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Hot Stamping Parameters Optimization of Boron Steel Using a Response Surface Methodology Based on Central Composite Design

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Journal of Iron and Steel Research International 2015年第6期22卷 519-526页

作者： Ming-dong HUANG bao-yu wang Jing ZHOU School of Mechanical Engineering University of Science and Technology Beijing

The effect of hot stamping parameters on the mechanical properties of 22MnB5 steel sheet with thickness of 1.1 mm is studied. The considered parameters are austenization temperature （800- 1 000 ℃ ）, austenitizing soa king time （60-540 s）, initial deformation temperature （560-800 C） and tool temperature （20-220 ℃）. In order to obtain hot stamped parts with optimal mechanical properties, response surface methodology based on the central composite design has been employed to design the experiment matrix. Tensile strength of hot stamped parts is deter- mined as the relation in the mathematical model. The optimal condition and objective effects of parameters are deter mined via this relation. The statistical analysis showed that all four factors significantly affect the tensile strength of the hot stamped parts. The optimum austenization temperature is found to be 918.89 ℃ with the austenitizing soa- king time, initial deformation temperature and tool temperature of 279.45 s, 684.69 C and 21.85 ℃, respectively. These optimal hot stamping parameters prove to have high tensile strength （1 631.84 MPa） where deviation between predicted and actual response falls within 2 %.

关键词： hot stamping advanced high strength steel response surface method optimization

Spin injection in a ferromagnet/resonant tunneling diode heterostructure

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Journal of University of Science and Technology Beijing 2008年第5期15卷 638-643页

作者： Jin bao Fang Wan yu wang Xiaoguang Xu Yong Jiang School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

The spin transport property of a ferromagnet （FM）/insulator （Ⅰ）/resonant tunneling diode （RTD） heterostructure was studied. The transmission coefficient and spin polarization in a multilayered heterostructure was calculated by a Schrdinger wave equation. An Airy function formalism approach was used to solve this equation. Based on the transfer matrix approach,the transmittivity of the structure was determined as a function of the Feimi energy and other parameters. The result shows that the spin polarization induced by the structure oscillates with the increasing Fermi energy of the FM layer. While the thickness of the RTD is reduced,the resonant peaks become broad. In the heterostructure,the spin polarization reaches as high as 40% and can be easily controlled by the external bias voltage.

关键词： spin injection resonant tunneling diode heterostructure spin polarization

Effect of hot stamping parameters on the mechanical properties and microstructure of cold-rolled 22MnB5 steel strips

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International Journal of Minerals,Metallurgy and Materials 2014年第6期21卷 544-555页

作者： Jing Zhou bao-yu wang Ming-dong Huang Dong Cui School of Mechanical Engineering University of Science and Technology Beijing

Thermomechanical experiments were carried out to reproduce the hot stamping process and to investigate the effects of process parameters on the microstructure and mechanical properties of stamped parts. The process parameters, such as austenitizing temperature, soaking time, initial deformation temperature and cooling rate, are studied. The resulting microstructures of specimens were observed and analyzed. To evaluate the mechanical properties of specimens, tensile and hardness tests were also performed at room temperature. The op-timum parameters to achieve the highest tensile strength and the desired microstructure were acquired by comparing and analyzing the results. It is indicated that hot deformation changes the transformation characteristics of 22MnB5 steel. Austenite deformation promotes the austen-ite-to-ferrite transformation and elevates the critical cooling rate to induce a fully martensitic transformation.

关键词： boron steel strip metal stamping mechanical properties microstructure phase transitions

Ductile fracture behavior of TA15 titanium alloy at elevated temperatures

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International Journal of Minerals,Metallurgy and Materials 2015年第10期22卷 1082-1091页

作者： Lei Yang bao-yu wang Jian-guo Lin Hui-jun Zhao Wen-yu Ma School of Mechanical Engineering University of Science and Technology Beijing Department of Mechanical Engineering Imperial College LondonLondon SW7 2AZUK

To better understand the fracture behavior of TA15 titanium alloy during hot forming, three groups of experiments were conducted to investigate the influence of deformation temperature, strain rate, initial microstructure, and stress triaxiality on the fracture behavior of TA15 titanium alloy. The microstructure and fracture surface of the alloy were observed by scanning electronic microscopy to analyze the potential fracture mechanisms under the experimental deformation conditions. The experimental results indicate that the fracture strain increases with increasing deformation temperature, decreasing strain rate, and decreasing stress triaxiality. Fracture is mainly caused by the nucleation, growth, and coalescence of microvoids because of the breakdown of compatibility requirements at the α/β interface. In the equiaxed microstructure, the fracture strain decreases with decreasing volume fraction of the primary α-phase(αp) and increasing α/β-interface length. In the bimodal microstructure, the fracture strain is mainly affected by α-lamella width.

关键词： titanium alloys ductile fracture elevated temperat

Modeling of microstructural evolution and flow behavior of superalloy IN718 using physically based internal state variables

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Rare Metals 2022年第8期41卷 2759-2766页

作者： Xue-Feng Tang bao-yu wang Ning Zhang yuan-Ming Huo Jing Zhou School of Mechanical Engineering University of Science and Technology BeijingBeijing100083China Beijing Aeronautical Manufacturing Technology Research Institute Beijing100024China

Microstructural evolution and flow behavior greatly affect the hot forming process of *** this research,hot deformation behaviors of IN718 were investigated by performing hot compression tests at temperature range of 1000-1100℃with strain rates of 0.1-20.0 s^(-1).By incorporating physically based internal state variables such as dislocation density,volume fraction of dynamic recrystallization,and grain size,a set of unified viscoplastic constitutive equations were developed to predict the microstructural evolution and flow behavior of *** material constants were determined using a genetic algorithm(G A)-based optimization *** of the computed and experimental results indicate that the constitutive equations established in this study can accurately describe the hot deformation behavior and microstructural evolution of IN718.

关键词： IN718 Microstructural evolution Flow behavior Constitutive equations Internal state variables

Deep drawing of aluminum alloy 7075 using hot stamping

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Rare Metals 2017年第6期36卷 485-493页

作者： Wen-Chao Xiao bao-yu wang Yi Kang Wei-Ping Ma Xue-Feng Tang School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China

In this paper, simulations of deep drawing tests at elevated temperatures were carried out with experimental validation. The aim of this work was to study the effect of process parameters on formability and mechanical properties of aluminum alloy 7075 in hot stamping *** parameters, including blank temperature, stamping speed, blank holder force and friction coefficient, were studied. Stamping tests were conducted at temperatures between 350 and 500 ℃, blank holder force between 0 and 10 kN, stamping speed between 50 and 150 mm·s^-1, and friction coefficient between 0.1 and 0.3. Based on the analysis, it is shown that thickness homogeneity could be improved when the blank is formed at lower temperature,lower blank holder force and lower friction *** could be improved when the blank was well lubricated at about 400 ℃. Formability at stamping speed 50 mm·s^-1 is far better than those at other speeds. The mechanical property analysis shows that the hot stamping process could make the formed part to obtain high quality.

关键词： Aluminum alloy 7075 Aluminum hotstamping Process parameters Formability Mechanicalproperty

Molecular structure characterization of middle-high rank coal via^(13)C NMR,XPS,and FTIR spectroscopy

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China Geology 2024年第4期7卷 702-713页

作者： Xiao-ming Ni Jing-shuo Zhang Xiao-kai Xu bao-yu wang School of Energy Science and Engineering Henan Polytechnic UniversityJiaozuo 454000China Institute of Resources&Environment Henan Polytechnic UniversityJiaozuo 454000China

Elemental analysis,nuclear magnetic resonance carbon spectroscopy(^(13)C-NMR),X-ray photoelectron spectroscopy(XPS)and Fourier transform infrared spectroscopy(FTIR)experiments were carried out to determine the existence of aromatic structure,heteroatom structure and fat structure in ***(materials studio)software was used to optimize and construct a 3D molecular structure model of coal.A method for establishing a coal molecular structure model was formed,which was“determination of key structures in coal,construction of planar molecular structure model,and optimization of three-dimensional molecular structure model”.The structural differences were compared and *** results show that with the increase of coal rank,the dehydrogenation of cycloalkanes in coal is continuously enhanced,and the content of heteroatoms in the aromatic ring *** heteroatoms and branch chains in the coal are reduced,and the structure is more orderly and *** stability of the structure is determined by theπ-πinteraction between the aromatic rings in the nonbonding energy *** Stretching Energy The size of EB determines how tight the structure *** research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.

关键词： Molecular structure model Carbon-13 nuclear magnetic resonance(NMR) X-ray photoelectron spectroscopy(XPS) Fourier transform infrared spectroscopy(FTIR) Coal

Influence of process parameters on properties of AA6082 in hot forming process

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Transactions of Nonferrous Metals Society of China 2017年第11期27卷 2454-2463页

作者： Wen-yu MA bao-yu wang Jian-guo LIN Xue-feng TANG School of Mechanical Engineering University of Science and Technology Beijing Beijing 100083 China Department of Mechanical Engineering Imperial College London London SW7 2AZ UK

The influences of process parameters on mechanical properties of AA6082in the hot forming and cold-die quenching(HFQ)process were analysed *** electron microscopy was used to observe the precipitate distribution and to thus clarify strengthening mechanism.A new model was established to describe the strengthening of AA6082by HFQ process in this novel forming *** material constants in the model were determined using a genetic algorithm *** strengthening model for AA6082can precisely describe the relationship between the strengths of formed workpieces and process *** predicted results agree well with the experimental *** Pearson correlation coefficient,average absolute relative error,and root-mean-square error between the calculated and experimental hardness values are0.99402,2.0054%,and2.045,*** model is further developed into an FE code ABAQUS via VUMAT to predict the mechanical property variation of a hot-stamped cup in various ageing conditions.

关键词： aluminium alloy AA6082 mechanical properties strengthening model hot forming

Detection of markers of hepatitis viral infection in the tissue of bile duct carcinoma

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Chinese Medical Journal 2008年第12期121卷 1143-1144页

作者： LIU Hou-bao QIAN Zhen-yu wang Bing-sheng TONG Sai-xiong Department of General Surgery Zhongshan Hospital Fudan University Shanghai 200032 China

Hepatitis 15 virus （HBV） IS an admitted oncogenic virus. Many epidemiological and molecularbiological studies have demonstrated that chronic infection with HBV is a major risk factor associated with the development of hepatocellular carcinoma （HCC） and intrahepatic bile duct cancer. Compared with hepatocytes and intrahepatic bile duct epithelial cells, extrahepatic bile duct epithelial cells have autoploid in embryogenesis, continuity in anatomy and a similar internal environment. The question arises whether extrahepatic bile duct epithelial cells can receive HBV infection or not？ The role of hepatitis viral infection in the pathogenesis of bile duct carcinoma has not yet been clarified, although a causative relationship between HBV or HCV infection and extrahepatic bile duct carcinoma has been reported in the literature. In this study, we focused on the evidence of hepatitis viral infection in tissue of bile duct carcinoma.

关键词： hepatitis viral infection bile duct carcinoma biomarker