ApexUltra heat treat: austenitize, quench & temper chart
ApexUltra is a powder metallurgy 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 ApexUltra heat-treat schedule
Austenitize: 1525–1625°F (1575°F recommended), hold 10–15 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 or medium oil quench. ApexUltra is a high-carbon non-stainless designed for edge retention without the powder metallurgy stainless complication.
Cryo (optional): Cryo is optional — 0.5–1 HRC bump depending on austenitize temp and prior structure.
Temper: 2 passes of 2 h at 400°F for the recommended edge (~62–63 HRC). Temper twice for 2 hours. 300–450°F all viable; no drastic toughness drop down to 300°F.
ApexUltra 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) | 65–66 HRC |
| 350°F (177°C) | 63–65 HRC |
| 400°F (204°C) | 62–63 HRC |
| 450°F (232°C) | 61–62 HRC |
Target hardness for ApexUltra by knife type
| Use | Recommended HRC |
|---|---|
| Kitchen | 63–64 HRC |
| EDC | 62–63 HRC |
| Hunter | 61–62 HRC |
| Hard-use chopper | 61–62 HRC |
Forging ApexUltra
Forge-compatible per Larrin: quench from non-magnetic in oil for forge-only HT. Furnace path requires the normalize → grain refine → anneal sequence first.
Most common mistake
High-carbon non-stainless — corrosion-prone. Forge path requires the normalize / refine / anneal pre-sequence even though forge-compatible.
FAQ
What temperature do you austenitize ApexUltra?
1525–1625°F, with 1575°F recommended, held 10–15 min once the steel is fully up to temperature.
What is the best quench for ApexUltra?
Parks 50. Duratherm 48, Parks AAA also work. Never Water, Brine, Canola oil. Fast or medium oil quench. ApexUltra is a high-carbon non-stainless designed for edge retention without the powder metallurgy stainless complication.
What HRC does ApexUltra reach?
61–66 HRC across the usable tempering range; about 63–64 HRC for a kitchen knife. Temper at 400°F for ~62–63 HRC.
How do you temper ApexUltra?
2 passes of 2 h at 400°F for the recommended edge. See the chart above to pick a different tempering temperature for a harder or tougher blade.
Can you forge ApexUltra?
Forge-compatible per Larrin: quench from non-magnetic in oil for forge-only HT. Furnace path requires the normalize → grain refine → anneal sequence first.
What you need to heat-treat ApexUltra
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 1575°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.
- Wrap in stainless tool-wrap foil to stop decarb and scale at high austenitizing temperatures.
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Sources
Heat-treat schedules are the cited published values for ApexUltra; 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.