Microstructure Evolution during Dissimilar Friction Stir Welding of AA7003-T4 and AA6060-T4

Jialiang Dong; Datong Zhang; Weiwen Zhang; Wen Zhang; Cheng Qiu

doi:10.3390/ma11030342

Microstructure Evolution during Dissimilar Friction Stir Welding of AA7003-T4 and AA6060-T4

Materials (Basel). 2018 Feb 27;11(3):342. doi: 10.3390/ma11030342.

Authors

Jialiang Dong¹, Datong Zhang², Weiwen Zhang³, Wen Zhang⁴, Cheng Qiu⁵

Affiliations

¹ National Engineering Research Center of Near-net shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. 201610100603@mail.scut.edu.cn.
² National Engineering Research Center of Near-net shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. dtzhang@scut.edu.cn.
³ National Engineering Research Center of Near-net shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. mewzhang@scut.edu.cn.
⁴ National Engineering Research Center of Near-net shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. jack_eei@scut.edu.cn.
⁵ National Engineering Research Center of Near-net shape Forming for Metallic Materials, South China University of Technology, Guangzhou 510640, China. cqiu@scut.edu.cn.

Abstract

In this work, the dissimilar joint of AA7003-T4 and 6060-T4 alloy has been produced by friction stir welding (FSW). The microstructure was examined by optical microscope (OM), electron back scattered diffraction (EBSD), transmission electron microscopy (TEM), and the mechanical properties of the joint were investigated. It is demonstrated that sound dissimilar joint can be produced through FSW. In the nugget; precipitations dissolve into the matrix and η' reprecipitate subsequently; and the elongated aluminum grains are replaced by fine and equiaxed grains due to dynamic recrystallization (DRX). In the heat affected zone (HAZ), coarse β' and η precipitates are formed and the aluminum grains are coarser as compared to the base materials. In the thermo-mechanical affected zone (TMAZ), equiaxed and elongated grains coexist due to incomplete DRX. The ultimate tensile strength of the dissimilar joint is 159.2 MPa and its elongation is 10.4%. The weak area exists in the HAZ of 6060 alloy, which is placed in the retreating side during FSW. The correlations between the microstucture and mechanical properties of the dissimilar joint are discussed.

Keywords: dissimilar friction stir welding; dynamic recrystallization; mechanical properties; microstructure evolution.