Reducing welding hot cracking of high-strength novel Al–Mg–Zn–Cu alloys based on the prediction of the T-shaped device

Abstract

The higher hot cracking tendency during fusion welding in traditional high-strength 7000 series alloys has been an obstacle for its further application. In this study, the cracking susceptibility can be suppressed by fabricating Al-Mg-Zn-Cu alloys with Zn/Mg ≤ 1 and Cu/Mg ≤ 0.25 while simultaneously maintaining the high strength. A T-shaped device combined with nonequilibrium solidification is developed to simulate the solidification during fusion welding, and it is effective to predict the shrinkage load, temperature and solid fraction. The effect of solidification temperature range, the amount of eutectics at the terminal stage of solidification and the shrinkage load during solidification on the hot cracking susceptibility are discussed in detail.

Effect of Final Thermomechanical Treatment on the Mechanical Properties and Microstructure of T Phase Hardened Al-5.8Mg-4.5Zn-0.5Cu Alloy

“…Based on the previous experiment results [21,33] and the DSC analysis, 480 • C was selected as the solution treatment temperature with a holding time of 30min. The parameters for the pre-aging and final aging stages were set as 90 • C/24 h + 140 • C/25 h and 90 • C/48 h + 140 • C/13 h, respectively, with reference to optimized conditions in early studies [21,36], denote as T6-a and T6-b. as listed in Table 2 with the detailed process information.…”

“…The main difference lies in the stage sequence of pre-deformation during the entire process. For the first type, the pre-deformation is performed after the pre-aging stage [18,39], which was adopted in the earlier studies of our group [10,22,36]. The advantage of this arrangement is that artificial aging can be initiated quickly after the solid solution treatment, thus the potential negative effect of natural aging [21] during the stage intervals of the process can be mitigated.…”

Recent advances in hot tearing during casting of aluminium alloys

“…Importantly, this device provides information on the hot tearing susceptibility and load developments, and it has been applied to different AA7xxx alloys [26,[76][77][78]. Recently, Pan et al [79] replaced the T-shaped graphite mould with a bronze mould to obtain higher cooling rates ranging from 11 to 24 K/s to further simulate the solidification during fusion welding. Compared with the CHT rig, this T-shaped device does not contain a feeder to provide good liquid feeding to the critical region during solidification, and this aspect Fig.…”

Microstructure and mechanical properties of TiC nanoparticles reinforced 7075 aluminium alloy fabricated by oscillating laser-arc hybrid additive manufacturing

“…Aluminium alloys are important structural materials in aerospace and other industries owing to their desirable properties of low density, high specific strength and superior corrosion resistance [1,2]. As a typical ultra-high-strength aluminium alloy, the 7075 (Al-Zn-Mg-Cu series) aluminium alloy is widely utilised in modern constructions of aircraft, spacecraft and satellites [3]. Large-scale aluminium alloy components made of 7075 aluminium alloy, such as fuselages and wing ribs, are still routinely manufactured by casting, forging, and welding processes [4], which result in the long manufacturing cycle, low material utilisation efficiency and high cost [5].…”