Bending steel risks damaging it. The further you bend a piece of steel, the greater the chance it will fracture, creating cracks and permanently reducing the material's life. Engineers describe the sharpness of a steel's curve in terms of the curve's radius, with a smaller radius signifying a higher curvature. The steel's bend radius is the smallest possible curve radius the steel can experience without cracking. This value depends of the steel sheet's thickness and the change in its cross-sectional area during a fracture.
Divide 50 by the steel's percentage tensile reduction in area, which is the change in its cross-sectional area during a fracture. The manufacturer provides this value, which varies between grades of steel. If, for instance, your steel has a percentage tensile reduction of 10 per cent: 50/10 = 5.
Subtract 1 from this answer: 5 - 1 = 4.
Multiply this answer by the steel's thickness. If, for instance, the steel is 0.5 inches thick: 4 * 0.5 = 2. The steel's lowest possible bend radius is 2 inches.