对4组6061 -T6铝合金搅拌摩擦焊接头进行焊后人工时效处理,采用OM,SEM等分析了时效处理工艺对接头的组织和力学性能的影响规律和机制.研究表明:焊缝截面形貌呈现典型的3个区,时效处理后,焊缝区晶粒形貌无显著变化,晶界较自然时效清晰,晶内析出相也明显增多；接头强度和显微硬度随人工时效处理时间的延长而提高,提高幅度随保温时间逐渐减小；时效处理为8h时接头力学性能优良,接头抗拉强度均达到265 MPa以上,约为母材的93.0％；焊核区硬度达到90 HV,约为母材的90％.时效处理中,焊接过程中固溶在基体中的第二相粒子析出,形成弥散强化效应,大幅提高接头的强度和硬度.随着时效时间的延长,析出粒子逐渐较少,强化效应逐渐减弱；接头最薄弱的区均位于后退侧的热机械影响区,其最低硬度值约为母材的75％.拉伸断口均与拉伸方向成约45°角,断口平整,呈典型的切断断口形貌,与自然时效接头的断口形貌相比,时效处理后接头的断口韧窝大而浅,塑性稍有降低.
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