Ductile & Brittle Material

So what is a ductile material and what is a brittle material? Simply a ductile material is a material that will typically deform when a large amount of energy is absorbed into the material during short period of time, while a brittle material will instead shatter when a large amount of energy is absorbed into the material in a short amount of time.

Ductile Material

So what makes a material ductile? A material that is ductile has the ability to deform and essentially absorb quite a bit of energy before it will break. If you were to look at the stress strain plot of a ductile material it would have a very large plastic area that allows quite a bit of strain before the material reaches its fracture stress . There will also be large amount of necking before the material fails.

Brittle Material

Unlike ductile material, a brittle material will have a very small plastic region in comparison. Due to this fact once a brittle material leaves the elastic region it will fail a lot quicker. The break will also be a lot cleaner since there will be less necking.

The images below show what a ductile material break would be in comparison to a brittle material. They also show what the stress strain curves would look like.

Looking at the stress strain curve that is being used to compare a brittle material to a ductile material notice that even though the brittle material can’t absorb as much energy as the ductile material can it typically will have a higher yield point than the ductile material. This means that neither a brittle nor a ductile material is better than the other one. It really depends on what the part is being used for.