examine hot deformability and concurrent microstructural evolution. Processing map is generated and indicated the optimum processing parameters in the temperature range of 1125℃-1200℃ and strain rate range of 0.001 e0.1 s^(-1). High values of the efficiency of power dissipation, microstructural observations and EBSD results indicate softening mechanism to be the occurrence of dynamic recrystallisation. Material constants in a constitutive relation are evaluated from the flow stress data useful in computer modelling.展开更多
Aluminum/steel electric transition joints (ETJs) are used in aluminum reduction cell for the purpose of welding aluminum rod and steel bracket components. Solid state welding process used for joining aluminum and stee...Aluminum/steel electric transition joints (ETJs) are used in aluminum reduction cell for the purpose of welding aluminum rod and steel bracket components. Solid state welding process used for joining aluminum and steel at the electric transition joints have the drawbacks of cracking and separation at the interface surfaces. Cracking and separation at the electric transition joints are caused by the stress singularities that developed due to the mismatch in thermal and mechanical properties of each material. To overcome the drawback of electric transition joints, aluminum/steel functionally graded may be used as electric transition joints or proposed. Therefore manufacturing and investigation of aluminum/steel functionally graded materials fabricated by powder metallurgy process were carried out through the current work. Different samples with different layers of aluminum/steel functionally graded materials were compacted using steel die and punch at the same compacted pressure and sintered temperature. After investigating the different samples of aluminum/steel functionally graded materials under different fabrication conditions, the suitable fabrication regime was determined with the aid of microscopic observations.展开更多
目的:筛选c-MYC/Bcl-2重排的弥漫大B细胞淋巴瘤(diffuse large B-cell lymphoma,DLBCL)潜在的高风险致病基因及致病通路,为此类淋巴瘤的发病机制提供理论依据。方法:从基因表达数据库(GEO)下载GSE44164及GSE43677数据集,选择c-MYC/Bcl-...目的:筛选c-MYC/Bcl-2重排的弥漫大B细胞淋巴瘤(diffuse large B-cell lymphoma,DLBCL)潜在的高风险致病基因及致病通路,为此类淋巴瘤的发病机制提供理论依据。方法:从基因表达数据库(GEO)下载GSE44164及GSE43677数据集,选择c-MYC/Bcl-2重排的DLBCL数据为实验组、生发中心B细胞为对照组。采用R程序语言的limma包、WGCNA包及clusterProfiler包对获得的mRNA转录组数据进行差异表达分析、基因共表达变化分析、GO功能富集分析与KEGG信号通路富集分析。使用STRING数据库对差异表达基因(DEGs)进行蛋白互相作用网络分析,并使用Cytoscape软件内置的插件(包括CytoHubba及CytoNca插件)筛选核心基因。采用第二代高通量测序技术对IM-9细胞系及DOHH-2细胞系进行mRNA转录组测序,使用Read count值将核心基因进行配对样本t检验,筛选P值具有统计学意义的基因为疾病的核心基因。挑选部分关键基因使用Western Blot技术在蛋白层面进行验证。结果:差异分析共得到835个DEGs,WGCNA获得一个与c-MYC/Bcl-2重排的DLBCL高度相关的模块(turquoise模块,cor=0.86,P值<0.05)。GO富集分析结果显示生物学进程BP共富集到1 437条,细胞组分CC富集到123条,分子功能相关MF富集到147条;KEGG富集到72条相关通路,主要与ECM受体相互作用、B细胞受体信号通路及PI3K-Akt信号通路等相关。STRING数据库中PPI网络共得到284个相互关联作用的蛋白质,通过Cytoscape软件进一步筛选,再通过二代高通量测序及蛋白验证得出COL1A1、COL3A1、COL1A2、MMP2、COL5A1、COL5A2、COL4A2、TIMP1、MMP9、POSTN、BGN、DCN、LUM为此类淋巴瘤的核心基因,影响此类淋巴瘤细胞生存、侵袭和迁移等。结论:使用生物信息学及基础实验相结合的方法探究与c-MYC/Bcl-2重排的DLBCL淋巴瘤细胞致病或侵袭迁移等相关的关键基因,为更深入地探索此类淋巴瘤发生发展机制及寻找相关靶向药物提供理论依据。展开更多
In this study,the microstructure and mechanical properties of a multi-layered 316L-TiC composite material produced by selective laser melting(SLM)additive manufacturing process are investigated.Three different layers,...In this study,the microstructure and mechanical properties of a multi-layered 316L-TiC composite material produced by selective laser melting(SLM)additive manufacturing process are investigated.Three different layers,consisting of 316L stainless steel,316L-5 wt%TiC and 316L-10 wt%TiC,were additively manufactured.The microstructure of these layers was characterized by optical microscopy(OM)and scanning electron microscopy(SEM).X-ray diffraction(XRD)was used for phase analysis,and the mechanical properties were evaluated by tensile and nanoindentation tests.The microstructural observations show epitaxial grain growth within the composite layers,with the elongated grains growing predominantly in the build direction.XRD analysis confirms the successful incorporation of the TiC particles into the 316L matrix,with no unwanted phases present.Nanoindentation results indicate a significant increase in the hardness and modulus of elasticity of the composite layers compared to pure 316L stainless steel,suggesting improved mechanical properties.Tensile tests show remarkable strength values for the 316L-TiC composite samples,which can be attributed to the embedded TiC particles.These results highlight the potential of SLM in the production of multi-layer metal-ceramic composites for applications that require high strength and ductility of metallic components in addition to the exceptional hardness of the ceramic particles.展开更多
In this paper, an experimental and analytical study of two half-scale steel X-braced flames with equal nominal shear strength under cyclic loading is described. In these tests, all members except the braces are simila...In this paper, an experimental and analytical study of two half-scale steel X-braced flames with equal nominal shear strength under cyclic loading is described. In these tests, all members except the braces are similar. The braces are made of various steel grades to monitor the effects of seismic excitation. Internal stiffeners are employed to limit the local buckling and increase the fracture life of the steel bracing. A heavy central core is introduced at the intersection of the braces to decrease their effective length. Recent seismic specifications are considered in the design of the X-braced frame members to verify their efficiency. The failure modes of the X-braced frames are also illustrated. It is observed that the energy dissipation capacity, ultimate load capacity and ductility of the system increase considerably by using lower grade steel and proposed detailing. Analytical modeling of the specimens using nonlinear finite element software supports the experimental findings.展开更多
The bogie made of Grade B＋ steel is one of the most important parts of heavy haul trains. Some accidents were found to be the result of fracture failure of the bogies. It is very important to find the reason why the ...The bogie made of Grade B＋ steel is one of the most important parts of heavy haul trains. Some accidents were found to be the result of fracture failure of the bogies. It is very important to find the reason why the fracture failure occurred. Because AI was added for the final deoxidation during the smelting process of the Grade B＋Steel, residual AI existed to some extent in the castings. High residual AI content in the bogie casting was presumed to be the reason for the fracture. In this work, the influence of residual AI content in the range of 0.015wt.% to 0.3wt.% on the microstructure and mechanical properties of the Grade B＋ Steel was studied. The experimental results showed that when the residual AI content is between 0.02wt.% and 0.20wt.%, the mechanical properties of the steel meet the requirements of technical specification for heavy haul train parts, and the fracture is typical plastic fractures. If the residual AI content is less than 0.02wt.%, the microstructures are coarse, and the mechanical properties can not meet the demand of bogie steel castings. When the residual AI content is more than 0.2wt.%, the elongation, reduction of area, and low-temperature impact energy markedly deteriorate. The fracture mode then changes from plastic fracture to cleavage brittle fracture. Therefore, the amount of AI addition for the final deoxidation during the smelting process must be strictly controlled. The optimum addition amount needs to be controlled within the range of 0.02wt.% to 0.20wt.% for the Grade B＋Steel.展开更多
The development, production and application of top high-grade non-grain-oriented （NGO） silicon steels at Baosteel were introduced in this paper. Top high grades refer to the highest grades in the intemational silico...The development, production and application of top high-grade non-grain-oriented （NGO） silicon steels at Baosteel were introduced in this paper. Top high grades refer to the highest grades in the intemational silicon steel product standard and above. B35A230 and B50A250 were developed at Baosteel in 2009 and have been used in inverter compressors for air-conditioners, small transformers and big hydropower generators in the Three Gorges project. Small- batch production of B35A210 and B50A230, which exceed the highest grades listed in the intemational silicon steel product standard,began in 2010. That was a breakthrough in the silicon steel making history in China. Presently,Baosteel＇ s high- grade NGO products have passed the strict qualifications of the three major electric power equipment manufacturers in China and the leading international power equipment suppliers like ALSTOM, GE, SIEMENS, VESTAS, etc. These products are characterized by low iron loss, low anisotropy, good punchability and a high lamination factor. They have been used in the 770 MW hydropower generator at Xiluodu Power Station in the three gorges area, 1 000 MW thermal power generators and 2.5 MW wind power generators.展开更多
To reduce distribution transformer losses and carbon dioxide emissions, in recent years, the major countries in the world have issued mandatory standards for high-energy efficiency in distribution transformers. In 201...To reduce distribution transformer losses and carbon dioxide emissions, in recent years, the major countries in the world have issued mandatory standards for high-energy efficiency in distribution transformers. In 2013,China has carried out a new standard GB 20052-2013. To meet the update of the standard and energy efficiency,it is important to enhance the magnetic properties of core materials. The new products B18R065 and B20R070 which are developed by Baosteel, are successfully used for grade 1 energy efficiency distribution transformers. And Baosteel becomes one of the companies which can supply both the 0.20 mm and the 0.18 mm gauge grain oriented electrical steels （GOES） in the world. The development principle, material properties, and transformer performance of B18R065 and B20R070 were introduced,which were expected to be a useful reference for materials selection by transformer manufacturers.展开更多
采用转炉→精炼炉→真空脱气→方坯连铸→加热→粗轧→中轧→精轧→减定径→吐丝→XDWP(Xingcheng Direct Water Patenting)冷却→斯太尔摩风冷冷却的方式试验生产基于10B21钢的8.8级非调紧固件用热轧盘条。通过控制减定径温度为813℃,...采用转炉→精炼炉→真空脱气→方坯连铸→加热→粗轧→中轧→精轧→减定径→吐丝→XDWP(Xingcheng Direct Water Patenting)冷却→斯太尔摩风冷冷却的方式试验生产基于10B21钢的8.8级非调紧固件用热轧盘条。通过控制减定径温度为813℃,吐丝温度为828℃,斯太尔摩辊道速率设置为0.75 m/s,在连续经过XDWP冷却和斯太尔摩风冷后获得的热轧盘条抗拉强度达到680 MPa,断后伸长率为23.6%,断面收缩率为75%,力学性能完全满足GB/T 29087―2012的要求。且经过1/4冷顶锻和25%的大减面率拉拔试验,其结果满足紧固件用户使用要求。展开更多
A preparation technology of MgO powder used in special silicon steel from hydromagnesite mineral has been developed. The preparation technology includes the following steps： （1） calcining the hydromagnesite at 700-...A preparation technology of MgO powder used in special silicon steel from hydromagnesite mineral has been developed. The preparation technology includes the following steps： （1） calcining the hydromagnesite at 700-750°C for 1.5-2 h; （2） hydrating the calcined hydromagnesite to be slurry containing the solid-liquid ratio of 15-20 g？L？1; （3） acquiring Mg（HCO3）2 solution by carbonating the slurry, the carbonation temperature, CO2 pressure, and end point PH value of carbonation are less than 40°C, 0.4-0.6 MPa, and 7 respectively during the carbonation process; （4） preparing precipitated basic magnesium carbonate by thermally decomposing the Mg（HCO3）2 solution at 90-100°C; （5） obtaining the MgO product by calcining the precipitated basic magnesium carbonate at 850-950°C for 30-60 min, and adopting flowing nitrogen during the cooling process. By using this technology, more than 80wt% magnesium in hydromagnesite mineral can be extracted, and high-performance MgO products used in special silicon steel can be ob- tained.展开更多
基金supported by the National Key Basic Research Program of China(2016YFB0201003)the National Natural Science Foundation of China(41672356)the 135 Strategic Program of the Institute of Mountain Hazards and Environment,CAS(SDS-135-1704)
文摘Blocking rockfalls directly by reinforced concrete(RC) flat sheds with thick sand cushions is an outdated method. Such conventional sheds typically accumulate rock heavily, and become progressively damaged and are difficult to repair, and are very costly. To address these problems, we propose a new structure called a Graded Dissipating Inclined Steel Rock(GDISR) shed that utilizes the graded energy dissipation method. Here, we study the dynamic response of the GDISR shed with model test and numerical simulation, and give its optimization design combining with a practical engineering case. Our results show that the optimized modular E-block and corrugated steel tube can deform to sufficiently absorb the energy of different impact intensities. This efficiently and economically provides GDISR sheds with two security lines. Compared with conventional RC sheds, GDISR sheds with optimal incline have a more efficient anti-impact function, are faster and easier to repair, and are much simpler and cheaper to build.
文摘This paper presents isothermal uniaxial compression test results of M300 grade maraging steel over a wide range of temperatures(900 e1200℃) and strain rates(0.001 e100 s^(-1)) to examine hot deformability and concurrent microstructural evolution. Processing map is generated and indicated the optimum processing parameters in the temperature range of 1125℃-1200℃ and strain rate range of 0.001 e0.1 s^(-1). High values of the efficiency of power dissipation, microstructural observations and EBSD results indicate softening mechanism to be the occurrence of dynamic recrystallisation. Material constants in a constitutive relation are evaluated from the flow stress data useful in computer modelling.
文摘Aluminum/steel electric transition joints (ETJs) are used in aluminum reduction cell for the purpose of welding aluminum rod and steel bracket components. Solid state welding process used for joining aluminum and steel at the electric transition joints have the drawbacks of cracking and separation at the interface surfaces. Cracking and separation at the electric transition joints are caused by the stress singularities that developed due to the mismatch in thermal and mechanical properties of each material. To overcome the drawback of electric transition joints, aluminum/steel functionally graded may be used as electric transition joints or proposed. Therefore manufacturing and investigation of aluminum/steel functionally graded materials fabricated by powder metallurgy process were carried out through the current work. Different samples with different layers of aluminum/steel functionally graded materials were compacted using steel die and punch at the same compacted pressure and sintered temperature. After investigating the different samples of aluminum/steel functionally graded materials under different fabrication conditions, the suitable fabrication regime was determined with the aid of microscopic observations.
文摘In this study,the microstructure and mechanical properties of a multi-layered 316L-TiC composite material produced by selective laser melting(SLM)additive manufacturing process are investigated.Three different layers,consisting of 316L stainless steel,316L-5 wt%TiC and 316L-10 wt%TiC,were additively manufactured.The microstructure of these layers was characterized by optical microscopy(OM)and scanning electron microscopy(SEM).X-ray diffraction(XRD)was used for phase analysis,and the mechanical properties were evaluated by tensile and nanoindentation tests.The microstructural observations show epitaxial grain growth within the composite layers,with the elongated grains growing predominantly in the build direction.XRD analysis confirms the successful incorporation of the TiC particles into the 316L matrix,with no unwanted phases present.Nanoindentation results indicate a significant increase in the hardness and modulus of elasticity of the composite layers compared to pure 316L stainless steel,suggesting improved mechanical properties.Tensile tests show remarkable strength values for the 316L-TiC composite samples,which can be attributed to the embedded TiC particles.These results highlight the potential of SLM in the production of multi-layer metal-ceramic composites for applications that require high strength and ductility of metallic components in addition to the exceptional hardness of the ceramic particles.
文摘In this paper, an experimental and analytical study of two half-scale steel X-braced flames with equal nominal shear strength under cyclic loading is described. In these tests, all members except the braces are similar. The braces are made of various steel grades to monitor the effects of seismic excitation. Internal stiffeners are employed to limit the local buckling and increase the fracture life of the steel bracing. A heavy central core is introduced at the intersection of the braces to decrease their effective length. Recent seismic specifications are considered in the design of the X-braced frame members to verify their efficiency. The failure modes of the X-braced frames are also illustrated. It is observed that the energy dissipation capacity, ultimate load capacity and ductility of the system increase considerably by using lower grade steel and proposed detailing. Analytical modeling of the specimens using nonlinear finite element software supports the experimental findings.
基金financially supported by the Heilongjiang Province Natural Science Foundation(QC2010110)
文摘The bogie made of Grade B＋ steel is one of the most important parts of heavy haul trains. Some accidents were found to be the result of fracture failure of the bogies. It is very important to find the reason why the fracture failure occurred. Because AI was added for the final deoxidation during the smelting process of the Grade B＋Steel, residual AI existed to some extent in the castings. High residual AI content in the bogie casting was presumed to be the reason for the fracture. In this work, the influence of residual AI content in the range of 0.015wt.% to 0.3wt.% on the microstructure and mechanical properties of the Grade B＋ Steel was studied. The experimental results showed that when the residual AI content is between 0.02wt.% and 0.20wt.%, the mechanical properties of the steel meet the requirements of technical specification for heavy haul train parts, and the fracture is typical plastic fractures. If the residual AI content is less than 0.02wt.%, the microstructures are coarse, and the mechanical properties can not meet the demand of bogie steel castings. When the residual AI content is more than 0.2wt.%, the elongation, reduction of area, and low-temperature impact energy markedly deteriorate. The fracture mode then changes from plastic fracture to cleavage brittle fracture. Therefore, the amount of AI addition for the final deoxidation during the smelting process must be strictly controlled. The optimum addition amount needs to be controlled within the range of 0.02wt.% to 0.20wt.% for the Grade B＋Steel.
文摘The development, production and application of top high-grade non-grain-oriented （NGO） silicon steels at Baosteel were introduced in this paper. Top high grades refer to the highest grades in the intemational silicon steel product standard and above. B35A230 and B50A250 were developed at Baosteel in 2009 and have been used in inverter compressors for air-conditioners, small transformers and big hydropower generators in the Three Gorges project. Small- batch production of B35A210 and B50A230, which exceed the highest grades listed in the intemational silicon steel product standard,began in 2010. That was a breakthrough in the silicon steel making history in China. Presently,Baosteel＇ s high- grade NGO products have passed the strict qualifications of the three major electric power equipment manufacturers in China and the leading international power equipment suppliers like ALSTOM, GE, SIEMENS, VESTAS, etc. These products are characterized by low iron loss, low anisotropy, good punchability and a high lamination factor. They have been used in the 770 MW hydropower generator at Xiluodu Power Station in the three gorges area, 1 000 MW thermal power generators and 2.5 MW wind power generators.
文摘To reduce distribution transformer losses and carbon dioxide emissions, in recent years, the major countries in the world have issued mandatory standards for high-energy efficiency in distribution transformers. In 2013,China has carried out a new standard GB 20052-2013. To meet the update of the standard and energy efficiency,it is important to enhance the magnetic properties of core materials. The new products B18R065 and B20R070 which are developed by Baosteel, are successfully used for grade 1 energy efficiency distribution transformers. And Baosteel becomes one of the companies which can supply both the 0.20 mm and the 0.18 mm gauge grain oriented electrical steels （GOES） in the world. The development principle, material properties, and transformer performance of B18R065 and B20R070 were introduced,which were expected to be a useful reference for materials selection by transformer manufacturers.
文摘采用转炉→精炼炉→真空脱气→方坯连铸→加热→粗轧→中轧→精轧→减定径→吐丝→XDWP(Xingcheng Direct Water Patenting)冷却→斯太尔摩风冷冷却的方式试验生产基于10B21钢的8.8级非调紧固件用热轧盘条。通过控制减定径温度为813℃,吐丝温度为828℃,斯太尔摩辊道速率设置为0.75 m/s,在连续经过XDWP冷却和斯太尔摩风冷后获得的热轧盘条抗拉强度达到680 MPa,断后伸长率为23.6%,断面收缩率为75%,力学性能完全满足GB/T 29087―2012的要求。且经过1/4冷顶锻和25%的大减面率拉拔试验,其结果满足紧固件用户使用要求。
基金the Science and Technology Program Project of Hunan Province, China (No.06SK2011).
文摘A preparation technology of MgO powder used in special silicon steel from hydromagnesite mineral has been developed. The preparation technology includes the following steps： （1） calcining the hydromagnesite at 700-750°C for 1.5-2 h; （2） hydrating the calcined hydromagnesite to be slurry containing the solid-liquid ratio of 15-20 g？L？1; （3） acquiring Mg（HCO3）2 solution by carbonating the slurry, the carbonation temperature, CO2 pressure, and end point PH value of carbonation are less than 40°C, 0.4-0.6 MPa, and 7 respectively during the carbonation process; （4） preparing precipitated basic magnesium carbonate by thermally decomposing the Mg（HCO3）2 solution at 90-100°C; （5） obtaining the MgO product by calcining the precipitated basic magnesium carbonate at 850-950°C for 30-60 min, and adopting flowing nitrogen during the cooling process. By using this technology, more than 80wt% magnesium in hydromagnesite mineral can be extracted, and high-performance MgO products used in special silicon steel can be ob- tained.
