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On a plastic instability criterion for ultra-large radial-axial ring rolling process with four guide rolls

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Chinese Journal of Aeronautics 2022年第6期35卷 391-406页

作者： Xuechao LI Lianggang GUO Fengqi WANG Research&Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057China State Key Laboratory of Solidification processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China

A dynamic mechanical model is proposed to describe the complexing actions of all the rolls on the ring during the ultra-large radial-axial ring rolling(RARR)process with four guide *** on the model,the calculation models for bending moment and normal stress at any section of the ring are deduced by force *** the maximum section bending normal stress exceeds the yield stress of the ring materials,the ring will be distorted thus leading to the instability of the RARR *** to this,a plastic instability criterion for the ultra-large RARR process with four guide rolls is developed,based on which a mathematical model to calculate the critical guide force for avoiding plastic instability of ring is *** influence rule of the position of guide roll on the dangerous ring section of plastic instability is revealed,from which it is found the dangerous ring section mainly appears at the radial and axial deformation regions and the contact positions of the guide rolls and *** optimized layout of guide roll around the ring in favor of stability is determined to be about a1=61°and a2=119°.The plastic instability criterion is proven to be reliable from the aspects of the critical guide force,the section bending moment and normal stress and the dangerous ring section of plastic *** simulation case studies for the RARR process of ultra-large aluminum alloy ring indicate that the stable forming of the process can be effectively realized by regulating the guide force based on the plastic instability *** work could provide a valuable guidance for the control of guide rolls and the optimization of the ultra-large RARR process with four guide rolls.

关键词： Four guide rolls Guide force Plastic instability criterion Radial-axial ring rolling Ultra-large ring

Investigation on the 773 K isothermal section of La-Fe-Sn ternary systems by X-ray powder diffraction

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Rare Metals 2010年第6期29卷 567-571页

作者： CHEN Xiang ZHUANG Yinghong CHEN Yungui Key Laboratory of Nonferrous Metal and New processing Technology of materials (Ministry of Education of China) Guangxi University Nanning 530004 China Department of Physics and Electronic Information Engineering Neijiang Teachers College Neijiang 641002 China Department of Metallic materials Engineering Sichuan University Chengdu 610065 China

The 773 K isothermal section of the La-Fe-Sn ternary system was investigated and constructed by X-ray powder diffraction（XRD）.The existence of two reported ternary intermetallic compounds,La6Fe13Sn and La3FeSn6,is confirmed in this *** with other R-Fe-Sn phase diagrams（R = Pr and Sm）,the binary alloys Fe3Sn and Fe5Sn3 are not *** compound Fe3Sn2 was observed from the XRD pattern of Fe3Sn2 samples,but it is not an equilibrium phase at 773 K and decomposes into Fe and FeSn phases completely for a longer heat treated *** to now,the crystal structure data of La2Sn3 has not been reported,so the X-ray pattern of La2Sn3 was only *** phase relationship for this compound was drawn by a dotted line.

关键词： intermetallics quenching phase diagrams X-ray diffraction.

Microtextural evolution of different TRC AA8006 alloy sections with homogenization

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International Journal of Minerals,Metallurgy and materials 2015年第3期22卷 292-301页

作者： Zhong-wei Chen Long-fei Shen Jing Zhao State Key Laboratory of Solidification processing Northwestern Polytechnical University

Grain microtexture evolution in twin-roll cast AA8006 alloy sheets subjected to different treatments was investigated using elec- tron backscatter diffraction. The textures of rolling-transverse and normal-transverse sections were characterized in original as-cast twin-roll casting and cold-rolled samples as well as samples homogenized at 500℃for 8 h and at 580℃ for 4 h. It is found that grains on both the rolling-transverse and normal-transverse sections of cold-rolled samples are made fmer by rolling deformation and coarsened after homog- enization. Annealing temperature has a stronger effect on the microstructural evolution than annealing time. The grain growth direction is parallel to the normal-transverse section, while grain deformation is more stable on the rolling direction than on the normal direction. The rolling orientations display more obvious anisotropy on the normal-transverse sections than on the rolling-transverse sections. Grain recrys- tallization and growth occur much easier on the normal-transverse section than on the rolling-transverse section for samples homogenized at 500℃ for 8 h. A special misorientation relationship between cold deformation texture, such as S orientation { 123 } 〈634〉 and cube orienta- tion 〈110〉Xaxis [cubic], and recrystallization texture after homogenization, such as R orientation { 124}〈211〉 and P orientation {011 }〈122〉, is observed.

关键词： aluminum alloys textures twin-roll casting homogenization

Exploiting Loop Parallelism with Redundant Execution

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Journal of Computer Science & Technology 1997年第2期12卷 105-112页

作者：唐卫宇施武臧斌宇朱传琪 Institute of Parallel processing Fudan University Shanghai

In this paper, a new loop transformation is proposed that can exploit parallelism in loops which cannot be found by traditional methods. Then the method is extended to show how to achieve maximum speedup of loops if there are infinite processors and how to balance the workload of parallel sections in loops i f there is fixed number of processors.

关键词： Parallel compiler loop transformation parallel section maximum speedup

Determination of continuous constitutive relationship of weld zone of high-strength steel rectangular welded tube

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Journal of Iron and Steel Research International 2020年第10期27卷 1212-1225页

作者： Hai-long Liu Yu-li Liu Zhong Yang Kun Wang Meng-meng Liu Research and Development Institute of Northwestern Polytechnical University in Shenzhen Shenzhen 518057Guangdong.China State Key Laboratory of Solidification processing School of Materials Science and EngineeringNorthwestern Polytechnicai UniversityXi'an 710072ShaanxiChina

For QSTE700 high-strength steel rectangular welded tube,the mechanical properties of the weld zone vary with the distancefrom the centerline of the ***,the accurate description of constitutive relationship of the weld zone is of greatsignificance for the study of formability of QSTE700 rectangular welded ***,the mechanical properties of parentand mixed specimens containing weld zone and parent zone were obtained by uniaxial tensile *** based on the micro-hardness test,the width and the microhardness distribution of the weld zone were ***,by subdividingthe weld zone into several small areas,and combining with the rule of mixtures and nanoindentation test,the continuous functional relationships of strength coefficient K,hardening coeffecient n and elastic modulus E were obtained,and then,the continuous constitutive relationship of QSTE700 rectangular welded tube was ***,the validity and reliability of the continuous constitutive relationship of welded tube were verified by nanoindentation fest and rotary drawbending of rectangular welded ***,it was found that the finite element model of rotary draw bending of QSTE700 rectangular welded tube established by using the continuous constitutive relationship can well simulate the cross sectiondeformation and wall thickness variation.

关键词： QSTE700 high-strength steel rectangular welded tube Continuous constitutive relationship-Nanoindentation test Rotary draw bending process Cross section deformation Wall thickness variation

Formation mechanism and evolution of surface coarse grains on a ZK60 Mg profile extruded by a porthole die

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Journal of materials Science & Technology 2020年第12期47卷 88-102页

作者： Jianwei Tang Liang Chen Guoqun Zhao Cunsheng Zhang Xingrong Chu Key Laboratory for Liquid-Solid Structural Evolution and processing of materials(Ministry of Education) Shandong University.Jinan 250061China Associated Engineering Research Center of Mechanics and Mechatronic Equipment Shandong UniversityWeihai 264209China

Porthole die extrusion of Mg alloys was studied by means of experimental and numerical studies. Results indicated that an inhomogeneous microstructure formed on the cross-section of the extruded profile. On the profile surface, abnormal coarse grains with an orientation of in parallel to ED(extrusion direction) appeared. In the profile center, the welding zone was composed of fine grains with an average size of 4.19 um and an orientation of in parallel to ED, while the matrix zone exhibited a bimodal grain structure. Disk-like, near-spherical and rod-like precipitates were observed, and the number density of those features was lower on the profile surface than that in the profile center. Then, the formation and evolution of coarse grains on the profile surface were investigated, which were found to depend on the competition between static recrystallization and grain growth. The stored deformation energy was the factor dominating the surface structure through effective regulation over nucleation of the precipitates and recrystallization. A profile with a low stored deformation energy suppressed formation of precipitates and consequently facilitated grain growth rather than recrystallization, resulting in the formation of abnormal coarse grains. Finally, the surface coarse grains contributed detrimentally to hardness, tensile properties, and wear performance of the bulk structure.

关键词： Porthole die extrusion Abnormal coarse grains Stored deformation energy Recrystallization

Investigation of the Ion-Exchange Behavior of Zeolite Y in the Presence of Resin

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China Petroleum processing & Petrochemical Technology 2015年第2期17卷 50-56页

作者： Zhang Yi Zheng Jinyu Liu Zhongqing Gao Xiuzhi Luo Yibin Zong Baoning SINOPEC Research Institute of Petroleum processing

Ion-exchange process of zeolite Y using ammonium-type resin as an exchange reagent was successfully carried out. The effect of temperature, space velocity and ion concentration on the breakthrough curves was carefully investigated. At the first exchange section, the maximum proportion of qualified zeolites(QR) was obtained at a temperature of 70 ℃, a weight hourly space velocity of 0.61 h-1, and an ion concentration of 197 mg/L. The minimum length of mass-transfer zone(MTZ) of the resin bed was achieved at a temperature of 70 ℃, a space velocity of 0.61 h-1, and an ion concentration of 423 mg/L. At the second exchange section, the length of MTZ of the resin bed was significantly increased, and the exchange of Na+ ions contained in zeolite Y was more difficult than that achieved at the first exchange section. In both the first and the second exchange sections, the zeolite Y subjected to ion exchange with the resin maintained the similar physical and chemical properties as compared to those exchanged by the conventional approaches, but the zeolite Y, which was obtained after ion exchange, contained a significantly lower content of Na2 O.

关键词： zeolite Y resin ion-exchange

Effect of process parameters on the morphology of aluminum/copper alloy lap joints by red and blue hybrid laser welding

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China Welding 2024年第2期33卷 23-30页

作者：宋曜祥肖梦智黄德才张瑞华尹燕茹恩光吴怡霖 State Key Laboratory of Advanced processing and Recycling of Nonferrous Metals Lanzhou730050China China Iron&Steel Research Institute Group Beijing100081China Hardware Knife Cut Industrial Technology Research Institute Yangjiang Yangjiang529533China Guangdong Hall Laser Technology Co. Ltd.Foshan528251China

In order to overcome the problems of many pores,large deformation and unstable weld quality of traditional laser welded aluminumcopper alloy joints,a red-blue dual-beam laser source and a swinging laser were introduced for welding.T2 copper and 6063 aluminum thin plates were lap welded by coaxial dual-beam laser *** morphology of weld cross section was compared to explore the influence of process parameters on the formation of lap *** microstructure characteristics of the weld zone were observed and compared by optical *** results show that the addition of laser beam swing can eliminate the internal pores of the *** the increase of the swing width,the weld depth decreases,and the weld width increases first and then *** influence of welding speed on the weld cross section morphology is similar to that of swing *** the increase of welding speed,the weld width increases first and then decreases,while the weld depth decreases all the *** is because that the red laser is used as the main heat source to melt the base metals,with the increase of red laser power,the weld depth *** an auxiliary laser source,blue laser reduces the total energy consumption,consequently,the effective heat input increases and the spatter is restrained *** a result,the increase of red laser power has an enhancement effect on the weld width and weld *** the swing width is 1.2 mm,the red laser power is 550 W,the blue laser power is 500 W,and the welding speed is 35 mm/s,the weld forming is the *** lap joint of T2 copper and 6063 aluminum alloy thin plate can be connected stably with the hybrid of blue *** effect rules of laser beam swing on the weld formation were obtained,which improved the quality of the joints.

关键词： laser welding aluminum/copper alloy dual beam process parameters weld morphology

STUDIES ON ISOLATION AND PURIFICATION OF GLUCAGON

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Chinese Science Bulletin 1981年第2期26卷 191-192页

作者：尚克进凌启阆李建民李翠凤江南王风珍 section of Biochemistry Nankai University The Second Food processing Factory Tianjin The Second Food processing Factory

Glucagon is a polypeptide hormone of 29 amino acids which is synthesized by the α-cell of the islets of Langerhans of pancreas. One of its effects is to cause glycogenolysis and an increase in blood suger. In recent years it has been found that glucagon has several biological effects including the effect on contractility in cardiac muscle. Much attention has been drawn to this Subject. Since the strueture of glucagon is rather flexible, it is readily attcked by

关键词： glucagon Langerhans pancreas readily polypeptide drawn filtration Insulin isolation resin