搅拌针偏心距对焊缝金属塑性流动行为的影响

采用搅拌针偏心距分别为0.1，0.2，0.3，0.4 mm搅拌头对叠层进行焊接试验，分析其对焊缝金属塑性流动行为影响.结果表明，焊缝由轴肩区、紊流区、焊核区及挤压区组成，其中紊流区为焊核区和轴肩区挤压金属形成的结果，前进侧挤压区金属变形尺寸明显大于返回侧.随偏心距增加，焊核区面积、宽度及挤压区标示材料向上迁移高度先增大后减小，前进侧标示材料向上迁移距离大于返回侧.由0.2 mm偏心距搅拌头获得焊核区面积和标示材料向上迁移距离最大.但焊核区宽度最大焊缝由0.3 mm偏心距搅拌头获得.根据焊缝金属塑性流动形态，提出搅拌针波动式挤压物理模型.

Effect of pin eccentricity on flow behavior of plastic material in friction stir welds

Four tools with a pin eccentricity of 0.1, 0.2, 0.3 and 0.4 mm were designed to friction stir weld lamination by inserting tracer material, and effect of pin eccentricity on metal flow behavior of the weld was studied. The results showed that, the cross section of the weld consisted of shoulder zone, turbulent flow zone, nugget zone and extruded zone, and the formation of the turbulent flow zone was contributed to combined extruding action of nugget zone and shoulder zone. Moreover, the size of deformed metals on the AS is larger than on the RS. In the same welding conditions, with increasing pin eccentricity, the area and width of nugget zone increased firstly and then decreased.The changing trend of transfer height of insert tracer materials was similar, and the maximum transfer height on the AS was bigger than on the RS. The area of nugget zone and the transfer height of insert tracer material were produced by a tool pin with an eccentricity of 0.2 mm. But the maximum width of nugget zone was obtained by a tool pin of 0.3 mm eccentricity. According to the three-dimensional plastic flow of the weld metal, a wave extruding physical model of the pin was proposed.