Step 3 of 4
57%
Nitriding, deeper: why this course exists
The four levers that make one nitriding job different from another, and what a complete nitriding certificate documents that an incomplete one leaves out.
Step 3 of 4Time
Case growth on a nitrided part is roughly parabolic with time. A 60-hour gas cycle on H13 produces a 0.4-0.5 mm diffusion zone; a 15-hour cycle on the same steel produces something closer to 0.2 mm. Time is the single largest contributor to furnace residence and to compound-layer thickness, and it does not scale linearly with case depth — doubling the cycle does not double the case. A short cycle and a long cycle on the same steel produce different cases, not the same case at different speeds.
Quick check
Two gas-nitride quotes on the same H13 part: one specifies a 24-hour cycle, one specifies a 60-hour cycle. The certificate on the 24-hour cycle lists a case depth of 0.4 mm. Should you accept the certificate at face value?