Basic Knowledge of Aluminum Forgings

1. When considering the forging temperature of aluminum forgings, the temperature drop during the contact between the blank and the tool and die shall be considered, and the tool and die shall be preheated.

2. For the alloy with high degree of difficult deformation, slow deformation shall be adopted as far as possible, and the deformation amount of each stroke of each hammer or press shall be controlled at about 20% generally. For the material sensitive to speed, the temperature effect shall be considered when selecting the deformation speed.

3. The plasticity of closed die forging is better than that of open die forging, while that of open die forging is better than that of free forging. In the process of free forging, the elongation of the die anvil and the upsetting with a ring can give more play to the plasticity of the metal than the elongation of the flat anvil and the upsetting without a ring.

4. In case of low plastic elongation, attention shall be paid to the selection of appropriate feed ratio. If the feed ratio is too small, the deformation is concentrated at the upper and lower parts, and the center is not forged through, and tensile stress is generated along the axial direction, leading to internal transverse cracks. During upsetting, soft cushion upsetting or overlapping upsetting (used for forging thin cake shaped parts) is often used to improve the non-uniformity of deformation and prevent surface cracks.

5. When considering the forging process, especially the forging of the last heat, it should be avoided to carry out at the critical deformation degree as far as possible to avoid getting coarse grain structure. Specifically, the metal has good plasticity and small deformation resistance under high temperature, so the forging with large deformation far greater than the critical deformation degree should be adopted; During low temperature correction, small deformation lower than the critical deformation degree shall be used for local correction.