Local changes in the microstructure, mechanical and electrochemical properties of friction stir welded joints from aluminium of varying grain size

Journal article (2021)

Authors

Marta Lipińska Military University of Technology
Florian Pixner Graz University of Technology
Andreas Hütter Graz University of Technology
A.M. Kooijman Team Arjan Mol - Mechanical, Maritime and Materials Engineering
Cezary Jasiński Warsaw University of Technology
Y. Gonzalez Garcia Team Yaiza Gonzalez Garcia - Mechanical, Maritime and Materials Engineering
Norbert Enzinger Graz University of Technology
Małgorzata Lewandowska Warsaw University of Technology
Research Group
Team Arjan Mol (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2021 Marta Orłowska, Florian Pixner, Andreas Hütter, A.M. Kooijman, Cezary Jasiński, Y. Gonzalez Garcia, Norbert Enzinger, Małgorzata Lewandowska
DOI: https://doi.org/10.1016/j.jmrt.2021.11.057
More Info
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Published Date

2021

Language

English

Faculty

Mechanical, Maritime and Materials Engineering

Department

Materials Science and Engineering

Research Group

Team Arjan Mol

Abstract

The present study shows results of friction stir welded (FSW) samples after different plastic deformation routes. The welds were made of coarse-grained and ultrafine-grained commercially pure aluminium. As a plastic deformation method a new hybrid process has been chosen, which resulted in obtaining samples with different characteristics of microstructure, which also differed in dependance of the examined plane. Microstructure observations showed that, regardless of the base material, due to continuous dynamic recrystallization a stir zone was characterized by equiaxial grains with an average size of 3.5–5.0 μm. However, significant differences in the changes of the microstructure in thermomechanically affected and heat affected zones have been obtained between welds. Microhardness profiles revealed a decrease in the stir zones in comparison with the initially deformed samples, but an increase for the annealed samples. Tensile tests showed differences between the samples. In the deformed samples, the rupture occurred in a stir zone, while in the undeformed samples in the base material. In addition, due to the application of 3D digital image correlation, it was possible to observe deformation and local changes between the weld zones during the tensile test. Additionally, local electrochemical measurements were performed with two sizes of working electrode, which included the application of microcapillary technique. The results showed higher corrosion resistance in 3.5% NaCl in the stir zones.