INDIAN INSTITUTE OF TECHNOLOGY

INDIAN INSTITUTE OF TECHNOLOGY KANPUR

Department of Materials and Metallurgical Engineering

Virtual Laboratories for Thermal Processing and Characterization of Materials

Mechanical Testing Laboratory

Tensile Properties from the stress-strain curve

The slope of the initial straight line segment of the stress-strain curves gives the Young's Modulus.
For most materials there is no sharp transition from the elastic region to the plastic region. Hence, a small strain, such as, 0.1% or 0.2% strain is chosen to determine the yield stress. Such a stress is termed as 0.1% or 0.2% offset yield strength. The methodology for determining the proof strength is shown in the figures above.
The peak in the engineering stress-strain curve is the ultimate tensile stress or the tensile strength of the mateial.
The stress at which the material fractures is the fracture strength.
The total strain after fracture (can be calculated by measuring the final length by joining the two broken pieces) is as shown in the figure on the right above.