52100 heat treat: austenitize, quench & temper chart
52100 is a spring / tool 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 52100 heat-treat schedule
Austenitize: 1500–1525°F (1500°F recommended), hold 15 min once to temperature. A controlled oven or kiln beats forge colour for hitting this window repeatably.
Quench: Parks 50. Also acceptable: Duratherm 48, Parks AAA. Never use Water, Brine, Canola oil. Fast oil quench. 52100 is bearing steel — fine-grain structure depends on prior spheroidized anneal.
Cryo (optional): About 0.5 HRC bump with LN₂; non-cryo gives superior toughness-hardness balance.
Temper: 2 passes of 1 h at 350°F for the recommended edge (~63–64 HRC). Temper twice for 1 hour. Prior spheroidized anneal (DET) improves grain refinement — Larrin documents the full prep sequence.
52100 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 |
|---|---|
| 300°F (149°C) | 64–65 HRC |
| 350°F (177°C) | 63–64 HRC |
| 400°F (204°C) | 61–62 HRC |
Target hardness for 52100 by knife type
| Use | Recommended HRC |
|---|---|
| Kitchen | 62–63 HRC |
| EDC | 61–62 HRC |
| Hunter | 61–62 HRC |
| Hard-use chopper | 60–61 HRC |
Forging 52100
Forge-friendly. Bearing steel responds well to forging; fine-grain results depend on the spheroidized anneal step.
Most common mistake
DET anneal sequence is multi-step (1700°F normalize → 1460°F refine → 1460°F → furnace cool). Skipping the anneal sacrifices grain refinement.
FAQ
What temperature do you austenitize 52100?
1500–1525°F, with 1500°F recommended, held 15 min once the steel is fully up to temperature.
What is the best quench for 52100?
Parks 50. Duratherm 48, Parks AAA also work. Never Water, Brine, Canola oil. Fast oil quench. 52100 is bearing steel — fine-grain structure depends on prior spheroidized anneal.
What HRC does 52100 reach?
61–65 HRC across the usable tempering range; about 62–63 HRC for a kitchen knife. Temper at 350°F for ~63–64 HRC.
How do you temper 52100?
2 passes of 1 h at 350°F for the recommended edge. See the chart above to pick a different tempering temperature for a harder or tougher blade.
Can you forge 52100?
Forge-friendly. Bearing steel responds well to forging; fine-grain results depend on the spheroidized anneal step.
What you need to heat-treat 52100
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 1500°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 52100; 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.