Intergranular corrosion in the weld zone—intergranular corrosion at different locations on the joint—“Cr-depletion” prevents intergranular corrosion in the weld zone. Measures to be taken include: 1 After welding data, the weld metal may become ultra-low carbon, or Containing sufficient stabilization elements Nb, it is generally desirable that Nb ≥ 8% or Nb ≈ 1%; 2 adjust the weld composition to obtain the necessary ferrite (δ) phase.
The role of δ phase in the weld: First, it can disrupt the purpose of the target of a single γ-phase columnar crystal, and does not constitute a continuation of the chromium-depleted layer; Second, it is rich in the δ phase and has a good condition for Cr, which can increase the γ grain composition. Chromium-depleted layer.
It is often expected that there is 4% to 12% of the δ phase in the weld.
(2) HAZ sensitization zone intergranular corrosion 1HAZ sensitization zone intergranular corrosion, which refers to the intergranular corrosion that occurs in the heat-affected zone of the welding heat affected zone at the sensitized heating zone.