Effect of new RRA aging regression treatment optimization on microstructure and properties of Al-Zn-Mg-Cu alloy

After the regression stage, 24 h natural aging was added to design a new multi-stage aging process. This paper studies the mechanical properties and corrosion resistance of Al-Zn-Mg-Cu alloy treated by different regression aging treatment systems using a tensile test and electrochemical corrosion test using an Al-Zn-Mg-Cu alloy extrusion tube for oil drilling rods. After different aging heat treatments, the alloy’s microstructure was observed by scanning electron microscope and transmission electron microscope, and the related mechanism was explored and analyzed. When optimizing the new multi-stage aging system, it is found that increasing the regression temperature or prolonging the regression time can decrease the tensile strength and improve the corrosion resistance of the alloy. After optimization, the optimal parameters of the RRA aging process are determined as 100 ℃/24 h+168 ℃/4 h+ water quenching +NA/24 h+80 ℃/34 h. After the aging treatment, the alloy has the best comprehensive properties. After the aging treatment, the tensile strength of the alloy is 672 MPa, the yield strength is 628 MPa, the elongation is 10.5%, and the self-etching current density is 6.29 μA/cm².