During some carburizing operations, carbides might form. If the carbide formation is considered to be finely disbursed carbides, they are generally not seen as problematic. Very coarse and large carbides that can occur at or very close to grain boundaries, however, could be considered to be detrimental.

Carbides can be formed as a result of excessive surface-carbon content that has the potential to occur during carburizing if the carbon potential of the furnace atmosphere is not accurately controlled.

Carbides can also form as a result of carbon reaction with the following alloying elements: chromium, molybdenum, vanadium and titanium.

The carbides can exist in the following form: intergranular carbides, massive carbides, film carbides and globular carbides.

The uncontrolled formation of carbides can influence the following mechanical properties: hardness, residual stress, bending fatigue, contact fatigue and toughness.

Next time, we will discuss the things to consider when designing an optimized carburizing operation.