Correct option is D
Weld decay is a phenomenon that occurs predominantly in stainless steel. It is a form of intergranular corrosion that happens when stainless steel is exposed to temperatures between 450°C and 850°C during welding or heat treatment.
The corrosion occurs because chromium carbides form at the grain boundaries, depleting the adjacent areas of chromium, which is essential for the corrosion resistance of stainless steel. This results in a reduced resistance to corrosion in the affected areas, leading to weld decay.
Weld decay can be prevented by using low-carbon stainless steels, stabilizing elements like titanium or niobium, or by performing post-weld heat treatment to dissolve the carbides and restore corrosion resistance.
