The influence of zirconium on the resistance to high temperature softening of 6082 Al-Mg-Si alloys has been researched. The softening process of 6082 alloys with Zr and without Zr, isothermally conditioned at 250°...The influence of zirconium on the resistance to high temperature softening of 6082 Al-Mg-Si alloys has been researched. The softening process of 6082 alloys with Zr and without Zr, isothermally conditioned at 250°C, has been investigated. The results show the inclusion of Zr inhibits the decrease of HB in hardness(HB) compared with the alloys without Zr. This is due to the Zr and Al forming coherent dispersoid-A!3Zr, and Al3Zr particles within an Al matrix, which effectively restricts grain boundary movement. A study is also carried out to investigate the changes in resistivity, which occurs during the ageing of alloys containing Zr, compared to those without Zr. It is found that in both cases there is an initial rapid rise in resistivity followed by a slower rise in resistivity as ageing proceeds. The value of resistivity is lower for 6082 alloys with Zr compared with 6082 alloys without Zr; this is explained in terms of the role of Zr in the 6082 alloys.展开更多
The dynamic mechanical behavior of Al-Mg-Si alloy was investigated under different strain rates by mechanical property and microstructure characterization,constitutive behavior analysis and numerical simulation in the...The dynamic mechanical behavior of Al-Mg-Si alloy was investigated under different strain rates by mechanical property and microstructure characterization,constitutive behavior analysis and numerical simulation in the present study.As the strain rate increases,the yield strength,ultimate tensile strength and elongation increase first,then remain almost constant,and finally increase.The alloy always exhibits a typical ductile fracture mode,not depending on the strain rate.However,as the strain rate increases,the number of dimples gradually increases.Tensile deformation can refine grains,however,the grain structure is slightly affected by the strain rate.An optimized Johnson-Cook constitutive equation was used to describe the mechanical behavior and obtained by fitting the true stress-strain curves.The parameter C was described by a function related to the strain rate.The fitting true stress-strain curves by the JC model agree very well with the experimental true stress-strain curves.The true stress-strain curves calculated by the finite element numerical simulation agree well with the experimental true stress-strain curves.展开更多
The microstructure evolution and precipitation behavior of Al-Mg-Si alloy during initial aging were studied using hardness testing, conductivity testing, differential scanning calorimetry(DSC), and high resolution tra...The microstructure evolution and precipitation behavior of Al-Mg-Si alloy during initial aging were studied using hardness testing, conductivity testing, differential scanning calorimetry(DSC), and high resolution transmission electron microscopy(HRTEM). The results show that the precipitation sequence of the Al-Mg-Si alloy during initial aging can be represented as: supersaturated solid solution → spherical Mg/Si clusters → needle-like Guinier Preston(GP) zone → β″. Clusters are completely coherent with the Al matrix. The GP zone with relatively complete independent lattice parameters that differ slightly from the Al matrix parameters, is oriented along the direction of <111>Aland lying on {111}Alplane. The strength of the Al-Mg-Si alloy is greatly enhanced by the threedimensional strain field that exists between the β″ phase and the two {200}Alplanes. After aging at 170 ℃ for 6 h, the hardness reaches the peak of 127 HV and remains for a long time. At this stage, the electrical conductivity keeps relatively stable due to the formation of coherent precipitates(Mg/Si clusters/GP zones) and the reduction in solute atom concentration in the Al matrix. The severe coarsening and decreased number density of the β″ phase during the over-aging stage result in a significant decrease in the hardness.展开更多
The surface modification on the AA6082 Al?Mg?Si aging-hardenable aluminum alloy was investigated by electricaldischarge alloying (EDA) process. Kerosene, used as a dielectric fluid, was pyrolytically decomposed into c...The surface modification on the AA6082 Al?Mg?Si aging-hardenable aluminum alloy was investigated by electricaldischarge alloying (EDA) process. Kerosene, used as a dielectric fluid, was pyrolytically decomposed into carbon for the formationof a self-lubricated carbide layer on the aluminum alloy surface during EDA process. Transmission electron microscopy (TEM)image found that the self-lubricated carbide layer was a multi-phase material with carbides and graphite. As a result, theEDA-modified aluminum alloy had a negligible wear rate of ~2?10?4 mg/m (c. f. ~1.1?10?2 mg/m for aluminum alloy substrate).Notably, a new characteristic was found that the EDA-processed carbide layer was a soft magnet, which improved theelectromagnetic interference (EMI) shielding performance of the alloy.展开更多
The study investigates the effects of pre-strain on the bake hardenability and precipitation behavior of Al-Mg-Si automotive body sheets. The scanning electron microscopy, transmission electron microscopy, tensile tes...The study investigates the effects of pre-strain on the bake hardenability and precipitation behavior of Al-Mg-Si automotive body sheets. The scanning electron microscopy, transmission electron microscopy, tensile test, Vickers hardness test, and differential scanning calorimetry were conducted for the purpose. It was found that the pre-strain treatment partially inhibits the natural aging hardening effect but cannot completely eliminate it. The pre-straining significantly enhances the bake hardening effect, with the 5% pre-strain sample showing the highest increase in yield strength and hardness. The formation of fine β" precipitates and dislocation structures contribute to the observed strengthening. Additionally, the study highlights the importance of optimizing pre-strain levels to achieve the best balance between strength and ductility in bake-hardened aluminum alloys.展开更多
基金the Scientificand Technical Commission Fund of Shanghai
文摘The influence of zirconium on the resistance to high temperature softening of 6082 Al-Mg-Si alloys has been researched. The softening process of 6082 alloys with Zr and without Zr, isothermally conditioned at 250°C, has been investigated. The results show the inclusion of Zr inhibits the decrease of HB in hardness(HB) compared with the alloys without Zr. This is due to the Zr and Al forming coherent dispersoid-A!3Zr, and Al3Zr particles within an Al matrix, which effectively restricts grain boundary movement. A study is also carried out to investigate the changes in resistivity, which occurs during the ageing of alloys containing Zr, compared to those without Zr. It is found that in both cases there is an initial rapid rise in resistivity followed by a slower rise in resistivity as ageing proceeds. The value of resistivity is lower for 6082 alloys with Zr compared with 6082 alloys without Zr; this is explained in terms of the role of Zr in the 6082 alloys.
基金Funded by the National Key Laboratory of Shock Wave and Detonation Physics(No.JCKYS2023212005)the National Science Foundation of China(Nos.11972202 and 52005271)+2 种基金the State Key Laboratory for Advanced Metals and Materials(No.2023-Z04)the Major Project of Ningbo Science and Technology Innovation 2025(Nos.2021Z099 and 2023Z005)the K C Wong Magna Fund from Ningbo University。
文摘The dynamic mechanical behavior of Al-Mg-Si alloy was investigated under different strain rates by mechanical property and microstructure characterization,constitutive behavior analysis and numerical simulation in the present study.As the strain rate increases,the yield strength,ultimate tensile strength and elongation increase first,then remain almost constant,and finally increase.The alloy always exhibits a typical ductile fracture mode,not depending on the strain rate.However,as the strain rate increases,the number of dimples gradually increases.Tensile deformation can refine grains,however,the grain structure is slightly affected by the strain rate.An optimized Johnson-Cook constitutive equation was used to describe the mechanical behavior and obtained by fitting the true stress-strain curves.The parameter C was described by a function related to the strain rate.The fitting true stress-strain curves by the JC model agree very well with the experimental true stress-strain curves.The true stress-strain curves calculated by the finite element numerical simulation agree well with the experimental true stress-strain curves.
基金financially supported by the Research Foundation of Education Bureau Hunan Province,China (Grant No. 22C0598)。
文摘The microstructure evolution and precipitation behavior of Al-Mg-Si alloy during initial aging were studied using hardness testing, conductivity testing, differential scanning calorimetry(DSC), and high resolution transmission electron microscopy(HRTEM). The results show that the precipitation sequence of the Al-Mg-Si alloy during initial aging can be represented as: supersaturated solid solution → spherical Mg/Si clusters → needle-like Guinier Preston(GP) zone → β″. Clusters are completely coherent with the Al matrix. The GP zone with relatively complete independent lattice parameters that differ slightly from the Al matrix parameters, is oriented along the direction of <111>Aland lying on {111}Alplane. The strength of the Al-Mg-Si alloy is greatly enhanced by the threedimensional strain field that exists between the β″ phase and the two {200}Alplanes. After aging at 170 ℃ for 6 h, the hardness reaches the peak of 127 HV and remains for a long time. At this stage, the electrical conductivity keeps relatively stable due to the formation of coherent precipitates(Mg/Si clusters/GP zones) and the reduction in solute atom concentration in the Al matrix. The severe coarsening and decreased number density of the β″ phase during the over-aging stage result in a significant decrease in the hardness.
文摘The surface modification on the AA6082 Al?Mg?Si aging-hardenable aluminum alloy was investigated by electricaldischarge alloying (EDA) process. Kerosene, used as a dielectric fluid, was pyrolytically decomposed into carbon for the formationof a self-lubricated carbide layer on the aluminum alloy surface during EDA process. Transmission electron microscopy (TEM)image found that the self-lubricated carbide layer was a multi-phase material with carbides and graphite. As a result, theEDA-modified aluminum alloy had a negligible wear rate of ~2?10?4 mg/m (c. f. ~1.1?10?2 mg/m for aluminum alloy substrate).Notably, a new characteristic was found that the EDA-processed carbide layer was a soft magnet, which improved theelectromagnetic interference (EMI) shielding performance of the alloy.
文摘The study investigates the effects of pre-strain on the bake hardenability and precipitation behavior of Al-Mg-Si automotive body sheets. The scanning electron microscopy, transmission electron microscopy, tensile test, Vickers hardness test, and differential scanning calorimetry were conducted for the purpose. It was found that the pre-strain treatment partially inhibits the natural aging hardening effect but cannot completely eliminate it. The pre-straining significantly enhances the bake hardening effect, with the 5% pre-strain sample showing the highest increase in yield strength and hardness. The formation of fine β" precipitates and dislocation structures contribute to the observed strengthening. Additionally, the study highlights the importance of optimizing pre-strain levels to achieve the best balance between strength and ductility in bake-hardened aluminum alloys.
