It is a commonly used super-hard aluminum, which is a high-strength alloy and can be heat-treated. It is usually used in the quenching artificial aging state. At this time, the strength is much higher than that of the general hard aluminum, but the plasticity is low; the extruded semi-finished product and the aluminum-clad plate which are not too thick in cross section have good corrosion resistance and tend to stress concentration. The spot weldability is good, the gas welding is poor, and the machinability is good after heat treatment and low in the annealed state.
It is an ultra-high-strength aluminum alloy of Al-Zn-Mg-Cu type, also known as super-hard aluminum. It is an alloy that is expected to be mature and used 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 tissue stability is not high and the low frequency fatigue strength is low.
7A04 aluminum wire chemical composition
Silicon Si≤:0.50
Iron Fe≤: 0.50
Copper Cu: 1.4-2.0
Manganese Mn: 0.20-0.6
Magnesium Mg: 1.8-2.8
Chromium Cr: 0.10-0.25
Zinc Zn: 5.0-7.0
Titanium Ti≤:0.10
Aluminum Al: balance
Other: Single: 0.05 Total: 0.10
7A04 aluminum wire mechanical properties:
Tensile strength &;b (MPa): ≥ 530
Conditional yield strength &;0.2 (MPa): ≥400
Elongation δ10 (%): ≥5
Note: Longitudinal mechanical properties of pipe at room temperature Specimen size: all thicknesses
7A04 aluminum wire heat treatment specification:
1) Homogenization annealing: heating 450 ~ 465 ° C; holding 12 ~ 14h; furnace cooling.
2) Complete annealing: heating 390 ~ 430 ° C; holding 30 ~ 120min; furnace cooling to 150 ° C air cooling.
3) quenching and aging: quenching 465 ~ 480 ° C, water-cooled; artificial aging (including aluminum sheet) 115 ~ 125 ° C 24h, (not included aluminum profiles) 135 ~ 145 ° C 16h, (semi-product) 1 level 115 ~ 125 ° C 3h heating, 2 levels 155 ~ 165 ° C 3h air cooling.
