Kittner Kristina, Ullmann Madlen, Prahl Ulrich
Institute of Metal Forming, Technische Universität Bergakademie Freiberg, Bernhard-von-Cotta-Straße 4, 09599 Freiberg, Germany.
Materials (Basel). 2021 Jun 29;14(13):3628. doi: 10.3390/ma14133628.
The Mg-6.8Y-2.5Zn-0.4Zr (WZ73) alloy exhibits different microstructure characteristic after conventional casting compared to the twin-roll cast (TRC) state. Twin-roll casting results in a finer microstructure, where the LPSO phases are more finely distributed and less strongly connected. A transfer of the hot deformation behavior from the as-cast condition to the TRC condition is only possible to a limited extent due to the microstructural differences. Both states show differences in the recrystallization behavior during hot deformation. In the conventional cast state, dynamic recrystallization (DRX) is assumed to be delayed by the occurrence of coarse blocky LPSO phases. Main DRX mechanisms are continuous dynamic recrystallization (CDRX), particle stimulated nucleation (PSN) and twin induced dynamic recrystallization (TDRX). The deformed TRC sample showed pronounced DRX at almost all deformation conditions. Besides the TDRX and the PSN mechanism, kink induced dynamic recrystallization (KDRX) can be observed. Optimum deformation conditions for both states are temperatures from 500 °C to 520 °C, and strain rates ranging from 0.01 s to 0.1 s for the as-cast material as well as a strain rate of 1 s for the TRC material.
与双辊铸态（TRC）相比，Mg-6.8Y-2.5Zn-0.4Zr（WZ73）合金在常规铸造后呈现出不同的微观结构特征。双辊铸造导致更精细的微观结构，其中长周期堆叠有序（LPSO）相分布更细且连接较弱。由于微观结构差异，热变形行为仅在有限程度上从铸态转移到TRC态。两种状态在热变形过程中的再结晶行为都存在差异。在常规铸态下，粗大块状LPSO相的出现被认为会延迟动态再结晶（DRX）。主要的DRX机制是连续动态再结晶（CDRX）、粒子激发形核（PSN）和孪晶诱发动态再结晶（TDRX）。变形后的TRC样品在几乎所有变形条件下都表现出明显的DRX。除了TDRX和PSN机制外，还可以观察到扭折诱发动态再结晶（KDRX）。两种状态的最佳变形条件是铸态材料温度为500℃至520℃，应变速率为0.01s⁻¹至0.1s⁻¹，TRC材料的应变速率为1s⁻¹。
