• Tensile stresses yield higher creep strains than compressive stresses in pre-treated Al-Zn-Mg-Cu alloy, with asymmetry becoming more pronounced at higher applied stresses.
• Compressive stress creep aging results in superior mechanical properties compared to tensile stress, despite exhibiting lower creep strain.
• Dislocation density, dislocation moving velocity, and precipitate proportions are the primary microstructural factors governing tension-compression asymmetry.
• Incorporating tension/compression stress asymmetry into creep constitutive models can significantly improve the forming accuracy of creep age forming components for civil aviation.