SiCp/2009Al复合材料搅拌摩擦焊T形接头组织与力学性能

Microstructure and mechanical properties of T-type friction stir welded SiCp/2009Al composite matrix material

在工具转速800~1200 r/min、焊接速度100~150 mm/min的工艺参数下,对6 mm厚的硬态(自然时效态)体积分数为15%SiCp/2009Al复合材料轧制板材进行T形搅拌摩擦焊(friction stir welding,FSW),均获得了致密无缺陷的接头.结果表明,FSW过程中,剧烈塑性变形使焊核区部分SiC颗粒发生一定程度的破碎,破碎程度随转速的增加而增加,随焊接速度的增加而减弱;焊核区中的微米级强化相发生破碎、溶解,并沿焊核区细晶界面析出.T形接头横板两侧各存在2个低硬度区,靠近焊核区的低硬度区的硬度比远离焊核区的低硬度区的硬度低;固定焊接速度为100 mm/min时,转速从800 r/min增加到1200 r/min时,接头的抗拉强度不变;固定转速为800 r/min时,将焊接速度从100 mm/min增加到150 mm/min时,接头的抗拉强度轻微降低.接头拉伸过程中在横板与竖板交界处受应力最大,所有接头均在此区域断裂.

6 mm thick 15vol.%SiCp/2009Al matrix composite rolled plates were subjected to T-type friction stir welding(FSW)under the rotation rates of 800-1200 r/min and welding speeds of 100-150 mm/min.The results show that,defectfree joints were obtained and the SiC particles were broken up during FSW;The crushing degree of SiC particles increased with enhancing the welding speed and decreased with the increase of the welding speed.The micron-level precipitates in the nugget zone(NZ)were broken up and dissolved,and then reprecipitated along the fine grain interface of NZ.There are two low hardness zones(LHZ)at both advancing and retreating sides of the horizontal plate of T-type joint,and the hardness of the LHZ close to the NZ is lower than that of the LHZ far away from the NZ.Under the constant welding speed of100 mm/min,the tensile strength of the T-type joint was unchanged when increasing the rotation rate from 800 r/min to1200 r/min.Under the constant rotation rate of 800 r/min,the tensile strength of the joint increased as increasing the welding speed from 100 mm/min to 150 mm/min.The T-type joints fractured at the junction of horizontal and vertical pates during tension test.