15N20 heat treat: austenitize, quench & temper chart
15N20 is a simple carbon knife steel. Here is the full heat-treat schedule — austenitizing temperature, quench, cryo and a tempering-temperature chart mapping each temper to final HRC — with every number cited to the source, not guessed.
The 15N20 heat-treat schedule
Austenitize: 1450–1500°F (1475°F recommended), hold 10 min once to temperature. A controlled oven or kiln beats forge colour for hitting this window repeatably.
Quench: Parks 50. Also acceptable: Duratherm 48. Never use Water, Brine. Fast oil quench. 15N20 is the high-contrast partner for Damascus pattern welding.
Cryo (optional): Optional; not tested.
Temper: 2 passes of 1.5 h at 375°F for the recommended edge (~58–61 HRC). Temper twice for 1–2 hours. Avoid tempering above 400°F due to tempered martensite embrittlement (observed at 450°F).
15N20 tempering-temperature chart
Two-hour temper (×2), HRC after cryo where used. Pick the tempering temperature for the hardness your knife needs:
| Tempering temperature | Resulting hardness |
|---|---|
| 350°F (177°C) | 60–61 HRC |
| 400°F (204°C) | 58–59 HRC |
Target hardness for 15N20 by knife type
| Use | Recommended HRC |
|---|---|
| Kitchen | 60–61 HRC |
| EDC | 60–61 HRC |
| Hunter | 58–59 HRC |
| Hard-use chopper | 58–59 HRC |
Forging 15N20
Forge-friendly. Commonly used in Damascus pairings with 1084 / 1095 — match the soak temperature of the partner steel.
Most common mistake
Tempered martensite embrittlement zone above 400°F — do not temper above 400°F.
FAQ
What temperature do you austenitize 15N20?
1450–1500°F, with 1475°F recommended, held 10 min once the steel is fully up to temperature.
What is the best quench for 15N20?
Parks 50. Duratherm 48 also work. Never Water, Brine. Fast oil quench. 15N20 is the high-contrast partner for Damascus pattern welding.
What HRC does 15N20 reach?
58–61 HRC across the usable tempering range; about 60–61 HRC for a kitchen knife. Temper at 375°F for ~58–61 HRC.
How do you temper 15N20?
2 passes of 1.5 h at 375°F for the recommended edge. See the chart above to pick a different tempering temperature for a harder or tougher blade.
Can you forge 15N20?
Forge-friendly. Commonly used in Damascus pairings with 1084 / 1095 — match the soak temperature of the partner steel.
What you need to heat-treat 15N20
Repeatable hardness comes from controlling temperature and quench speed — eyeballing colour is how blades end up soft or cracked.
- A heat-treat oven or kiln holds the 1475°F austenitizing temperature — the single biggest factor in repeatable hardness.
- Quench in Parks 50 for the cited as-quenched hardness.
- Verify the result with a Rockwell hardness tester or hardness files — don't trust the schedule blind.
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Sources
Heat-treat schedules are the cited published values for 15N20; every furnace, quench and blade geometry varies, so verify against your own hardness testing. Getting steel to non-magnetic is not the same as reaching austenitizing temperature — use a controlled oven or kiln for repeatable results.