J. Mater. Sci. Technol. ›› 2014, Vol. 30 ›› Issue (12): 1243-1250.DOI: 10.1016/j.jmst.2014.04.009

• Orginal Article • Previous Articles     Next Articles

Mechanical Properties and Microstructure of 6082-T6 Aluminum Alloy Joints by Self-support Friction Stir Welding

Long Wan, Yongxian Huang, Weiqiang Guo, Shixiong Lv, Jicai Feng   

  1. State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001, China
  • Received:2013-12-17 Revised:2014-02-23 Online:2014-12-20 Published:2015-07-23
  • Supported by:
    The work was jointly supported by the National Natural Science Foundation of China (Nos. 50904020 and 50974046) and the Fundamental Research Funds for the Central Universities (No. HIT. NSRIF. 2012007).

Abstract: The majority of this research has concentrated on developing the self-support friction stir welding (SSFSW) tool which consists of a big concave upper shoulder and a small convex lower shoulder, and procedures for making reliable welds in aluminum hollow extrusion. The 5-mm-thick 6082-T6 aluminum alloy was self-support friction stir welded at a constant tool rotation speed of 800 r/min. The effect of welding speed on microstructure and mechanical properties was investigated. The results of transverse tensile test indicated that the tensile strength of joints increased and the elongation decreased with increasing welding speed. The whole values of microhardness of SSFSW joints increased with increasing welding speed from 10 to 200 mm/min. The defect-free joints were obtained at lower welding speeds and the tensile fracture was located at the heat-affected zone (HAZ) adjacent to the thermo-mechanically affected zone (TMAZ) on the advancing side. The investigation of the flow pattern of the softened metal around the SSFSW tool revealed that the flow pattern of the softened metal was driven by two shoulders and the stir pin. The failure of specimens in tension presented the ductile fracture mode.

Key words: Self-support friction stir welding, Aluminum alloy, Welding speed, Mechanical properties, Microstructure, Flow pattern