Galvanized steel flat welding occurs after the material itself crack.
Cold crack: a cold crack is a weld crack that occurs when the joint is cooled to a lower temperature. The causes are the quenching tendency, the residual stress, the diffusion hydrogen content of the weld metal and the heat affected zone.
Reheat cracking: when welding in the heat affected zone near the fusion County Office is heated to 1200 DEG C, the heat affected zone of grain boundary of vanadium and molybdenum and titanium carbide in austenite when welding; postweld heat treatment of re heating, the heating temperature in the range of 500 degrees to 700 degrees Celsius in the welding, there is a big the welding residual stress in the joints, stress exceeds the plastic heat affected zone near the fusion line of the metal, will produce crack;
Thermal cracking: most of the material being welded is alloy, and the solidification of the alloy starts from the beginning to the end, which is carried out in a certain range, which is the basic cause of the thermal crack.
