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Enhancing strength and ductility in back extruded WE71 magnesium alloy cylindrical parts by introduction of multi-direction forging process

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Journal of Rare Earths 2023年第3期41卷 462-470,I0006页

作者： Dehao Bu Ting Li Xiaolei Han Zhiwei Du Jiawei Yuan Kui Zhang Yongjun Li Yonggang Peng Zheng Pang Chunlei Zhao National Center of Analysis and Testing for Nonferrous Metals and Electronic Materials GRINM Group Co.Ltd.Beijing 100088China Guobiao(Beijing)Testing&Certification Co. Ltd.China United Test&Certification Co.Ltd.Beijing 100088China General Research Institute for Nonferrous Metals Beijing 100088China State Key Laboratory for Fabrication and Processing of Non-Ferrous Metals GRIMAT Engineering Institute Co.Ltd.Beijing 101407China Gaona Aero Material Co. Ltd.Beijing 100081China

Magnesium cylindrical parts have relatively poor mechanical properties and distinct anisotropy of microstructure,which hinder their application as structural *** improve the performance of WE71 cylindrical parts,multi-direction forging(MDF)was introduced before back extrusion,and the microstructure and mechanical properties were *** of microstructure show that the grain size in the outer of the cylindrical bottom is refined from 30.1 to 27.7μm,the micro structure is more uniform and the dislocation density is *** bimodal grain structure is formed in the outer of the cylindrical wall,which is ascribed to the formation of MgsRE phases along grain *** phases result in the Zener pinning effect on grain boundaries and the reduction of DRX volume *** texture type of the cylindrical bottom is‖ED and the cylindrical wall is‖ED,and the maximum pole intensity is 1.986 and 1.664,*** of the tensile test at room temperature show that combined improved strength and ductility of the cylindrical part is attained after introducing the MDF *** ultimate tensile strength(UTS),yield strength(YS)and elongation are279 MPa,185 MPa and 12%at the bottom and 299 MPa,212 MPa and 20%at the wall.

关键词： WE71 magnesium alloy Multi-direction forging backward extrusion Bimodal grain structure Rare earths

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Hot deformation in nanocrystalline Nd-Fe-B backward extruded rings

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Chinese Physics B 2011年第10期20卷 402-406页

作者：李安华赵睿赖彬王会杰朱明刚李卫 Division of Functional Materials Central Iron & Steel Research Institute

Radially oriented Nd-Fe-B rings are prepared by backward extrusion of fine grained melt-spun powder. Melt- spun powder with the nominal composition of ***6.0Ga0.6A10.2B0.9 （wt%） is used as starting material. The effects of process variables, such as deformation temperature （Td）, strain rate （ε） and height reduction （△h%）, on the magnetic properties of the rings are investigated. A scanning electron microscope （SEM） equipped with an energy spectrum device is used to study the metallograph and microfracture of the extruded rings. The Br and （BH）max reach the optimum values at Td =800℃,ε= 0.01 mm/s, and △h% = 70%. It is found by SEM observations that the particle boundaries, which seemingly correspond to the interfaces of the starting melt-spun powders, emerge after the corrosion of metallography specimens. This is helpful for studying the effects of powder-powder interface on the local deformation and deformation homogeneity in the rings. For different spatial positions of the extruded rings, there are characteristic metallographies and microfractures. The upper end of the rings has the least deformation and worst texture, and therefore the worst magnetic properties. The magnetic properties in the radial direction increase slightly along the axis from the bottom to the middle, then steeply decrease at the upper end of the ring. The deformation and the formation-of-texturing processes are discussed. The deformation and the texturing formation of melt-spun Nd-Fe-B alloys probably involve grain boundary sliding and grain rotation, the solution-precipitation process and preferential growth of Nd2Fel4B nanograins along the easy growth a-axis.

关键词： radially oriented Nd-Fe-B rings backward extrusion microstructure texture

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Structural and magnetic properties of backward extruded Nd–Fe–B ring magnets made by different punch chamfer radius

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Rare Metals 2014年第3期33卷 304-308页

作者： Ren-Quan Wang Biao Chen Jun Li Ying Liu Qing Zheng School of Materials Science and Engineering Sichuan University

Radially oriented Nd-Fe-B ring magnets were prepared by backward extrusion of MQ-C powder. The punch chamfer radius has a great impact on the microstructure and magnetic properties of the ring magnet. With the chamfer radius changing from 2, 5 to 8 mm, the cracks in the inner wall decrease obviously while the crystallographic alignment drops. Furthermore, the mechanism of caxis growth was suggested to be a combination of shear deformation in the corner and solution-precipitation under the stress parallel to radial direction. The alignment drops on the top of ring because the grains grow freely and some textured grains grow through nucleation and recrystallization. In the present work, the optimal punch chamfer radius is found to be 2 mm, and in this case, the remanence,coercivity, and maximum energy product of the ring magnet achieve 1.4 T, 670 kJám, and 342 kJám,respectively.

关键词： backward extrusion Nd-Fe-B ring magnet Microstructure Alignment

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Inhomogeneity of density and mechanical properties of A357 aluminum alloy backward extruded in semi-solid state

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Transactions of Nonferrous Metals Society of China 2011年第10期21卷 2285-2293页

作者：杜之明陈刚程远胜谢水生哈尔滨工业大学材料科学与工程学院哈尔滨150001 北京有色金属研究总院有色金属制造与加工国家重点实验室北京100088

The inhomogeneity of density and mechanical properties of A357 aluminum alloy in the semi-solid state were *** simulation and backward extrusion were adopted to study the preparation of cup *** results show that the relative density of the wall is the lowest in samples,and that of the base is the *** increasing the billet height,more time is needed for relative density of the corner to reach the maximum value,and the relative densities in every region improve evidently with increasing the *** tensile stress was simulated to be the largest at the corner,and the hot tearings were forecasted to mainly appear at the corner *** employing proper billet height and pressure,the extruded samples consisted of fine and uniform microstructures,and can obtain excellent mechanical properties and Brinell hardness.

关键词： A357 aluminum alloy inhomogeneity semi-solid state backward extrusion numerical simulation

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Microstructure and Mechanical Properties of backward-extruded Mg-Zn-xCa Biomaterials

Microstructure and Mechanical Properties of Backward-extrude...

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中国材料大会2012

作者： Xuejun Li Hui Li Shuangshuang Zhao Ning Ma Qiuming Peng State Key Laboratory of Metastable Materials Science and Technology Yanshan University

ISBN: (纸本)9783037856086

The Mg-1.0Zn-xCa （x=0.2, 0.5, 0.8, 1 wt. %） alloys were prepared by zone solidification and backward extrusion technology. The microstructure and mechanical properties of backward-extruded Mg-1.0Zn-xCa alloys were investigated. The results showed that these backward-extruded Mg-1.0Zn-xCa alloys were mainly composed of equi-axed pentagon-shaped grains and some Mg0.9Zn0.03 precipitates. The tensile and compressive strengths of backward-extruded Mg-1.0Zn-xCa alloys were greatly improved. The improved mechanical properties are mostly attributed to fine grain strengthening, solid solution strengthening and precipitate strengthening. The results demonstrated that the micro alloying of Ca element was one of effective method to improve the mechanical properties of Mg-1.0Zn based biomaterials.

关键词： Mg-1.0Zn-xCa alloys backward extrusion

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