厚铝合金板搅拌摩擦焊塑性金属不同深度的水平流动状况

Horizontal flow status of plastic metal in different depth during friction stir welding for thick aluminum alloy

通过在 10mm厚LF2铝合金板的不同位置嵌入示踪Fe粉, 进行搅拌摩擦焊对接实验, 焊后截取不同深度的水平面试样, 采用扫描电镜对试样进行能谱分析, 通过观察Fe粉在焊缝金属中的水平分布, 确定了 10mm厚LF2搅拌摩擦焊焊缝金属的二维水平流动状况。结果表明, 塑性金属流动关于焊缝中心并不对称。焊缝下部金属受搅拌针作用, 前进侧大部分金属与焊接方向相反向后流动, 小部分金属向前流动, 但都未进入返回侧; 返回侧金属都向后流动, 且有部分金属进入前进侧。焊缝上部金属主要受轴肩作用, 前进侧大部分金属向前流动但未进入返回侧, 小部分金属向后流动; 返回侧金属沿旋转方向流入前进侧。

Marker Fe grains were inserted into 10mm LF2 aluminum alloy in different positions during the friction stir welding course. After butt welding, the samples which were selected in horizontal sections in different depths were analyzed by using EDS(energy dispersive X-ray spectroscopy) of SEM(scanning electron microscope). The 2-D horizontal flow status of friction stir welding for 10mm LF2 aluminum alloy was confirmed by observing the horizontal distributions of Fe grains in welding zone. The results show that the flow is not symmetric about the weld centerline. The lower metal of weld is completely affected by pin. The bulk of metal in the advancing side is transported backward against the welding direction. However, a small amount is moved forward at the edge of the pin. The metal in the retreating side is only transported against the welding direction and some metal flows into the advancing side. The upper metal of weld is mainly affected by shoulder. The bulk of metal in the advancing side moves forward in the welding direction and a little backward; but no metal flows into the retreating side. However, the bulk of metal in the retreating side is transported backward into the advancing side along the rotation direction.