How does thickness affect the price per ton of I-beams?

Thicker I-beams (flange/web >10mm) cost 15-20% more per ton than thinner ones. For example, a 12-inch I-beam with 5mm flanges may cost $700/ton, while an identical shape with 10mm flanges is $820/ton. Thicker sections require more raw material and slower rolling speeds, increasing production time. They also undergo additional testing (ultrasonic inspection) to ensure internal quality, adding costs. However, thicker I-beams offer higher load capacity, making them cost-effective for long spans (e.g., 20m bridges) where fewer supports reduce overall project costs.