Chemical composition: 
 Iron (Fe) 0.7 Manganese (Mn) 0.40 ~ 1.0 magnesium (Mg) 0.4 ~ 0.8 Silicon (Si) 0.2 ~ 0.8 Zinc (Zn) 0.25 Titanium (Ti) 0.15 Chromium (Cr) 0.1 Copper (Cu) 3.5 ~ 4.5 aluminum ( Al) margin Fe + Ni Fe + Ni: 0.000 ~ 0.700 Note: Individual: ≤ 0.05; Total: ≤ 0.10 
 Mechanical Properties: 
 Tensile strength σb (MPa): ≥ 370 conditions the yield strength σ0.2 (MPa): ≥ 215 Elongation δ5 (%): ≥ 12 Note: The vertical bars at room temperature mechanical properties of the sample size: bar diameter (side bar , hexagonal rods inscribed circle diameter) ≤ 150 
 Heat Treatment Specification: 
 1) homogenization: Heat 480 ~ 495 ℃; insulation 12 ~ 14h; furnace cooling. 2) complete annealing: heating 390 ~ 430 ℃; holding time of 30 ~ 120min; air cooling. 3) rapid thermal annealing: heating 350 ~ 370 ℃; holding time is 30 ~ 120min; air cooling. 4) quenching and aging: hardening 495 ~ 510 ℃, water; artificial aging 155 ~ 165 ℃, 6 ~ 10h, air-cooled; natural aging: 96h at room temperature