ASTM A131 B steel plate shall be welded in strict accordance with the process specification, and the welding line energy is generally controlled below 5000J/cm. If the line energy is too large and the weld metal stays at high temperature for a long time, the heat affected zone will be overheated and the grain size will be enlarged, and the plasticity of ASTM A131 B steel plate will become worse and the crack resistance of the joint will be reduced.
However, if the line energy is too small, the cooling speed of the joint will be accelerated, the cooling time will be shortened, and the heat affected zone of ASTM A131 B steel plate will be hardened, which is not conducive to the escape of hydrogen, so it also increases the tendency of cold cracking. Therefore, the energy of welding line should be strictly controlled during construction.
The welding environment of ASTM A131 B steel plate should be stable to avoid the influence of air flow on the protective effect of gas. Avoid welding ASTM A131 B steel plates in wet conditions. Because it is a multi-pass welding, the spatter between layers should be cleaned thoroughly. Clean the root thoroughly with air gouging before welding on the back, grind the groove, clean up and weld.
