Originally Posted by
NoScoE30
This is quoting H&M Metal Processing. I am waiting on the heat treat spec for the trunnion.
"Q: What is the effect on the core hardness?
A: If the core region's depth is not influenced by diffused nitrogen, the degree of tempering associated with time and temperature during the Black Nitriding cycle determines change in core hardness as follows:
1. Additional tempering occurs during Black Nitriding if the pre-hardened component has been pre-tempered below the subsequent Black Nitriding temperature. Reduction in core hardness depends primarily on the steel grade used and attendant-tempering characteristics.
2. If the pre-hardened component is pre-tempered, or non-pre-hardened above subsequent temperature, core hardness will not change significantly as a result of the Black Nitriding process."