7A04 is an Al-Zn-Mg-Cu ultra-high-strength aluminum alloy, also known as super-hard aluminum. It is a mature, long-lasting and widely used alloy in super-hard aluminum. High strength, good heat treatment strengthening effect, moderate plasticity under annealing and new quenching conditions; unlike hard aluminum, the corrosion resistance under artificial aging is better than that of natural aging, and the natural aging process is slow, requiring 3 After the month, the age hardening peak can be reached, so 7A04 is used in the quenching artificial aging state. The disadvantage is that the stability of the structure is not high, the low-frequency fatigue strength is low, and there is a tendency of stress corrosion cracking. The alloy spot weld has good weldability, poor gas welding, good machinability after heat treatment, but poor machinability after annealing.
CHEMICAL COMPOSITION
| Alloy grade | Si | Fe | Cu | Mn | Mg | Cr | Zn | Ti | Zr | other | AL | ||
| New Alloy grade | Old Alloy grade | 0.5 | 0.5 | 1.4-2.0 | 0.2-0.6 | 1.8-2.8 | 0.1-0.25 | 5.0-7.0 | 0.1 | -- | every | total | |
| 7A04 | LC4 | 0.05 | -- | ||||||||||
MECHANICAL PROPERTIES
|
Alloy grade and
status
|
tensile strength Rm/Mpa |
Yield Strength Rp0.2/Mpa |
Elongation/% | Hardness/ HBWα |
| 7A04-T6 | 490 | 410 | 7 | 150 |
