Environmental stress fracture

Environments such as moist air, sea water and corrosive liquids and gases cause environmental stress fracture.

Plastics and plastic-based composites may suffer swelling, debonding and loss of strength when exposed to organic fluids and other corrosive environments, such as acids and alkalies.

While their fracture toughness remains unaltered, their threshold stress intensity factor for crack propagation may be considerably lowered.

This process has serious implications on the utilisation of the material because the applicable safe stress levels are drastically reduced in the corrosive medium.

Small quantities of hydrogen present inside certain metallic materials make the latter brittle and susceptible to sub-critical crack growth under stress.