Mechanical properties evolution during post-welding-heat treatments of double-lap Friction Stir Welded joints

作者：Cerri E^*; Leo P

来源：Materials & Design, 2011, 32(6): 3465-3475.

DOI：10.1016/j.matdes.2011.01.052

• Mechanical properties
• Non-ferrous metals and alloys
• Heat treatments

The present study focuses on double-lap Friction Stir Welded (FSW) joints in 2024T3 and 7075T6 aluminium alloys subjected to several post-welding-heat treatments at warm (typical aging) and high temperature (solution range) followed by room temperature deformation (tensile tests). The effect of post-welding-heat treatments on the microstructure and mechanical properties of double lap FSW joints were investigated. Polarized Optical Microscopy (POM) and Scanning Electron Microscopy (SEM) analysis reveal a progressive change in grain size and morphology in high temperature post-welding-heat treated joints, leading to Abnormal Grain Growth in the stir zone. Stress-strain curves are rather flat for 200 degrees and 300 degrees C post-welded heat treated joints while, for the other set of samples, stress increases with strain to reach maximum stress of 140-160 MPa. Micro-hardness profiles measured on transversal sections of post-welded heat treated joints reveal conditions (temperature and time) of hardness homogeneity at top, bottom and central nugget zone and/or along the whole measured profile. When homogeneity is reached, fracture occurs in the nugget. A relationship between hardness and tensile properties has been applied in the nugget.

• 出版日期2011-6