It is known that Al added to the Zn coating layer of hot-dip galvanized steel sheets (HDG) diffuses to the surface at room temperature and forms Al-based oxides in air. In order to understand the diffusion behavior of Al in Zn coating layer, this study investigated the effect of the aging temperature on the segregation behavior of Al-based oxides in HDG with and without temper rolling (skinpass rolling) using a material with a Zn coating weight of about 56 g/m² with an Al content of approximately 0.20 mass%. The specimens were aged at −15, 5, 20, 38, 100 or 200°C in air after production, and the surface and cross sections were observed and analyzed by XRF, SEM-EDX, EBSD and TEM. As a result, up to the aging temperature of 38°C, the amount of Al-based oxides increased linearly to the square root of aging time, suggesting that the formation rate is determined by the diffusion of Al in Zn coating layer in this temperature range. However, this linear relationship did not hold at aging temperatures above 100°C. In addition, in the temper-rolled HDG, the formation rate of Al-based oxides is larger than that without temper rolling up to the aging temperature of 38°C, and then decreased drastically at aging temperatures above 100°C. The segregation behavior of Al-based oxides is discussed in view of the diffusion behavior of Al and the changes in the macrostructure of the Zn coating layer during the aging after production.

众所周知，添加到热浸镀锌钢板 (HDG) 的 Zn 涂层中的 Al 在室温下会扩散到表面并在空气中形成 Al 基氧化物。为了了解 Al 在 Zn 涂层中的扩散行为，本研究使用具有 Zn 涂层的材料研究了时效温度对 HDG 中铝基氧化物偏析行为的影响。重量约 56 g/m ²铝含量约为 0.20 质量％。试样制作完成后在-15、5、20、38、100或200℃空气中进行时效处理，采用XRF、SEM-EDX、EBSD和TEM对表面和截面进行观察和分析。结果表明，时效温度达到 38°C 时，Al 基氧化物的数量呈线性增加至时效时间的平方根，表明该温度下 Al 在 Zn 涂层中的扩散决定了形成速率范围。然而，这种线性关系在 100°C 以上的老化温度下不成立。此外，在回火轧制热镀锌中，Al基氧化物的形成速率在时效温度达到38℃时比未进行回火轧制时大，然后在时效温度超过100℃时急剧下降。