Centerline hot crack
A centerline hot crack is a separation crack in the weld that occurs during solidification. It is promoted by stresses and low-melting grain boundary films.
Physical-Chemical Mechanism of Action
A centerline hot crack forms when the weld separates along the weld axis during solidification under high stress and strain. This often occurs in areas with low-melting grain boundary films that cannot compensate for the stresses.
Metallurgical Relevance & Risks in Welding
A centerline hot crack can lead to severe mechanical loading and impair the strength of the weld. It can also cause further cracks and deformations in the component, endangering the entire structure.
Workshop Practice & Instructions
To avoid centerline hot cracks, careful weld preparation is important. This includes proper cleaning and removal of grain boundary films. Additionally, welding speed and temperature should be controlled to avoid uneven stresses. For heavy materials or high loads, additional post-treatment such as austenitizing or tempering may be required.