静止轴肩搅拌摩擦焊接6005铝合金的力学和疲劳性能

Mechanical and fatigue property of stationary shoulder friction stir welding AA6005

利用静止轴肩搅拌摩擦焊接装置对4.5 mm 6005铝合金进行了研究,为满足工程需求,焊接速度设为1 000 mm/min.结果表明,静轴肩搅拌摩擦焊接头随转速的增加,抗拉强度先升高后降低,当转速为2 100 r/min时最高,为232 MPa,可达母材的80%;各参数接头正弯和背弯180°均无裂纹.在应力循环频率70 Hz、正弦波形、应力比R为0.1的条件下,对2 100 r/min和1 000 mm/min参数的接头进行轴向高周疲劳测试,获得接头的S-N曲线和疲劳极限,在(1-a)置信度90%,失效概率P=5%条件下,S-N曲线的下极限为105 MPa,疲劳断裂主要位于接头的热影响区,疲劳断口分为裂纹萌生区、裂纹扩展区和瞬断区三个区域.

The 4. 5 mm 6005 aluminum alloys was friction stir welded via a stationary shoulder invented by authors. The traveling speed was 1 000 mm/min for industrial production efficiency. The results showed that tensile strength of joint increased firstly and then decreased when rotation speed changed from1 700 r/min to 2 300 r/min. The maximum tensile strength of 232 MPa,account for 80% of parent metal,as rotation speed set as 2 100 r/min. There was no fracture in face bend and root bend sample when bending angle reached 180°. The fatigue strength and S-N curves of samples was investigated at cycle frequency of 70 Hz,R = 0. 1,sine wave. The limit inferior strength was 105 MPa,at condition of( 1-a) confidence coefficient 90%,failure probability P = 5%. The fractography showed that there were three characteristic regions including initiation region,expand region and fracture region in failed fatigue sample.