Temperature Range: The steel needs to be heated to a temperature of up to 1100 °C. Generally, the recommended hot - bending temperature range is between 900 °C and 1100 °C. When the temperature is lower than 900 °C, the material has a higher yield strength, requiring greater force for bending and increasing the risk of surface defects. When the temperature is higher than 1100 °C, excessive grain growth may occur, which will reduce the mechanical strength and weather resistance of the steel.
Bending Radius: For thin plates (≤6mm) heated to 1000 - 1100 °C, the minimum inner bending radius can be as small as 1.5 times the plate thickness. For thicker plates (≥10mm), the minimum inner radius should be increased to 2.5 - 3 times the plate thickness to prevent grain boundary separation or surface cracking.
Pre - heating Temperature: For larger plate thicknesses and bending radii, appropriate pre - heating temperatures and times should be determined according to specific conditions and relevant standards. Although the specific pre - heating temperature is not clearly specified in the publicly available information, for thick plates of high - strength low - alloy steels in general, pre - heating to 300 - 500 °C before reaching the full hot - bending temperature is beneficial to minimize thermal stress and uneven deformation.
Cooling Method: After hot - bending, rapid quenching (such as water cooling) should be avoided. Air cooling or slow cooling (≤50 °C per hour) to room temperature is recommended. For critical applications, post - bending stress relief annealing at 550 - 650 °C for 1 - 2 hours, followed by air cooling, can be carried out to eliminate residual stresses.
