ABSTRACT

Friction stir processing (FSP) is an effective technique in microstructural refinement. It is expected to make a great change in the manufacturing industries. However, the weak region of thermo-mechanically affected zone (TMAZ) limits the practical application of FSP. Hence, double-sided FSP (DFSP) was proposed to eliminate such weak zone. In this work, 7050-T7451 alloy plates were processed by the single-sided FSP (SFSP) and DFSP (two parameters: DFSP-0O-50D and DFSP-30O-35D). The DFSP-30O-35D parameters can ensure the overlapping of the former and later stir pin, which prepared the refined and homogeneous microstructure without TMAZ, and result in a significant enhancement of mechanical properties. In the former SZ, the main precipitates are Al₂CuMg and η (MgZn₂) phase; in the later SZ, the main precipitates are η′ phase with smaller size and higher quantity. It caused a higher microhardness of the later SZ than the former ones.

摘要

摩擦搅拌加工（FSP）是一种有效的微结构细化技术。预计制造业将发生巨大变化。然而，热机械影响区（TMAZ）的薄弱区域限制了FSP的实际应用。因此，提出了双面FSP（DFSP）来消除这种薄弱区。在这项工作中，7050-T7451合金板采用单面FSP（SFSP）和DFSP（两个参数：DFSP-0O-50D和DFSP-30O-35D）进行加工。DFSP-30O-35D参数可以确保前后搅拌针的重叠，在没有TMAZ的情况下制备了精细均匀的微观结构，并显着提高了力学性能。在前 SZ 中，主要析出物为 Al ₂ CuMg 和 η (MgZn ₂） 阶段; 在后期SZ中，主要析出物为尺寸较小、数量较多的η′相。它导致后期 SZ 的显微硬度高于前者。