CN · Carbonitriding
Carbon and nitrogen diffused together into the surface, then quenched and tempered. A shallower case than carburising, with good wear resistance on plain and low-alloy steels.
- Furnace
- SQF-1, 2, 3 → TFC
Source · STEP process inspection records
What it does
A thin, wear-resistant case on small parts.
Nitrogen improves hardenability of the case, so plain carbon steels harden well in oil with less distortion. It suits small, thin parts that need wear resistance more than deep case.
- Specify it for small parts that need a wear-resistant case more than a deep one.
- Tell us surface hardness, case depth and its limit hardness, and core hardness if it matters.
- Choose carburising instead when the drawing needs a deeper case or the load is heavy.
Typical cycle
The cycle, as we run it.
- Boost870 °C · NH₃ added
- Quenchoil 110 ± 10 °C
- As quenched89–93 HR15N
- Temper170 ± 10 °C
- Soak90 ± 10 min
STEP typical parameters from process inspection records. Times illustrative; actual cycle per part specification.
Route through the plantSpecifications we control
Three numbers checked on every lot.
Tighter bands are quoted per part.
- As-quench hardness
- 89–93 HR15N, checked before the temper.
- HR15N · 5 random samples
- Effective case depth
- To the depth and limit hardness on your drawing.
- Microhardness traverse · sectioned sample
- Temper
- 170 ± 10 °C for 90 ± 10 min.
- TFC · soak logged
Typical work
Grades and parts we carbonitride.
Material grades
Plain carbon and low-alloy steels. Send the grade with your drawing.
Part types
- Pins
- Bushes
- Sleeves
- Plates
- Pawls
Questions
Asked about carbonitriding.
Why is surface hardness sometimes given in HRA or HR15N?
On a thin case a standard Rockwell C indent goes through the case into the core. Superficial scales measure the case itself. We test to the scale on your drawing.
Can you run a trial first?
Yes. A trial charge is sectioned and reported before you release production. See development trials.
Next step