Microstructure evolution and strengthening mechanisms of high strength Al-Zn-Mg-Cu alloy via pre-hardening forming

作者：Wei, Pengfei; Hu, Zhili^*; Pang, Qiu^*

来源：Journal of Alloys and Compounds, 2023, 968: 172057.

DOI：10.1016/j.jallcom.2023.172057

• Al -Zn -Mg -Cu alloy
• Pre-hardening forming
• GPII zones
• Strengthening mechanism

The precipitating and strengthening behavior of the pre-hardening forming (PHF) process for a high-strength Al -Zn-Mg-Cu alloy is studied. The PHF process obviates the need for artificial aging (120 degrees C for 24 h) during hot forming. Despite the considerably lower volume fraction of eta' (with a maximum of 0.54 %) in the PHF samples compared to that of the T6 samples, the maximum yield strength of the 12 h-5 min tensile specimen is 496 MPa, similar to that of the T6 alloy (490 MPa). It is assumed that the GPII zones have compensated for the insufficient yield strength in PHF samples. Through the integration of small-angle X-ray scattering (SAXS) experiments and the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equations, the strengthening effects attributable to GPII zones and eta' have been discerned. Intriguingly, the contribution of GPII zones to yield strength (219 MPa in the 12 h-5 min sample) equals that of eta' (167 MPa in the 12 h-5 min sample). A comprehensive yield strength model is subsequently established, including both GPII zones and eta' phase, exhibiting a deviation between fitting and experimental results of less than 5 %.

• 单位
  武汉理工大学