For thin plates (<=6mm) heated to 1000–1100℃, the minimum inner bending radius can be as small as 1.5× the plate thickness (e.g., 9mm radius for a 6mm thick plate).
For thicker plates (>=10mm), the minimum inner radius should be increased to 2.5–3× the plate thickness to prevent grain boundary separation or surface cracking. Consult ASTM standards (e.g., ASTM A6/A6M for general bending guidelines) or the steel manufacturer's recommendations for application-specific radius limits.
: Ensure the entire bending area is heated evenly (using induction heating, gas torches, or furnace heating) to avoid localized overheating or cold spots. Uneven heating can lead to asymmetric deformation or residual stress, which may cause warping after cooling.
: After hot-bending, avoid rapid quenching (e.g., water cooling). Instead, use or slow cooling (<=50℃ per hour) to room temperature. Rapid cooling can induce martensitic transformation in ASTM A588, increasing brittleness and reducing corrosion resistance. For critical applications (e.g., structural components), post-bending stress relief annealing (at 550–650℃ for 1–2 hours, followed by air cooling) is recommended to eliminate residual stresses.
