Grain boundary sensitization

sadia.shahab · Post by **sadia.shahab** » 15 Jul 2010, 09:32

Please explain "Grain Boundary Sensitization" term.

Post by **Nabeel Ahmed Qureshi** » 15 Jul 2010, 12:39

Grain boundary sensitization is normally experienced in Stainless steels at high temperatures(e.g Welding). Normally what happens is that at around 427C chromium combines with carbon within the structure & forms chromium carbide which preciptates out at grain boundries. Chromium carbide being hard makes the structure brittle. The depletion of chromium in the form of chromium carbide leaves the structure makes with low chromium content & makes it prone to corrosion attack.

arcpro · Post by **arcpro** » 15 Jul 2010, 18:22

Nice explanation by Nabeel. Want to add up a few lines.
Sensitization temperature ranges from 450 deg C to 900 deg C and if there is sufficient time in this range, much of chromium combines with carbon to form a stable chromium carbide and eventually reduces the corrosion resistance of stainless steel.
The extent of sensitization depends on the carbon content in the steel and the exposure time. Understandably, if you would be reducing either of both the two, sensitization can be minimized.

sadia.shahab · Post by **sadia.shahab** » 16 Jul 2010, 03:54

thanks

Post by **ashfaqanwer** » 16 Jul 2010, 09:41

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