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在不同的搅拌头转速及焊接速度下,对2 mm厚AlCuLi合金进行了搅拌摩擦焊接.结果表明,焊核区由细小等轴再结晶晶粒组成.随搅拌头转速增加,晶粒尺寸逐渐增加;随焊接速度增加,晶粒尺寸略有减小.TEM分析表明,焊核区的析出相大部分溶解,在随后的冷却过程中形成粗大的析出相,而在热影响区析出大量的粗大平衡相.在较低的焊接速度(80 mm/min)下,接头在热影响区的硬度最低点发生断裂,随搅拌头转速增加,接头强度逐渐升高,最高可达母材的87%,延伸率约为10%.而在较高的焊接速度(200 mm/min)下,搅拌头转速较低时,焊核区材料流动不充分,样品在焊核处发生断裂,强度较低,SEM分析表明,断口出现材料流动不充分导致的缺陷;随搅拌头转速增加,断口处缺陷明显减少,对强度影响不显著,接头强度可达母材的84%.
The friction stir welding of 2 mm thick AlCuLi alloy was carried out at different rotating speed of stirrer and welding speed.The results showed that the weld nugget consisted of fine equiaxed recrystallized grains.The grain size increased with the increase of stirring speed The grain size decreases slightly with the increase of welding speed.The TEM analysis shows that the precipitated phase in the weld nugget area is mostly dissolved and coarse precipitates form in the subsequent cooling process and a large amount of coarse balance precipitates in the heat affected zone At lower welding speed (80 mm / min), the joint ruptured at the lowest hardness point in the heat affected zone. With the increase of the rotating speed of the stirring head, the strength of the joint gradually increased up to 87% of the base material, extending Rate is about 10%, while at higher welding speed (200 mm / min), the material flow in the nugget zone is not enough when the rotation speed of the stirrer is low, the sample breaks at the weld nugget and the strength is low. SEM analysis It shows that the fracture has defects caused by insufficient material flow. With the increase of rotation speed of the mixing head, the defect at the fracture is obviously reduced, but the strength is not affected obviously. The joint strength can reach 84% of the base material.