Question

What is a ductile-to-brittle transition? What three factors can cause a metal to experience a ductile-to-brittle transition?

Answer 1

At low temperature some metals that would be ductile at room temperature become brittle.

This temperature is known as transition temperature it is the maxium temperature in which a given material has the ability to absorbe a specific amount of energy without fracturing.

One that factor is temperatue which cause transition.

Second one is strain - in bcc metals such as low carbon steel which becomes brittle at low temperature or at very high strain.

Generally FCC metals remain ductile at low temperature.

In metals deformations at room temperature occur by dislocation motion.

Stress required to move the dislocation is too high that metal will fall instead by propagation of cracks which is third factor.

In FCC flow stress is not temperature dependent so dislocation movement remain high even at low temperature and ductile .