Stress-Strain Graphs

Below are some annotated graphs which are based on stress strain measurements for a range of materials.

Stress is the force or load applied. Strain is the effect on the material.

 

Annealed copper is the most ductile. Hard drawn brass is the strongest and stiffest. Notice the effect of annealing on copper. Force extension graph comparing metals
  Stress strain graph comparing four metals
This graph of load-extension for mild steel shows very well the behaviour of a strong ductile material. Load extension graph for mild steel