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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。
A 2.7 mm thick 5083-O aluminum alloy sheet was friction stir-treated (FSP) at various head shoulder diameters, rotational speeds, and travel speeds. The research shows that the material undergoes dynamic recrystallization during the process of friction stir processing, and the grains in the processing zone are obviously refined. With the increase of shoulder diameter and rotation speed of the mixing head, the grain size in the working zone gradually increases; as the traveling speed increases, the grain size decreases. By friction stir processing, processing zone performance is improved. When using a large shoulder diameter (16 mm) low travel speed, the lowest tensile strength of the processing zone, and the base metal is equivalent. With the reduction of shoulder diameter and rotation speed of the mixing head, the tensile strength of the processing zone increases, the highest strength reaches up to 108% of the base material and the elongation rate is about 123% of the base material. In addition, the formation mechanism and the performance difference of light and dark arc in the processing area were studied. The analysis shows that the grain size of the dark arc area is smaller, the Mg atom content is higher, the dislocations are more and the hardness is higher than that of the internal light arc area, and the difference of the internal hardness varies with the increase of heat input The decrease, large heat input is conducive to improving the processing zone organization and performance uniformity.