搅拌摩擦加工5083-O铝合金的组织和性能

Friction Stir Processing in 5083-O Aluminum Alloy: Microstructures and Mechanical Properties

在不同的搅拌头轴肩直径、旋转速度及行进速度下,对2.7 mm厚5083-O铝合金薄板进行了搅拌摩擦加工处理(FSP)。研究表明,材料在搅拌摩擦加工过程中发生动态再结晶,加工区晶粒得到明显的细化。随着搅拌头的轴肩直径和旋转速度的增加,加工区晶粒尺寸逐渐增大;随着行进速度的增加,晶粒尺寸减小。通过搅拌摩擦加工处理,加工区性能得到改善。当采用大轴肩直径(16 mm)低行进速度时,加工区抗拉强度最低,与母材相当。随着搅拌头轴肩直径和旋转速度的减小,加工区抗拉强度上升,最高强度可达母材的108%,延伸率约为母材的123%。此外,研究了加工区内部明暗弧纹的形成机制和其性能差异。分析表明,与内部浅色弧纹区域相比,深色弧纹区域晶粒尺寸更小,Mg原子含量更高,位错更多,硬度也更高,其内部硬度差异随热输入量的增加而减小,大热输入量有利于提高加工区组织和性能的均匀性。

5083-O aluminum alloy sheets with thickness of 2 mm were subjected to friction stir processing（ FSP）,and the effect of processing parameters on the microstructures and mechanical properties was investigated. Fine equiaxed dynamically recrystallized grains were observed in the FSP zone. As the diameter of the shoulder and rotation speed increased,the grains got coarsened. However,with the increase of the moving speed,the size of the grains decreased. At a low moving speed and a 16 mm-diameter shoulder,the ultimate tensile strength was the lowest,which was similar to that of the base metal. As the diameter of the shoulder decreased and the moving speed increased,the tensile strength increased and the ultimate value could reach to 108% of that of the base metal. The elongation of the FSP zone was 123% of that of the base metal. Besides,the arc patterns in the FSP zone were also researched. Smaller grains,more Mg atoms and dislocations were observed in dark arc patterns,resulting in higher hardness. And the fluctuation of the hardness decreased with increasing heat input,which indicated that high heat input was beneficial for elevating the homogeneousness of the FSP zone.