Due to the characteristics of light weight and high strength

2 A12-T42 aluminum alloy has been used as the main materials of aircraft. Refill friction stir spot welding（RFSSW）as a novel solid phase connection technology

was carried out to investigate the joint

the appearance and microstructure were analyzed by SM and metallographic microscope respectively

the corrosion behaviour of RFSSW joint was investigated by immersion test

static weight loss test and polarization curve test. The experiment results show that the RFSSW joint has a good forming and defect-free on the surface

the metal microstructure and precipitate phase of joint is differentiated in different districts

the grains of SAZ and PAZ are small as the direct stir with the tool

the metal microstructure and precipitate phase of TMAZ is distributed in a certain direction

for the affection of heat input in HAZ

the microstructure grain grew and the precipitate phase coarsed and aggregated. Immersion test shows that the corrosion resistance of 2 A12-T42 RFSSW joint is differentiated in different districts

the corrosion resistance of HAZ is the lowest

and the pitting corrosion is developed firstly

the corrosion resistance of SAZ is the highest. The corrosion resistance of RFSSW joint is lower than that of base metal. The polarization curve test shows that the sequence of the corrosion resistance in each district from high to low was SAZ

PAZ

BM

HAZ/TMAZ.