Brittle Fracture

Brittle fracture is a sudden failure without prior deformation. The crack propagates rapidly, often along grain boundaries, and usually occurs at low temperatures or when the material has become embrittled. When welding, the risk is especially high if you create a hard, brittle microstructure in the heat-affected zone. This often happens with too rapid cooling or when the material is susceptible. A cracked weld under load can then completely fail without warning. In practice, this means you have to control the cooling. For critical materials, this means preheating and controlling the cooling so that the microstructure remains tough. And don't forget that hydrogen in the weld metal can also lead to brittle fractures – dry consumables are a must.