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
Effects of additions of trace Sn on the bake-hardening responses of a pre-aged Al-0.85 Mg-0.85 Si(in wt%)alloy were investigated through mechanical tests,differential scanning calorimetry,electrical resistivity and tr...Effects of additions of trace Sn on the bake-hardening responses of a pre-aged Al-0.85 Mg-0.85 Si(in wt%)alloy were investigated through mechanical tests,differential scanning calorimetry,electrical resistivity and transmission electron microscopy.Results indicate that trace Sn additions reduced the number density of pre-aging clusters by inhibiting the formation of unstable counterpart during pre-aging treatment,leading to low strength and high supersaturation of solute atoms.In a subsequent paint-bake treatment,the presence of highly supersaturated solute atoms and high concentrated free vacancies moderated the activation energy barrier ofβ’’phase and thus kinetically accelerated the formation ofβ’’.Consequently,the trace Sn additions enhanced the bake-hardening responses of the pre-aged alloys significantly.The Sn-containing pre-aged Al-Mg-Si alloys with low strength and great bake-hardening responses hold promising potential for automotive body skin applications.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financially supported by the National Key R&D Program of China(No.2018YFB2001800).
文摘Effects of additions of trace Sn on the bake-hardening responses of a pre-aged Al-0.85 Mg-0.85 Si(in wt%)alloy were investigated through mechanical tests,differential scanning calorimetry,electrical resistivity and transmission electron microscopy.Results indicate that trace Sn additions reduced the number density of pre-aging clusters by inhibiting the formation of unstable counterpart during pre-aging treatment,leading to low strength and high supersaturation of solute atoms.In a subsequent paint-bake treatment,the presence of highly supersaturated solute atoms and high concentrated free vacancies moderated the activation energy barrier ofβ’’phase and thus kinetically accelerated the formation ofβ’’.Consequently,the trace Sn additions enhanced the bake-hardening responses of the pre-aged alloys significantly.The Sn-containing pre-aged Al-Mg-Si alloys with low strength and great bake-hardening responses hold promising potential for automotive body skin applications.
