Achieving high-quality metal to polymer-matrix composites joint via top-thermic solid-state lap joining

Abstract

Abstract The joining of metals and polymer-matrix composites (PMCs) is a highly pressing and challenging task in the manufacturing industries. To achieve the reliable hybrid joint, a solid-state joining technique of top-thermic friction stir lap welding (TT-FSLW) was proposed and performed in the joining of 7075 aluminum alloy and SGF/PEEK materials. Through the TT-FSLW with low rotational speed, the excessive overflow of polymer material in conventional FSLW was suppressed, so the satisfactory joint with smooth surface was formed. Thanks to the low heating and cooling rates and the reduced interfacial stress, common FSLW defects of void and crack were eliminated in the TT-FSLW joint. Characterized by the widened effective interfacial joining area and the enhanced interfacial joining with micro and macro mechanical interlockings, the maximum shear strength of joint was enhanced to 59.9\u202fMPa under TT-FSLW, which was increased by 52.4% compared to that under the conventional FSLW. The TT-FSLW technique has been preliminarily proved to be superior to other conventional welding methods in joining metals and PMCs.