Hot cracking is also known as "solidification cracking," which occurs in weld metals when a molten weld metal freezes, and "liquation cracking," which occurs in the heat-affected zones of the mother metal and weld metal in solid, affected by the heat of the arc. The lack of cohesion between grain boundaries, in turn, initiates cracks aided by tensile stresses resulting from the contraction of the weld. Both these impurities combine with the matrix elements to form low-melting-point (lower than that of the matrix) compounds, thereby reducing intergranular cohesion. The lack of ductility at high temperatures causing the brittle condition near the solidus is usually due to the formation of an intergranular liquid film of an impurity, notably sulfur and phosphorous in metal. It can occur in weld metals and the heat-affected zone.Īlmost all metals (such as carbon steel, low-alloy steel, austenitic stainless steel, nickel alloy, and aluminum alloy) may, on any scale, suffer this defect. Hot crack can be defined as cracking formed at high temperatures near the solidus of the metal, where the metal has coherence but is completely brittle.
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