crack closure
Crack face contact is the premature closure of crack faces during unloading, which blocks stresses and reduces the crack growth rate.
Physical-Chemical Mechanism of Action
Crack surface contact occurs when the crack faces close too early during the unloading phase of a cyclic loading cycle. This causes part of the external stress amplitude to be shielded, reducing the effective stress at the crack tip.
Metallurgical Relevance & Risks in Welding
High crack surface contact can lead to a reduced crack growth rate, which increases the life of components and structures. However, it can also lead to an uneven stress distribution system, which can cause further crack effects such as microcracks or corrosion.
Workshop Practice & Instructions
To optimize crack surface contact and increase component life, it is important to ensure the material is properly treated. This includes adequate post-weld heat treatment to stabilize the microstructure and balance stresses. Also, when selecting the welding process and materials, consider that high crack surface contact is desired to increase life.