An Experimental Investigation of the Microstructures, Mechanical, and Corrosion Properties for 7B04 Aluminum Alloy Stiffened Components after Creep Age Forming with Different Process Parameters
摘要
The effects and corresponding mechanisms of key process parameters in creep age forming (CAF), such as temperature, time, and die radius, on the springback, mechanical, and corrosion properties, of 7B04 aluminum alloy stiffened components have been experimentally examined and analyzed through a set of orthogonal experimental designing of mechanical and microstructural tests. The results indicate that temperature plays the most dominant role in springback, while forming time and die radius also contribute important roles. An increase in CAF temperature and time causes the phase transition of the η′ phase into the η phase, accompanied by coarsening and discontinuity, where the bypass mechanism is dominant. This transformation subsequently reduces the strength of the alloy, while the springback experiences a significant decrease. However, the corrosion resistance of the alloy is improved. The process parameters of CAF have been optimized (160°C + 20 h), with the high requirement of mechanical properties, corrosion resistance, and springback after forming (σb ≥ 530 MPa, σ0.2 ≥ 420 MPa, δ ≥ 7.0%), and exhibits superficial exfoliation corrosion, while also achieving higher forming efficiency. (The springback rate decreases to 56.5%.) The above results provide a technical basis and experimental data for the engineering application of CAF for 7B04 aluminum alloy stiffened parts.