Nitrided h-11 tool steel with Nitride networks 1

dadoldie (Visitor) Jan 30, 2002
per the ams 2759/6 para 3.7 & 3.7.1

we have a job that the parent material is ams 6487 (h-11 tool steel) that requires core hardness of Rc 38-46
case depth of .011-.020 per ams 2759/6...
case hardness of R15n 92 min

these are ext splines by the way.....

#1) what causes nitride networks during nitride..

#2) when is difinable as a nitride network

#3) is it reworkable to remove the nitride network..

 

[Nitron]

You are probably referring to the network of carbo-nitrides
that precipitate in the diffusion zone at the former austenite grain boundaries.

Since these carbonitrides are brittle, the mechanical properties of grain boundaries with these precipitates differ from those of the grain boundaries without these precipitates. When subjected to critical stresses, these differences can result in micro-cracks, that in turn can initiate fatigue failure.

Carbonitride precipitates of this kind are typical in gas and salt bath nitrided and quench hardened steels. These predipitates can be avoided in ion nitriding, thus eliminating a major cause of the brittleness. This is achieved through a controlled decarburizing during the nitriding process.

Once formed, these precipitates can only be removed by grinding off the material affected.

Pramod Kotwal
Nitron, Inc.
pramodkotwal@nitron.nu