In the industrial production, the dynamic cooling pre-aging treatment was employed to replace the isothermal pre-aging during the continuous heat treatment production of Al-Mg-Si alloy automotive sheets. The effects o...In the industrial production, the dynamic cooling pre-aging treatment was employed to replace the isothermal pre-aging during the continuous heat treatment production of Al-Mg-Si alloy automotive sheets. The effects of dynamic cooling pre-aging treatment on mechanical properties and paint-bake hardening behavior of an Al-Mg-Si alloy sheet are proposed in this study. 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 dynamic cooling pre-aging treatment at low temperature region led to the decreasing of cluster II, resulting in the deterioration of the ability of the paint-bake hardening. With the increase of the cooling pre-aging temperature, the increasing of cluster II effectively improved the stability against natural aging and the paint-bake hardening ability. The optimized dynamic cooling pre-aging temperature was ~150 ℃. In this condition, the hardness increase of the alloy sheet with pre-aging treatment is low during storage at room temperature. The high yield strength increment is obtained after paint-bake hardening.展开更多
The microstructural characteristics and paint-bake response of 6022 alloy with 0.3% Cu(mass fraction)were studied using optical microscope,scanning electron microscope(SEM),transmission electron microscope(TEM)and ten...The microstructural characteristics and paint-bake response of 6022 alloy with 0.3% Cu(mass fraction)were studied using optical microscope,scanning electron microscope(SEM),transmission electron microscope(TEM)and tensile tester.The results indicate that the phase constituents in the as-cast microstructure are Mg2Si,Si,Al5Cu2Mg8Si6,Al5FeSi,α-Al(MnCrFe)Si and CuAl2.During the following homogenization,CuAl2,Al5Cu2Mg8Si6 and Mg2Si phases are almost completely dissolved,and Al5FeSi transforms to α-Al(MnCrFe)Si particles.After rolling,the phase constituents in the alloy change less except the precipitation of Mg2Si particles,and the precipitation behavior of Mg2Si strongly depends on the thermomechanical conditions.Cu addition significantly increases the paint-bake response of 6022 alloy by facilitating the formation of β-" phase.Therefore,the tensile strength of 6022 alloy with 0.3% Cu is higher than that of 6022 alloy without Cu after paint-bake cycle.展开更多
采用硬度测试、室温拉伸、DSC分析、OM、SEM和TEM观察,研究复合添加微量Mn,Cr和Sr元素对汽车车身板用6016铝合金组织、时效硬化性与力学性能的影响。结果表明:添加Mn,Cr和Sr元素有效细化基体合金固溶后的再结晶晶粒并改变合金第二相的...采用硬度测试、室温拉伸、DSC分析、OM、SEM和TEM观察,研究复合添加微量Mn,Cr和Sr元素对汽车车身板用6016铝合金组织、时效硬化性与力学性能的影响。结果表明:添加Mn,Cr和Sr元素有效细化基体合金固溶后的再结晶晶粒并改变合金第二相的种类与分布。在6016合金中添加0.17%Mn+0.089%Cr+0.022%Sr(质量分数),对T4态塑性影响较小,但合金时效硬化速度、峰值硬度和时效态强度提高,模拟烤漆后屈服强度、抗拉强度分别提高27.8%和18.2%,屈服强度提高30 MPa。一方面Mn和Cr弥散相强化合金,另一方面Sr改变热力学平衡。并且Mn,Cr和Sr共同作用促进富铁相转变(β富铁相转变成α富铁相)使过剩Si含量增加,β″相析出激活能从105.7 k J/mol降至94.2 k J/mol,促进β″相弥散均匀析出,最终改善合金力学性能。展开更多
基金Project(2020YFF0218200) supported by the National Key R&D Program of China。
文摘In the industrial production, the dynamic cooling pre-aging treatment was employed to replace the isothermal pre-aging during the continuous heat treatment production of Al-Mg-Si alloy automotive sheets. The effects of dynamic cooling pre-aging treatment on mechanical properties and paint-bake hardening behavior of an Al-Mg-Si alloy sheet are proposed in this study. 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 dynamic cooling pre-aging treatment at low temperature region led to the decreasing of cluster II, resulting in the deterioration of the ability of the paint-bake hardening. With the increase of the cooling pre-aging temperature, the increasing of cluster II effectively improved the stability against natural aging and the paint-bake hardening ability. The optimized dynamic cooling pre-aging temperature was ~150 ℃. In this condition, the hardness increase of the alloy sheet with pre-aging treatment is low during storage at room temperature. The high yield strength increment is obtained after paint-bake hardening.
基金Project(2006KJA09)supported by Scientific and Technical Expansion Fund of China Aluminum Corporation
文摘The microstructural characteristics and paint-bake response of 6022 alloy with 0.3% Cu(mass fraction)were studied using optical microscope,scanning electron microscope(SEM),transmission electron microscope(TEM)and tensile tester.The results indicate that the phase constituents in the as-cast microstructure are Mg2Si,Si,Al5Cu2Mg8Si6,Al5FeSi,α-Al(MnCrFe)Si and CuAl2.During the following homogenization,CuAl2,Al5Cu2Mg8Si6 and Mg2Si phases are almost completely dissolved,and Al5FeSi transforms to α-Al(MnCrFe)Si particles.After rolling,the phase constituents in the alloy change less except the precipitation of Mg2Si particles,and the precipitation behavior of Mg2Si strongly depends on the thermomechanical conditions.Cu addition significantly increases the paint-bake response of 6022 alloy by facilitating the formation of β-" phase.Therefore,the tensile strength of 6022 alloy with 0.3% Cu is higher than that of 6022 alloy without Cu after paint-bake cycle.
文摘采用硬度测试、室温拉伸、DSC分析、OM、SEM和TEM观察,研究复合添加微量Mn,Cr和Sr元素对汽车车身板用6016铝合金组织、时效硬化性与力学性能的影响。结果表明:添加Mn,Cr和Sr元素有效细化基体合金固溶后的再结晶晶粒并改变合金第二相的种类与分布。在6016合金中添加0.17%Mn+0.089%Cr+0.022%Sr(质量分数),对T4态塑性影响较小,但合金时效硬化速度、峰值硬度和时效态强度提高,模拟烤漆后屈服强度、抗拉强度分别提高27.8%和18.2%,屈服强度提高30 MPa。一方面Mn和Cr弥散相强化合金,另一方面Sr改变热力学平衡。并且Mn,Cr和Sr共同作用促进富铁相转变(β富铁相转变成α富铁相)使过剩Si含量增加,β″相析出激活能从105.7 k J/mol降至94.2 k J/mol,促进β″相弥散均匀析出,最终改善合金力学性能。
