Cold cracks - local intercrystalline fracture of weld metal occurring under the influence of intrinsic welding stresses.
The formal signs of cold cracks that distinguish them from hot cracks are the fact that cracks are detected by visual observation, as a rule, after the welded joint is completely cooled and a brilliant break without traces of high-temperature oxidation.
Cold Crack Propensity Assessment
The main parameters for assessing the tendency of steels to form cold cracks are the carbon equivalent (C equiv ) and the crack formation parameter P cm
To determine the value of the carbon equivalent in world practice, several different parametric equations are used, the most complete of them
C eq =
- at С equiv > 0.45 - steel is prone to the formation of cold cracks
- at С equiv <0.25 - steel is not prone to the formation of cold cracks
However, for modern ferritic-bainitic and bainitic steels, the formation of cold cracks does not occur at С equiv > 0.45
The parameter P cm is determined by the Ito-Bessio parametric equation
P cm =
- Hot crack
Nikolaev G. A. Welding in mechanical engineering: a Handbook in 4 volumes. - M.: Mechanical Engineering, 1978 (1-4 tons).