Abstract 5456-H112 aluminum alloy plates with a thickness of 20 mm were joined using floating-bobbin tool friction stir welding at different travel speeds from 28 to 160 mm/min and a fixed rotational speed of 90 rpm. The results of microstructural analysis indicated that the grain size is decreased at a constant travel speed (at each of the speeds of 28, 40, 56, 80, 112, and 160 mm/min), from the retreating side to the advancing side of the joints whereas the density and the size of the intermetallic compounds are increased. Increasing the travel speed also reduces heat input and recrystallized grain size of the stirred region leading to increased hardness of the joints. The tensile test results showed that the ultimate tensile strength, yield strength, and elongation of the welded samples initially increase by increasing the travel speed and then start to decrease due to the formation of defects in the stir zone. The fracture of all transverse tensile test specimens occurs on the advancing side of the joints. The fracture location of the best specimen is located at the adjacent of the base metal with the heat-affected zone. The maximum mechanical properties are achieved at a travel speed of 40 mm/min, and the welding efficiency in that condition is approximately 97%.

中文翻译：

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行进速度对线轴工具搅拌摩擦焊AA5456-H112厚板显微组织评价和力学特性的影响

摘要 厚度为20 mm 的5456-H112 铝合金板采用浮动线轴工具搅拌摩擦焊，以28 至160 mm/min 的不同行进速度和90 rpm 的固定转速连接。显微组织分析结果表明，在恒定的行进速度（28、40、56、80、112和160 mm/min的速度）下，从后退侧到前进侧，晶粒尺寸减小。而金属间化合物的密度和尺寸增加。提高行进速度还减少了热量输入和搅拌区域的再结晶晶粒尺寸，从而导致接头硬度增加。拉伸试验结果表明，极限抗拉强度、屈服强度、焊接试样的伸长率最初随着行进速度的增加而增加，然后由于搅拌区中缺陷的形成而开始下降。所有横向拉伸试样的断裂都发生在接头的前进侧。最佳试样的断裂位置位于与热影响区相邻的母材处。在移动速度为 40 mm/min 时获得最大的机械性能，并且在该条件下的焊接效率约为 97%。