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Influence of dynamic recrystallization on microstructure and mechanical properties of welding zone in Al-Mg-Si aluminum profile during porthole die extrusion

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Transactions of Nonferrous Metals Society of China 2019年第9期29卷 1803-1815页

作者： Shi-kang LI Luo-xing LI Hong HE Zhi-wen LIU Long ZHANG State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China

The effect of dynamic recrystallization(DRX)on the microstructure and mechanical properties of 6063 aluminum alloy profile during porthole die extrusion was studied through experiment and *** grain morphology was observed by means of electron backscatter diffraction(EBSD)*** results show that,at low ram speeds,increasing the ram speed caused an increase in DRX fraction due to the increase of temperature and strain *** contrast,at high ram speeds,further increasing ram speed had much less effect on the temperature,and the DRX faction decreased due to high stain *** microhardness and fraction of low angle boundaries in the welding zones were lower than those in the matrix *** grain size in the welding zone was smaller than that in the matrix zone due to lower DRX *** decrease of grain size and increase of extrudate temperature were beneficial to the improvement of microhardness.

关键词： 6063 aluminum alloy porthole die extrusion dynamic recrystallization microstructure mechanical properties

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.

Isothermal extrusion speed curve design for porthole die of hollow aluminium profile based on PID algorithm and finite element simulations

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Transactions of Nonferrous Metals Society of China 2021年第7期31卷 1939-1950页

作者： Jie YI Zhi-wen LIU Wen-qi ZENG School of Mechanical Engineering Hunan Industry PolytechnicChangsha 410208China School of Mechanical Engineering University of South ChinaHengyang 421001China

The isothermal extrusion process of hollow aluminium profile was investigated using incremental proportional-integral-derivative(PID)control algorithm and finite element *** range of extrusion speed was determined by considering the maximum extrusion load and production *** taking the optimal solution temperature of the secondary phase as the target temperature,the extrusion speed–stroke curve for realizing the isothermal extrusion of the aluminium profile was *** show that in the traditional constant extrusion speed process,the average temperature of the cross-section of the aluminium profile at the die exit rapidly increases and then slowly rises with the increase in ram *** the extrusion speed increases,the temperature difference at the die exit of the profile along the extrusion direction *** exit temperature difference between the front and back ends of the extrudate along the extrusion direction obtained by adopting isothermal extrusion is about 6.9℃.Furthermore,the heat generated by plastic deformation and friction during extrusion is balanced with the heat transfer from the workpiece to the container,porthole die and external environment.

关键词： isothermal control extrusion speed curve porthole die extrusion PID control heat balance

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

Formability evaluation of AZ31B extruded tube for hydroforming process

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Rare Metals 2007年第S1期26卷 83-87页

作者： HE Zhubin,LIU Gang,YUAN Shijian,and LIANG Yingchun School of Materials Science & Engineering,Harbin Institute of Technology,Harbin 150001,China Harbin Inst Technol Sch Mat Sci & Engn Harbin 150001 Peoples R China

Hydroforming of magnesium and aluminum alloy tube at elevated temperature is becoming a very promising method to manufacture light-weight hollow *** tensile test and hydrobulging test were used to investigate the formability of AZ31B magnesium tube at different *** tube was manufactured by porthole die *** show that as temperature increase,the tension formability along the extrusion direction measured by tensile test increases significantly,whereas the maximum hydrobulging ratio measured by hydrobulging test does not change *** anisotropy character of the tube,i.e.,different properties in axial direction and hoop direction,is mainly dependant on the extrusion *** addition,there exists several weld lines along the extrusion *** weld lines will become the weakest positions when formed at elevated temperature,and will consequently decrease the formability of the tube during hydroforming process.

关键词： AZ31B magnesium alloy extruded tube hydrobulging test porthole die extrusion