How To Calculate Ductility

Ductility is a mechanical property of materials that refers to the degree of plastic deformation a material can sustain prior to fracture. If little or no plastic deformation can occur, the material is brittle. You can express ductility in terms of either a percent elongation or a percent reduction in an area. However, the values for percent elongation and percent reduction in area are not necessarily the same for the same material.

1. Measure Gauge Length

Measure the original gauge length (Lo) of the material around the point of intended fracture. This value is commonly 2 inches or 50 millimeters.

2. Apply Tensile Force

Apply a tensile force to the material slowly until fracture occurs.

3. Measure Fracture Length

Fit the broken parts back together and measure the fracture length (Lf), using the same endpoints on the material as the initially measured gauge length.

4. Work out Elongation

Calculate the percent elongation using the equation 100 x (Lf-Lo) ÷ Lo.

1. Measure Diameter

Measure the diameter of the solid cylindrical material to be tested (d).

2. Find Area

Calculate the original cross-sectional area (Ao) of the rod by inserting the diameter into the equation pi x (d ÷ 2)^2.

3. Apply Tensile Force

Apply a tensile force to the material slowly until fracture occurs.

4. Find Area at Point of Fracture

Measure the diameter of the cylinder at the point of fracture (df) then calculate the cross-sectional area at the point of fracture (Af), using the same equation.

5. Apply Equation

Calculate the percent reduction in area using the equation 100 x (Ao-Af) ÷ Ao.