●Characteristics and scope of application:
It is a kind of high-strength hard aluminum that can be strengthened by heat treatment. It has medium plasticity in annealing, fresh quenching and hot conditions. It has good spot welding properties. It has a tendency to form intergranular cracks when gas welding and argon arc welding. The alloy has a tendency to form intergranular cracks during quenching and argon arc welding. The machinability is good after cold work hardening, but poor in the annealed state. The corrosion resistance is not high, and anodizing and painting methods are often used, or an aluminum layer is added to the surface to improve corrosion resistance.
●Chemical composition:
Aluminum Al: balance
Silicon Si: ≤0.50
Copper Cu: 3.8～4.9
Magnesium Mg: 1.2～1.8
Zinc Zn: ≤0.30
Manganese Mn: 0.30～0.9
Titanium Ti: ≤0.15
Nickel Ni: ≤0.10
Iron Fe: 0.000～0.500
Iron+Ni Fe+Ni: 0.000～ 0.500
Note: Individual: ≤0.05; Total: ≤0.10
●Mechanical properties:
Tensile strength σb (MPa): ≥390
Conditional yield strength σ0.2 (MPa): ≥255
Elongation δ5 (%): ≥12
Note: Longitudinal mechanical properties of rods at room temperature
Sample size: Rod diameter (square rod, hexagonal rod inscribed circle diameter) ≤ 22
●Heat treatment specifications:
1) Homogenization annealing: heating to 480~495℃; holding for 12~14h; furnace cooling. 2) Complete annealing: heating to 390~430℃; holding time 30~120min; furnace cooling to 300℃ and air cooling. 3) Rapid annealing: heating at 350~370℃; holding time at 30~120min; air cooling. 4) Quenching and aging: quenching at 495~505℃, water cooling; artificial aging at 185~195℃, 6~12h, air cooling; natural aging: 96h at room temperature.
