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Mechanical properties and microstructure of an α+β titanium alloy with high strength and fracture toughness

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Rare Metals 2009年第4期28卷 346-349页

作者： YU Yang HUI Songxiao YE Wenjun xiong baiqing State Key Laboratory for Fabrication and Processing of Nonferrous Metals General Research Institute for Nonferrous Metals Beijing 100088 China

The Ti-Al-Sn-Zr-Cr-Mo-V-Si （Ti-62A） alloy, an alpha-beta alloy with high strength and fracture toughness, is currently used as an advanced structural material in aerospace and non-aerospace applications. Thermo-mechanical processes can be used to optimize the relationship between its strength and fracture toughness. A Ti-62A alloy bar can be machined through a transus β-forged plus α＋β solution treated and aged specimen with a lamellar alpha microstructure. The effects of heat treatment on the mechanical properties were discussed. Heat treatment provided a practical balance of strength, fracture toughness, and fatigue crack growth resistance. A comparison of the Ti-62A alloy with the Ti-62222S alloy under the same thermo-mechanical processing conditions showed that their properties are at the same level.

关键词： titanium alloys mechanical properties strength toughness fatigue crack growth rate

Elevated temperature endurance and creep properties of extruded 2D70 Al alloy rods

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Rare Metals 2011年第3期30卷 310-315页

作者： WANG Guojun xiong baiqing ZHANG Yong＇an LI Zhihui State Key Laboratory of Nonferrous Metals and Processes General Research Institute for Nonferrous Metals Beijing 100088 China Northeast Light Alloy Co. Ltd. Harbin 150060 China

The elevated temperature performances of 2D70 Al alloy hot extrusion rods after two-stage homogenization and intensive deformation were studied by measuring the elevated temperature enduring strength and the creep ultimate strength. The fracture morphology of some selected samples after testing at different elevated temperatures was observed by scanning electron microscopy （SEM）. The results indicate that, as the test temperature increases, the elevated temperature enduring strength of 2D70 Al alloy decreases gradually. In a comparison between 150 C and 240 C, the notch enduring strength drops from 375 to 185 MPa and the smooth enduring strength drops from 337 to 130 MPa. Enduring strength is not sensitive to the notch. The notch sensitivity ratio （NSR） coefficient is in the range of 1.119 to 1.423 from 150 C to 240 C. The creep test results show that, as the test temperature increases from 150 C to 240 C, the creep ultimate strength of 2D70 Al alloy rods drops gradually from 312 to 117 MPa.

关键词： aluminum alloys high temperature properties strength of materials creep notched bar tensile testing

Effects of the two-step ageing treatment on the microstructure and properties of 7B04 alloy pre-stretched thick plates

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Rare Metals 2007年第3期26卷 193-199页

作者： LI Zhihui xiong baiqing ZHANG Yong ＇an ZHU Baohong WANG Feng LIU Hongwei State Key Laboratory for Fabrication and Processing of Nonferrous Metals General Research Institute for Nonferrous Metals Beijing 100088 China

The effects of the two-step ageing parameters （temperature and time） on the mechanical properties and electrical conductivity of 7B04 （A1-Zn-Mg-Cu） pre-stretched thick plates were studied. The results reveal that the initial T1 ageing contributes a major increase of the tensile strength, and the 0.2% proof stress value reaches 482 MPa after ageing for 7 h at 115℃. Behavioral differences in the tensile properties of the alloy after the two-step ageing treatment were less with the first-step ageing at 115~C for different time periods （7, 14, and 21 h）. The effects of the second ageing parameters on the properties and microstructure of the 7B04 alloy were remarkable. TEM analysis of the samples aged at Temper I （7 h at 115℃ ＋ 12 h at 160℃） and Temper II （7 h at 115℃ ＋ 16 h at 165℃） indicates that two kinds of phases, i.e. 11＇ and 11 phases, precipitate from the matrix and efficiently improve the tensile strength of the alloy, and the grain boundary precipitates are coarse and discrete. There are obvious precipitate free zones （PFZs） along the grain boundary in the microstructure of the alloy after the two-step ageing treatment.

关键词： 7B04 alloy two-step ageing mechanical properties electrical conductivity microstructure

Residual stress with asymmetric spray quenching for thick aluminum alloy plates

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International Journal of Minerals,Metallurgy and Materials 2023年第11期30卷 2200-2211页

作者： Ning Fan Zhihui Li Yanan Li Xiwu Li Yongan Zhang baiqing xiong State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co.Ltd.Beijing 100088China GRIMAT Engineering Institute Co. Ltd.Beijing 101407China General Research Institute for Nonferrous Metals Beijing 100088China

Solution and quenching heat treatments are generally carried out in a roller hearth furnace for large-scale thick aluminum alloy ***,the asymmetric or uneven spray water flow rate is inevitable under industrial production conditions,which leads to an asymmetric residual stress *** spray quenching treatment was conducted on self-designed spray equipment,and the residual stress along the thickness direction was measured by a layer removal method based on *** the asymmetric spray quenching condition,the subsurface stress of the high-flow rate surface was lower than that of the low-flow rate surface,and the difference between the two subsurface stresses increased with the increase in the difference in water flow *** subsurface stress underneath the surface with a water flow rate of 0.60 m^(3)/h was 15.38 MPa less than that of 0.15 m^(3)/*** simulated residual stress by finite element(FE)method of the high heat transfer coefficient(HTC)surface was less than that of the low HTC surface,which is consistent with the experimental *** FE model can be used to analyze the strain and stress evolution and predict the quenched stress magnitude and distribution.

关键词： aluminum alloy spray quenching residual stress layer removal method finite element method

PREPARATION OF ROUND BILLETS BY SPRAY FORMING TECHNOLOGY

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中国有色金属学会会刊：英文版 1999年第2期9卷 98-102页

作者： xiong, baiqing Zhang, Yong'an Lin, Yaojun Zhang, Shaoming Shi, Likai Beijing General Research Inst for Nonferrous Metals Beijing China

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１ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｓｐｒａｙｆｏｒｍｉｎｇｔｅｃｈｎｏｌｏｇｙｉｓａｎｅｗｔｅｃｈｎｏｌｏｇｙｆｏｒｍａｋｉｎｇｍａｔｅｒｉａｌｓ．Ｉｔｈａｓｂｅｅｎｄｅｖｅｌｏｐｅｄｏｎｔｈｅｂａｓｉｓｏｆｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｒａｐｉｄｓ...

关键词： spray forminground billetsnumerical methodratio of gas flux to melt flux

Structural evolution of spray-formed Al-70wt.%Si alloys during iso-thermal holding in the semi-solid state

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Rare Metals 2005年第4期24卷 317-324页

作者： ZHANG Di CUI Hua WEI Yanguang ZHANG Jishan ZHANG Yongan xiong baiqing The State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China General Research Institute for Nonferrous Metals Beijing 100088 China

The grain growth behavior of spray-formed Al-70wt.%Si alloys was studied in the semi-solid state. The specimens were isothermally heat-treated at various temperatures between the solidus and liquidus of Al-Si alloys and then quenched in water. The microstructure of reheated specimens was characterized using optical and scanning electron microscopies. The isothermal holding experiment was carried out to investigate grain growth behavior as a function of holding time and temperature in the semi-solid state. The coarsening mechanism and the effect of porosity on microstructure were also studied.

关键词： materials science grain growth behavior spray forming Al-70wt.%Si alloys semi-solid processing

Ageing behavior of an Al-Zn-Mg-Cu alloy pre-stretched thick plate

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Journal of University of Science and Technology Beijing 2007年第3期14卷 246-250页

作者： Zhihui Li baiqing xiong Yongan Zhang Baohong Zhu Feng Wang Hongwei Liu State Key Laboratory for Fabrication and Processing of Non-ferrous Metals General Research Institute for Non-ferrous Metals Beijing 100088 China

The ageing behavior of a pre-stretched thick plate of Al-Zn-Mg-Cu alloy was systemically studied including one-step ageing, two-step ageing, and retrogression and reageing treatment （RRA）. One-step ageing of the alloy resulted in peak ultimate tensile strengths of 595 and 575 MPa after 22 and 6 h at 120 and 135°C, respectively. The strengthening phase in peak aged （T6 temper） alloy contained GP zones and the η′ phase predominantly. After two-step ageing, the electrical conductivity was increased markedly, but the pre-stretched thick plate sacrificed a great loss of strength. RRA treatment provided a method for maintaining the strength close to that obtained by T6 temper and for obtaining the high electrical conductivity close to that obtained by T7 temper; the ultimate tensile strength and electrical conductivity were 583 MPa and 21.0 MS/m, respectively. TEM analysis of T7 and RRA specimens revealed two types of precipitates that contributed to age strengthening i.e. the η′ and η phases.

关键词： Al-Zn-Mg-Cu alloy pre-stretched thick plate ageing tensile properties precipitation

Effect of P/M value on the preforms and microstructures of spray formed 70Si30Al alloy

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Journal of University of Science and Technology Beijing 2007年第2期14卷 141-145页

作者： Yanguang Wei baiqing xiong Yongan Zhang Hongwei Liu Feng Wang Baohong Zhu State Key Laboratory for Fabrication ＆ Processing of Nonferrous Metals Beijing General Research Institute for Nonferrous Metals Beijing 100088 China

A novel 70Si30Al alloy was prepared by the spray forming process for electronic packaging materials. The effect of the ratio of atomization pressure to metal melt mass flux rate （P/M） on the preforms and microstructures of the spray-deposited 70Si30Al alloy was studied. The results indicate that the PIM value has a considerable influence on the formation of the preforms and the optimal value is in the range of 0.209-0.231 MPa/（***^-1）. The microstructure of the spray formed 70Si30AI alloy is fine and homogenous. The primary silicon phases distributing in the aluminum matrix evenly are fine and irregular. The aluminum matrix is divided into two groups： supersaturated α-Al phase or α-Al phase and Al-Si pseudoeutectic phase or Al-Si eutectic phase.

关键词： 70Si30Al alloy spray forming atomization pressure mass flux rate microstructure

Microstructure and properties characteristic during interrupted multi-step aging in Al-Cu-Mg-Ag-Zr alloy

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Rare Metals 2011年第4期30卷 419-423页

作者： ZHUBaohong xiong baiqing ZHANG Yong＇an ZHANG Jianbo WANG Feng LI Zhihui State Key Laboratory of Nonferrous Metals and Processes General Research Institute for Nonferrous Metals Beijing 100088 China

The effects of interrupted multi-step aging on the microstructure and properties of A1-Cu-Mg-Ag-Zr alloy were studied by tensile, hardness, electrical conductivity tests and transmission electron microscopy （TEM）. Interrupted multi-step aging delayed the peak aging time compared to one-step aging and kept the same levels of hardness, electrical conductivity, ultimate tensile strength （UTS）, yield strength （YS） and elongation as those of the T6 temper alloy while increased the fracture toughness notably. Ω phase and a little θ＇ phase precipitated and grew simultaneously in the process of one-step aging at 160℃. During the second-step aging at 65℃ of interrupted multi-step aging, no TEM characteristic of Ω precipitates could be found. During the third step of interrupted multi-step aging, Ω began to dominate the microstructure like what happened in the process of one-step aging. The difference of properties between the T6 temper and the interrupted multi-step aged alloys might be related to the different precipitation sequences in the process of the two heat treatment technologies.

关键词： aluminum copper alloys heat treatment microstructure fracture toughness aging