Cold Cracking - Cold cracking also is caused due to metal brittleness combined with a tensile stress exceeding the fracture stress.
Brittleness is the result of
(i) Solidification of the low melting constituents.
(ii) Phase changes (e.g., formation of martensite) during cooling. Martensite formation, when it occurs in steel which is charged with hydrogen, is a potent cause of weld cracking.
Factors promoting cold cracking
1. Joint restraint and high thermal severity.
2. Hydrogen in the weld metal.
3. Presence of impurities,
4. Embrittlement of the heat-affected zone in low alloy steels.
5. Weld of insufficient sectional area.
6. High welding speeds and low current density.Cold cracking occurs in both weld metal and adjacent base metal (HAZ).
