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Buster Die Shape Design of a Track Link Forging Using FEM Based Back-Tracing Method

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Journal of Materials Science & Technology 2001年第1期17卷 139-140页

作者： guoqun zhao Xue DENG Mold&Die Engineer Technology Research Center Shandong University of TechnologyJinan 250061China

For the preform design of a complex track link forging, fifteen critical sections were selected for two dimensional back-tracing using FEM. The preform shapes of the critical sections are designed and integrated into an ideal 3D busting shape. The buster dies are finally designed according to the ideal busting shape with a little of modification. The 3D simulation of the busting stage is carried out.

关键词： two dimensional preform design

Sensitivity Analysis Based Multiple Objective Preform Die Shape Optimal Design in Metal Forging

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Journal of Materials Science & Technology 2006年第2期22卷 273-278页

作者： Xinhai zhao guoqun zhao Guangchun WANG Tonghai WANG Department of Materials Science ＆ Engineering Shandong University Jinan 250061 China

The multiple objective preform design optimization was put forward. The final forging＇s shape and deformation uniformity were considered in the multiple objective. The objective is to optimize the shape and the deformation uniformity of the final forging at the same time so that a more high integrate quality of the final forging can be obtained. The total objective was assembled by the shape and uniformity objective using the weight adding method. The preform die shape is presented by cubic B-spline curves. The control points of B-spline curves are used as the design variables. The forms of the total objective function, shape and uniformity sub-objective function are given. The sensitivities of the total objective function and the sub-objective functions with respect to the design variables are developed. Using this method, the preform die shape of an H-shaped forging process is optimally designed. The optimization results are very satisfactory.

关键词： Forging Preform Sensitivity Shape Deformation uniformity

Strategy for suppressing abnormal grain growth of ZK60 Mg alloy during solution by pre-compression:A quasi-in-situ study

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Journal of Materials Science & Technology 2024年第4期171卷 115-128页

作者： Zhenxu Wang Liang Chen Jianwei Tang Cunsheng Zhang guoqun zhao Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinanShandong 250061China Department of Mechanical Engineering Kyushu UniversityFukuoka 819-0395Japan

Abnormal grain growth(AGG)easily takes place in Mg alloys during high-temperature solutions,result-ing in deterioration of mechanical ***,the compression prior to solution(pre-compression)was conducted to suppress AGG,and the microstructure evolution as well as suppressing mechanisms was investigated based on quasi-in-situ *** compression along the transverse direction,//ED grains preferentially nucleated and rapidly grew up,and the initial//ED texture was *** grain growth modes of heat-induced and strain-induced grain boundary migrations were *** former was attributed to the high interfacial energy of grain boundaries with large *** latter consumed the adjacent grains with high storage energy,forming abnormal grains with irregular *** compression with a reduction>6%could obviously suppress *** suppressing effects were mainly attributed to weakening the size advantage of//ED grains,increasing nucleation,reducing grain boundary character distribution,and redistributing storage energy *** 12%compression along the transverse direction,30°misorientation of//ED grains and high energy grain boundaries were ***{10-12}tensile twins and{10-15}high index twins induced by com-pression increased the nucleation of static ***,compression introduces high-density dislocations,which also contributed to suppressing AGG behavior during solution.

关键词： Quasi-in-situ analysis Mg alloy Abnormal grain growth Compression Microstructure

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

Temperature change and stress distribution analysis of die surface in Al-alloy die casting process and experimental study on die heat check

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China Foundry 2008年第1期5卷 47-53页

作者： Hu Xinping zhao guoqun Wu Bingyao School of Material Science and Engineering Shandong University Jinan 250061 China School of Mechanical Engineering Shandong Institute of Light Industry Jinan 250353 China School of Material Science and Engineering Southeast University Nanjing 210096 China

The temperature change of the die surface in practical aluminum alloy die casting process was analyzed,and a 2D model was formulated on the basis of a deep concave round cavity without sliding core to analyze thestress distributions along the die surface in detail. Equipment was designed to test the thermal state of the die steelin different thermal loading conditions. The results of stress analysis showed that, the value of thermal stress (maximum1.5 GPa) caused in the die filling and die spraying stages was larger than the mechanical stress (maximum 85 MPa)caused in the die locking stage. The results of the thermal check experiment showed that there were three stages ofdie dissolving, and that the stress distribution shown by the samples' cracking routine was close to the die surfacestress analysis.

关键词： die temperature die stress die filling die locking die spraying die casting

Suppressing abnormal grain growth and switching precipitation behaviors in ZK60 Mg profile by inducing pre-tension

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Journal of Materials Science & Technology 2023年第24期155卷 89-101页

作者： Jianwei Tang Liang Chen Zhigang Li Biaohua Que guoqun zhao Cunsheng Zhang Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinan 250061China

The pre-tension was induced to suppress the abnormal grain growth(AGG)of ZK60 Mg profile during solution *** effects of pre-tension on the microstructure evolution and mechanical properties were studied,and the suppressing mechanism was *** the pre-tension strain was larger than 10%,AGG during solution could be effectively inhibited,resulting in a sharp decrease in the grain *** suppression effects were realized by restricting the orientation dependent of AGG and promoting static *** pre-tension reset the distributions of stored energy and sizes of the grains with〈11–20〉and〈10–10〉orientations,and thus retarded the orientation dependent of ***,the pre-tension introduced a mass of dislocations,twins,and stacking faults,all of which promoted the occurrence of static recrystallization,and the grain structure was further *** pre-tension accelerated the precipitation kinetics during aging,resulting in fine and dense *** the increase of pre-tension strain,the strength of ZK60 Mg profile monotonically increased.

关键词： Mg alloy Abnormal grain growth Pre-tension Microstructure Mechanical properties

Robust, breathable, and chemical-resistant polytetrafluoroethylene (PTFE) films achieved by novel in-situ fibrillation strategy for highperformance triboelectric nanogenerators

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Nano Research 2024年第3期17卷 1942-1951页

作者： Jialong Chai Guilong Wang Jinchuan zhao Guizhen Wang Chao Wei Aimin Zhang guoqun zhao Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinan 250061China Key Laboratory of Chinese Education Ministry for Tropical Biological Resources Hainan UniversityHaikou 570228China

In the era of advanced wearable electronic devices,the triboelectric nanogenerators(TENGs)as energy harvesting and self-powered sensing units hold great *** appropriate triboelectric material is the crucial factor to optimize the performance of TENG,while polytetrafluoroethylene(PTFE)stands out as a highly versatile option among the various *** this study,we present an ultrafine nanofibrous PTFE(NF-PTFE)films prepared by novel in-situ fibrillation strategy as the triboelectric material in TENG *** innovative processing methodology facilely addresses the dilemma between high porosity and fine pore size of traditional porous PTFE films,meanwhile achieves exceptional mechanical strength,hydrophobicity,air permeability,and chemical resistance of the *** the integration of nanofibrous PTFE films into contact-separation mode TENG and droplet-based TENG,these devices realize the peak electrical output of 131 V/10.8μA and 54 V/14μA with great durability,which surpass the performance of TENGs using traditional expanded PTFE ***,a smart glove capable of recognizing hand gestures is proposed,which demonstrates the versatility,flexibility,and practicality of this material for potential use in smart *** reported NF-PTFE film provides insights for the design of high-performance TENG device for advanced wearable electrical applications.

关键词： polytetrafluoroethylene(PTFE) nanofibrous film hydrophobic triboelectric nanogenerator self-powered sensor

Microstructure evolution of spray deposited and as-cast 2195 Al-Li alloys during homogenization

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Journal of Materials Science & Technology 2021年第23期82卷 161-178页

作者： Yongxiao Wang Xinwu Ma guoqun zhao Xiao Xu Xiaoxue Chen Cunsheng Zhang Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinan250061China

In this paper,a comparative study on the spray deposited and as-cast 2195 alloy was carried out to reveal their microstructure evolutions and differences during the homogenization *** dissolution of the secondary particles and the diffusion of solute were studied based on microstructure characterization and kinetics *** precipitation behavior of Al3Zr dispersoids and its influence on recrystallization were investigated by using TEM and EBSD *** was found that the large-size particles at triangular grain boundaries dissolve slower than the intragranular phases and other grain boundary *** required homogenization time depends on the dissolution processes of the large-size phases at grain *** size of grain boundary phases in the spray deposited alloy is much smaller than that in the as-cast alloy,so the homogenization time required for the spray deposited alloy is significantly ***-stage and ramp heating homogenization processes can promote the precipitation of Al3Zr dispersoids in the two *** the spray deposited alloy,the dispersoids tend to precipitate at the positions of the T1 plates dissolved,which causes a non-uniform distribution and decreases the recrystallization resistance of the ***,the distribution of the dispersoids in the as-cast alloy is more uniform after the homogenization,which brings a stronger inhibition on the *** to the microstructural characterization and kinetics analysis results,it can be concluded that the homogenization with a slow ramp heating is suitable for the two 2195 alloys,and a shorter holding time can be used for spray deposited alloy,e.g.12 h at 500℃,while the holding time for the as-cast alloy is no less than 35 h at 500℃.

关键词： Al-Li alloy Homogenization Dispersoids Recrystallization Diffusion kinetics

Achieving three-layered Al/Mg/Al sheet via combining porthole die co-extrusion and hot forging

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Journal of Magnesium and Alloys 2020年第3期8卷 654-666页

作者： Jianwei Tang Liang Chen guoqun zhao Cunsheng Zhang Lu Sun Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials(Ministry of Education) Shandong UniversityJinanShandong 250061PR China

Al/Mg/Al sheet with good bonding quality and mechanical properties was fabricated based on the proposed porthole die co-extrusion and forging(PCE-F)*** were no voids,cracks or other defects on the Al/Mg interface.A continuous diffusion zone with two-sub-layer structure was formed across the Al/Mg interface,and its width increased with higher temperature or reduction *** sub-layers formed at low and high temperature were identified to be solid solutions and intermetallic compounds(IMCs)including y-MgpAl^and^-*** Al layer,the welding zone mainly consisted of fine equiaxed grains with several coarse elongated grains,while the majority of matrix zone is coarse elongated *** rolling textures were dominated in both welding and matrix *** Mg layer,the welding zone exhibited complete DRXed grain structure,while several unDRXed coarse grains were observed in the matrix *** the increasing temperature,the grain size of Al and Mg layer firstly decreased and then *** reduction ratio strongly refined the grain structure of Al layer,while slightly affected the Mg *** Al/Mg/AI sheet experienced stress-drops twice during the tensile *** first stress-drop was determined by the IMCs and microstructure of Mg layer,while the second stress-drop was closely related to the microstructure of Al ***/Mg/Al sheet forged at the lowest temperature without the formation IMCs exhibited the highest stress for the first stress-drop,and that forged under the highest reduction ratio with the smallest grain size in Al layer had the highest stress for the second stress-drop.

关键词： Al/Mg/Al Porthole die extrusion Forging Microstructure Mechanical properties.