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Fractional Cooling Strategy of the Hot-Stamping Process and Its Influence on Formability and Mechanical Properties of Ultra-High-Strength Steel Parts

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Acta Metallurgica Sinica(English Letters) 2019年第3期32卷 343-351页

作者： xian-hong Han Cheng-Long Wang Si-Si Chen Jun Chen Department of Plasticity Technology School of Materials Science and Engineering Shanghai Jiao Tong University SAIC General Motors Co. Ltd

The effects of forming temperature on the formability and product properties of hot-stamping boron steel B1500HS were investigated. Based on the fractional cooling strategy, boron steel sheets were heated to achieve full austenitization before they were removed from the furnace and cooled to the forming temperature using different cooling methods. Subsequently,they were simultaneously press-formed and quenched inside the tool until the martensitic transformation was finished. A series of thermal tensile tests were conducted to study the effects of forming temperatures on the stamping performance indices, including elongation, yield ratio, and hardening exponent. Then, the mechanical properties and microstructures of the hot-stamped products were characterized. Finally, an irregular part was formed using different fractional cooling strategies, while its formability and springback phenomena were discussed. The results show that using a fast-cooling method to reach 650 °C as the forming temperature optimizes the formability of the tested B1500HS boron steel. The best mechanical properties and smallest springback values were achieved using this optimal strategy.

关键词： Hot-stamping Fractional cooling Forming temperature Formability

Effect of H impurity on misfit dislocation in Ni-based single-crystal superalloy:molecular dynamic simulations

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Chinese Physics B 2012年第2期21卷 407-412页

作者： Yu Tao Xie hong-xian Wang Chong-Yu Central Iron and Steel Research Institute Beijing 100081China Department of Physics Tsinghua UniversityBeijing 100084China School of Mechanical Engineering Hebei University of TechnologyTianjin 300132China

The effect of H impurity on the misfit dislocation in Ni-based single-crystal superalloy is investigated using the molecular dynamic simulation. It includes the site preferences of H impurity in single crystals Ni and Ni3Al, the interaction between H impurity and the misfit dislocation and the effect of H impurity on the moving misfit dislocation. The calculated energies and simulation results show that the misfit dislocation attracts H impurity which is located at the γ/γ′ interface and Ni3Al and H impurity on the glide plane can obstruct the glide of misfit dislocation, which is beneficial to improving the mechanical properties of Ni based superalloys.

关键词： molecular dynamic H impurity misfit dislocation Ni-based superalloy

RO-heparin Inhibits L-Selectin-mediated Neutrophils Adhesion to Vascular Endothelium Under Flow Conditions

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Chemical Research in Chinese Universities 2006年第3期22卷 302-307页

作者： CHEN Zhi-hong XU Li BA Xue-qing ZENG xian-lu Institute of Genetics and Cytology Northeast Normal University Changchun 130024 P. R. China School of Life Science Mudanjiang Medical University Mudanjiang 157011 P. R. China Biology Section College of Changchun Traditional Chinese Medicine Changchun 130017 P. R. China

Selectins are carbohydrate-binding cell adhesion molecules that play a major role in the initiation of inflammatory responses. Accumulaed evidence has suggested that heparin＇s anti-inflammatory effects are mainly mediated by blocking L-or P-selectin-initiated cell adhesion. Recently, we have reported that periodate-oxidized, borohydridereduced heparin （RO-heparln） can inhibit P-selectin-mediated acute inflammation. Here we further examined the effect of RO-heparin on the adhesion of L-selectin-mediated leukocytes to vascular endothelium under flow conditions in vivo and in vitro. The results show that RO-heparin with a low anticoagulant activity can effectively reduce leucocyte roiling on thioglycoUate-induced rat mesenterlc venules and L-selectin-metadiated neutrophil roiling on TNF-α-induced human umbilical vein endothelial cells（HUVECs） under flow conditions. Our findings suggest that the effect of RO-heparin on inflammatory responses is mainly a result of its inhibiting the interaction between P- or L-selectin and its ligands. The findings also suggest that RO-heparin may be useful in preventing inflammation diseases.

关键词： RO-heparin Neutrophils adhesion L-selectin Human umbilical vein endothelial cells (HUVECs)

Fracture morphologies of a hot stamped steel and comparisons with several sheet metals

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Journal of Iron and Steel Research International 2017年第6期24卷 634-640页

作者： Shu-lin Tan Kun Yang Ya-nan Ding xian-hong Han Department of Plasticity Technology Shanghai Jiao Tong University Shanghai 200030 China Institute of Chemical Material China Academy of Engineering Physics Mianyang 621900 Sichuan China Department of Civil and Environmental Engineering Northwestern University Evanston 60208 Illinois USA

Hot stamping has been widely used in car industry to produce safety components. Most existing re- searches focused on the stamping and quenching process, but less on the mechanical properties of stamped parts. The fracture behaviors of hot stamped boron steel B1500HS have been studied, and other four commonly used sheet metals with different strengths, including Q235, TRIP780, QP980 and MS1300, were also introduced for comparison. Both uniaxial tests and mechanical trimming tests were performed, and the fracture surfaces under different stress states were observed and discussed. The SEM observations showed that the fracture models are closely related to the stress states, i. e., the tensile surfaces have ductile rupture characters while the trimming surfaces have brittle rupture characters. Compared with other steels, the quenched boron steel has smaller dimple size accompa- nied by shear planes in the tensile surface, and has smaller burnish zone in the trimming surface, and its cutting surface with ＇S＇ like shape is also very different with others. Furthermore, two fitted em pirical models were derived to describe the quantitative correlations between the average dimple diam- eter and the steel strength and between the percentage of burnish zone and the steel strength.

关键词： Hot stamped steelFracture morphologyTensile testMechanical trimming testSteel comparison

Childbirth expectations and correlates at the final stage of pregnancy in Chinese expectant parents

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International Journal of Nursing Sciences 2014年第2期1卷 151-156页

作者： xian Zhang hong Lu Nursing College Zhengzhou UniversityZhengzhouChina School of Nursing Peking UniversityBeijingChina

Purpose:To explore the childbirth expectations of Chinese expectant parents during their transition to ***:A cross-sectional descriptive survey was used through the Chinese version of the Childbirth Expectations Questionnaire.A total of 240 expectant parents were recruited when they were admitted to the obstetric units waiting for delivery at a large Maternal and Child Health care Center in Beijing,and 210 couples completed the questionnaires,yielding a response rate of 87.5%.Results:The expectant parents had a high level of childbirth expectations towards caregiving environment,spousal support,control and participation and medical ***,their expectations toward labor pain and their own ability to cope with the pain were relatively *** fathers’childbirth expectations and preference of partner’s accompany were two significant predictors of expectant mothers’childbirth expectations,explaining 18.9%and 3.3%of the total variance,*** expectant mothers’childbirth expectations was the only significant predictor of expectant fathers’childbirth ***:This study adds to understanding of the childbirth expectations of Chinese expectant *** is suggested that maternity healthcare providers pay close attention to the childbirth expectations of expectant parents,and improve the nursing care service to promote positive childbirth experiences and satisfaction of expectant parents.

关键词： Childbirth expectation Chinese Expectant parents Maternity care

Understanding micro-diffusion bonding from the fabrication of B_4C/Ni composites

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International Journal of Minerals,Metallurgy and Materials 2018年第3期25卷 365-374页

作者： Miao Wang Wen-xian Wang hong-sheng Chen Yu-li Li College of Materials Science and Engineering Taiyuan University of Technology Key Laboratory of Interface Science and Engineering in Advanced Materials Ministry of Education Taiyuan University of Technology

A Ni-B_4C macroscopic diffusion welding couple and a Ni-15 wt% B_4C composite fabricated by spark plasma sintering(SPS) were used to understand the micro-scale diffusion bonding between metals and ceramics. In the Ni-B_4C macroscopic diffusion welding couple a perfect diffusion welding joint was achieved. In the Ni-15 wt% B_4C sample, microstructure analyses demonstrated that loose structures occurred around the B_4C particles. Energy dispersive X-ray spectroscopy analyses revealed that during the SPS process, the process of diffusion bonding between Ni and B_4C particles can be divided into three stages. By employing a nano-indentation test, the room-temperature fracture toughness of the Ni matrix was found to be higher than that of the interface. The micro-diffusion bonding between Ni and B_4C particles is quite different from the Ni-B_4C reaction couple.

关键词： B4C/Ni composites spark plasma sintering micro-diffusion welding microstructure nano-mechanical property

Intensive construction technology for urban underground parking shaft

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FRONTIERS OF STRUCTURAL AND CIVIL ENGINEERING 2024年第11期18卷 1649-1662页

作者： Jiang, hong Liu, xian Bao, Heli Bi, Jinfeng Lin, Tao He, Tengfei Shanghai Urban Construct Design & Res Inst Shanghai 200125 Peoples R China Tongji Univ Coll Civil Engn Shanghai 200092 Peoples R China

As urban construction continues to develop and automobile ownership rises, parking shortages in cities have become increasingly acute. Given the limited availability of land resources, conventional underground garages and parking buildings no longer suffice to meet the growing demand for parking spaces. To address this dilemma, underground parking shaft (UPS) has emerged as a highly regarded solution. This study provides an overview of the layout scheme, structural design approaches, and construction techniques for UPS, focusing on the characteristics of intensive construction demonstrated in the project located in the Jianye District of Nanjing. Compared to conventional vertical shaft garage construction methods, this assembly parking shaft offers advantages such as a smaller footprint, higher prefabrication rate, shorter construction period, and reduced environmental impact. It presents an efficient approach for the intensive construction of urban underground spaces, particularly in areas with limited land and complex environments, showing promising prospects for widespread application.

关键词： intensive construction parking shaft assembly underground garage

Liquid-phase epoxidation of propylene with molecular oxygen by chloride manganese meso-tetraphenylporphyrins

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Chinese Journal of Chemical Engineering 2022年第8期35卷 61-65页

作者： xian-Tai Zhou Ling-Ling Wang Yang Li hong-Bing Ji Fine Chemical Industry Research Institute School of Chemical Engineering and TechnologySun Yat-sen UniversityZhuhai 519082China Fine Chemical Industry Research Institute School of ChemistrySun Yat-sen UniversityGuangzhou 510275China School of Chemical Engineering Guangdong University of Petrochemical TechnologyMaoming 525000China

Propylene molecule owns two active sites,the direct epoxidation of propylene by dioxygen is still a challenge due to the limitation of *** this work,the direct liquid-phase propylene aerobic epoxidation protocol by chloride manganese meso-tetraphenylporphyrin(MnTPPCl)was *** conversion of propylene was 12.7%,and the selectivity towards PO(propylene oxide)reached up to 80.5%.The formation of PO was attributed to the mechanism via high-valent Mn species,which was confirmed by means of in situ UV–vis spectrum.

关键词： Propylene Epoxidation Dioxygen Manganese porphyrins Liquid phase

Promotion and Mechanism of Acupotomy on Chondrocyte Autophagy in Knee Osteoarthritis Rabbits

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Chinese Journal of Integrative Medicine 2024年第9期30卷 809-817页

作者： LU Man meng De-hong SHE Ze-yu WU xian XIA Shuai YANG Kai-ning LIU Cun-bin LI Tao YANG Yong-hui The First Affiliated Hospital of Anhui University of Chinese Medicine Hefei230031China The Second Affiliated Hospital of Anhui University of Chinese Medicine Hefei230038China Department of Acupotomy Rehabilitation Anhui Provincial Hospital of Integrated Traditional Chinese and Western MedicineHefei230031China

Objective:To explore the effect of acupotomy intervention on autophagy of chondrocytes in rabbits with knee osteoarthritis(KOA),and to determine the possible mechanisms of acupotomy to alleviate cartilage ***:The modified Videman method was used to construct a KOA rabbit *** modeling,40 rabbits were randomly divided into 4 groups by a random number table:control;KOA(model);KOA+acupotomy(acupotomy),and KOA+sham acupotomy(sham),10 in each *** a 3-week treatment course,the knee joint activity was determined by the modified Lequesne MG ***-eosin staining staining was used to examine the morphological changes of *** of chondrocytes was observed by transmission electron *** surface morphology of cartilage tissue was observed by scanning electron *** mRNA and protein levels of AMP kinase/mammalian target of rapamycin/Unc-51(AMPK/mTOR/ULK1)signal pathway key proteins,autophagy-related factor Beclin-1 and microtubule-associated protein 1A/1B light chain 3(LC3)in rabbit knee cartilage were assessed by real-time fluorescence quantitative polymerase chain reaction and Western blot,***:The modified Lequesne MG score of acupotomy group was significantly lower than that of model group(P<0.05).Pathological results showed that chondrocyte autophagy decreased and cartilage surface was rough in the model group,which recovered after acupotomy *** mRNA expressions of AMPK,ULK1,Beclin-1 and the protein levels of p-AMPK,p-ULK1,Beclin-1,and LC3Ⅱ/LC3Ⅰwere decreased in the model group,while the mRNA and protein expressions of mTOR were increased(P<0.01).However,acupotomy treatment reversed these abnormal changes(P<0.05).Conclusions:Acupotomy could effectively up-regulate the expressions of AMPK,ULK1 and Beclin1,reduce the expression of mTOR,promote autophagy,and alleviate joint *** is a promising complementary and alternative therapy for KOA.

关键词： acupotomy knee asteoarthritis autophagy AMPK/mTOR/ULK1 signaling pathway rabbit