ABSTRACT The microstructure evolution for different post-homogenisation cooling rates and the flow stress behaviour in direct chill cast AA6060 alloys were studied. Results revealed that decreasing cooling rates reduced the flow stress owing to the precipitation of Mg2Si and reduction of the solid solution level. Micro-alloying of Mn generated a distribution of α-Al(FeMn)Si dispersoids during the homogenisation, with the size and number density decreasing at higher homogenisation temperatures. TEM studies confirmed that the dispersoids acted as favourable nucleation sites for Mg2Si and significantly promoted the precipitation of Mg2Si during subsequent cooling. The high-temperature flow stress was controlled by the solid solution levels of Mg, Si, and Mn resulting from the interaction between dispersoids and Mg2Si. The combination of the Mn addition, a low cooling rate, and a low homogenisation temperature provided the lowest flow stress, which improved the hot workability of the alloy and promoted ready dissolution of Mg2Si during extrusion.

中文翻译：

---

均质后冷却速度和Mn添加量对AA6060合金Mg2Si析出和热加工性的影响

摘要 研究了不同均质化后冷却速率的微观结构演变和直接冷铸 AA6060 合金的流动应力行为。结果表明，由于 Mg2Si 的析出和固溶体水平的降低，降低冷却速度降低了流动应力。Mn 的微合金化在均质化过程中产生了 α-Al(FeMn)Si 弥散体的分布，在更高的均质化温度下，尺寸和数量密度会降低。TEM 研究证实，弥散体作为 Mg2Si 的有利成核位点，并在随后的冷却过程中显着促进了 Mg2Si 的析出。高温流变应力由弥散体和 Mg2Si 之间相互作用产生的 Mg、Si 和 Mn 的固溶体水平控制。