Ductility refers to the ability of a material to undergo plastic deformation under tensile stress without fracturing. Forging materials require good ductility to allow them to be formed during forging processes such as hammering, pressing, or rolling without cracking.

Typical ductility properties of common forging materials:

1. Low-carbon steel (forging steel, e.g., 10#, 20#, Q235)

Extremely high ductility. Large plastic deformation can be achieved at room temperature; excellent hot forging ductility. Suitable for complex-shaped forgings. Elongation is typically around 25-40%.

2. Medium-carbon steel (45#, 40Cr)

Good ductility. Ductility is slightly lower compared to low-carbon steel. Primarily used for hot forging. Large deformation processing at room temperature is not recommended. Elongation is approximately 15-25%.

3. High-carbon steel and high-alloy steel

Low ductility. Prone to cracking during deformation. Almost exclusively hot forging is permitted; the forging temperature range is strictly controlled. Elongation is typically below 15%.

4. Aluminum Alloy Forging Billets

Excellent hot ductility. Suitable for complex precision forgings. Some grades exhibit good room temperature ductility.

5. Copper-Based Forging Alloys

High ductility. Can be hot forged, and many grades also support cold forging.

6. Titanium Alloys

Good ductility only within a narrow high-temperature range; poor room temperature ductility. Almost entirely hot forging is used.

Key Factors Affecting the Ductility of Forging Materials

1. Temperature: Hot forging significantly improves ductility; most metals exhibit higher ductility at high temperatures. Cold forging requires the material itself to have high room temperature ductility.

2. Chemical Composition: Higher carbon content and more brittle alloy phases reduce ductility. Impurities such as sulfur can cause hot brittleness, thus compromising forging ductility.

3. Grain structure: Fine, uniform grains improve ductility; coarse grains reduce ductility.

4. Strain rate: Compared to slow pressing forging, rapid hammer forging reduces effective ductility.

Final conclusion:

Good forging materials must possess high ductility at forging temperatures to accommodate large plastic deformations without cracking.