不同轧制工艺对纯锡微观组织与性能的影响

Effects of Different Rolling Processes on Microstructure and Properties of Pure Tin

摘要:

本文系统研究多晶纯锡(99.99%)在不同轧制工艺下的显微组织演变和力学行为，阐明纯锡在不同轧制状态下晶粒细化规律，以期为调控与优化纯锡的强韧化奠定理论基础。研究结果表明，不同轧制工艺对纯锡的微观组织和力学性能影响明显，其中轧制速度是影响纯锡的晶粒细化和力学性能提升的最主要因素，温度、速度和路径通过调控变形过程中的孪晶激发以及孪晶诱导再结晶的进程而实现不同工艺下的晶粒细化。轧制过程晶粒细化机制为：变形初期诱发60°<100>形变孪晶，在后续变形过程中孪晶逐渐演变为再结晶条带状组织，分割细化晶粒，且孪晶和再结晶组织的随机取向弱化原始粗晶产生的集中织构。轧制变形能明显提高纯锡的强度，且单向轧制工艺下的纯锡样品的TD方向的屈服强度和抗拉强度明显高于RD方向。

Abstract:

Pure tin (β-Sn) has attracted significant attention due to its excellent chemical properties and plasticity. It is widely used in many fields as solder material and coating material. Presently, there are relatively few investigations on the grain refinement behavior and strength toughness strengthening mechanism of bulk polycrystalline pure tin during rolling. In this work, the evolution of microstructure and mechanical properties and the grain refinement law of polycrystalline pure tin (99.99%) under different rolling processes are studied, which is expected to lay a theoretical foundation for adjusting and optimizing the strengthening and toughening properties of pure tin. The results show that different rolling processes have obvious effects on the microstructure and properties of pure tin. The process of twin excitation and twin induced recrystallization in the deformation process are realized by regulating the factors of temperature, speed and path in the rolling process, in which the rolling speed is the most important factor. The grain refinement mechanism of rolling process is as follows: 60°<100> deformation twins are induced at the initial stage of deformation, and the twins gradually evolve into recrystallized banded structure and divide and refine grains in the subsequent deformation process. Recrystallized grains and twins usually randomize the texture and therefore weaken the concentrated texture produced by the original coarse grain. Rolling deformation can significantly increase the strength of pure tin. The yield strength and tensile strength in TD direction are significantly higher than that in RD direction under unidirectional rolling.