Chromium Depletion
Chromium depletion is the local loss of chromium at grain boundaries due to chromium carbide formation during improper heat treatment. This makes austenitic steels susceptible to intergranular corrosion.
Physico-Chemical Mechanism of Action
Chromium depletion occurs when excessive temperatures or uneven cooling in the weld zone remove chromium from the steel. The chromium forms carbides, depleting at the grain boundaries.
Metallurgical Significance & Risks in Welding
Chromium depletion leads to a reduced chromium concentration at the grain boundaries, increasing susceptibility to intergranular corrosion. This can result in cracking and loss of strength in the steel.
Workshop Practice & Action Guidelines
To prevent chromium depletion, ensure even cooling of the weld. Use suitable shielding gas mixtures and protect the steel from improper temperatures during welding.