Proportional Limit On Stress Strain Curve. Proportional limit proportional limit is point on the curve up to which the value of stress and strain remains proportional. All the metals behave like an elastic material up to a specific range.
A tensile test is done on the material for drawing the stress strain curve. That means stress is directly proportional to strain. Hooke’s law states that the strain of the material is proportional to the applied stress within the elastic limit of that material.