Cryogenic forging effects and mechanisms on surface coarse grain microstructure in H-shaped 7050 aluminum forgings

Abstract

This study investigates the differences in microstructural control between cryogenic forging combined with pre-deformation (PCF) and traditional thermal forging (TTF) for 7050 aluminum forgings intended for aerospace applications. The PCF process, utilizing cryogenic deformation, significantly refines the coarse grains at the surface of the forgings, resulting in a finer and more uniform microstructure, thereby effectively addressing the issue of surface coarse grains associated with traditional methods. The findings indicate that the PCF process can accumulate higher stored energy, facilitating static recrystallization (SRX) during subsequent heat treatment and enhancing the microstructural uniformity. Utilizing various analytical techniques, including optical microscopy (OM), electron backscatter diffraction (EBSD), and transmission electron microscopy (TEM). This study reveals the superiority of the PCF process in terms of strain accumulation, dislocation density, and grain refinement. In conclusion, this method offers advantages in enhancing the performance and microstructural uniformity of 7050 aluminum forgings, presenting new opportunities for applications in the aluminum forging industry.

Keywords

7050 aluminum alloy / cryogenic forging / coarse grains / dislocation density / stored energy

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Central South University