Five-point (1, 2, 3, 4, 5) Stress-Strain diagram for ductile material is shown in figure.

Explanation:

In a typical stress-strain diagram for a ductile material, the points usually represent the following:

• Point 1: Proportional limit or elastic limit. This is the point up to which the material follows Hooke's Law, meaning the stress is directly proportional to strain.
• Point 2: Yield point (often lower yield point). This is the point at which the material begins to deform plastically. Beyond this point, the material will not return to its original shape when the load is removed.
• Point 3: Upper yield point. This is the maximum stress that occurs just before yielding starts. It is usually slightly higher than the lower yield point.
• Point 4: Ultimate stress. This is the maximum stress the material can withstand before necking begins. Beyond this point, the material will start to fail.
• Point 5: Fracture or breaking point. This is the point at which the material ultimately fails and breaks apart.