Multistage Quenching Process of Aluminum Alloy Based on Roller-Type Spray Quenching Technology

Based on the experimental results of single-stage quenching test, three kinds of multistage quenching processes were designed. The effect of spraying pressure (p), flux density (q) and duration (t) on the surface residual stress and the microstructure have been investigated. The results show that parameters had little effect on the microstruture. Adopting higher spraying pressure and lower flux density at the first stage of the quenching process can get a greater tempering depth. And increasing the flux density had the better effect on hardening depth than increasing the duration, but the latter had a lower residual stress. The best multistage quenching process was as following: the first stage (p=200 kPa、q=48 L·m-2·s-1,t=3 s), the second stage (p=10 kPa,q=90 L·m-2·s-1, t=12 s), and the third stage (p=200 kPa,q=130 L·m-2·s-1,t=480 s).