Relationship between stress corrosion resistance and microstructure of rapidly solidified Al-Zn-Mg alloys

Abstract

The stress corrosion cracking SCC resistance of hot-extruded P/M Al-Zn-Mg alloys, Mesoalite, was investigated as compared with that of I/M Al-Zn-Mg alloys and the correlation between stress corrosion resistance and microstracture was studied. SCC resistance about P/M alloys was high as compared with that of I/M alloys and when the solute concentration increased, reduction of SCC resistance about P/M alloys was not observed. The difference in width of PFZ, distribution of precipitates on grain boundary, the amount of metastable phase precipitated in the matrix, tilt angle of grain boundary, grain size and shape was investigated as a cause of the difference of SCC resistance. The large change in the size and shape of grain among these factors was observed. In the P/M alloys, the fiber-like grain elongated to the extruded direction was observed to the equi-axial grain having been observed in the I/M alloys. When stress was applied parallel to elongated grains, the stress perpendicular to the grain boundary was low. Since the SCC resistance is improved when the applied stress perpendicular to the grain boundary is small, it is concluded that the SCC resistance of the P/M alloys which has the fiber-like grain elongated to the ED became large.

Stress-Corrosion Cracking Property of Aluminum-Magnesium Alloy Processed by Equal-Channel Angular Pressing

“…However, in solutions containing Cl − , pitting corrosion occurs locally where the oxide film is attacked by Cl − [1,2]. When additional stress is applied, stress-corrosion cracking also occurs along the crystal grain boundary, resulting in serious damage [3][4][5]. On the other hand, reducing the grain size of metallic materials to the submicrometer or even the nanometer range by equal-channel angular pressing (ECAP), high-pressure torsion (HPT), or a severe torsion-straining process (STSP) is being studied increasingly with the aim of improving mechanical properties such as strength and ductility [6][7][8][9][10][11].…”

Formation of Nano-Microstructured Aluminum Alloy Film Using Thermal Spray Gun with Ultra Rapid Cooling

“…For example, the microstructure of aluminum containing titanium solidi ed using a single roller was examined [5][6][7] . Furthermore, new high speci c strength aluminum alloys for use in lighter, more functional automobile components have been developed by optimization of the chemical composition and the rapid solidi cation technique [8][9][10] . Ultra ne grained aluminum alloy produced by severe plastic deformation shows high corrosion resistance 11) .…”