Heat-treating Bohler M390 with stainless tool wrap
Super-stainless with elite wear resistance and a bright polish.
Recommended SSTW grade
Grade 309 stainless foil
Bohler M390 austenitizes around 2150°F — above ~2000°F — so 309 stainless foil holds up to the heat and longer soaks without embrittling.
Shop 309 tool wrap rollsBohler M390 heat-treat reference
- Austenitizing temp
- 2000–2150°F
- Soak at temp
- Per Bohler spec
- Quench
- Plate quench, then cryo
- Temper
- 300–400°F per spec
- Typical uses
- Premium production and custom knives
- Also known as
- CTS-204P, CPM-20CV
General knifemaking guidance — always follow the steel manufacturer's published data sheet for your exact stock.
Why wrap Bohler M390 in stainless foil
At 2150°F the bare surface of Bohler M390 oxidizes and loses carbon (decarburization), leaving a soft, scaled skin you have to grind back past. Sealing the blade in SSTW 309 stainless tool wrap keeps oxygen off the steel through the soak and quench, so it comes out of the kiln bright with full hardness right to the edge — less post-heat-treat grinding, no decarb surprises.
Bohler M390 foil FAQ
Do I need stainless foil to heat treat Bohler M390?
Wrapping Bohler M390 in stainless tool wrap before the kiln prevents surface scale and decarburization, so the blade comes out clean with the carbon at the edge intact. It is strongly recommended for Bohler M390, especially for air- and plate-quenched work where the blade sits at temperature.
Which SSTW grade should I use for Bohler M390 — 309 or 321?
Bohler M390 austenitizes around 2150°F — above ~2000°F — so 309 stainless foil holds up to the heat and longer soaks without embrittling.
What temperature is Bohler M390 heat treated at?
Bohler M390 is commonly austenitized around 2000–2150°F with a Per Bohler spec soak, then plate quench, then cryo and tempered (300–400°F per spec). Always confirm against the steel mill's published data sheet for your exact stock — these figures are general knifemaking guidance.
Can I use 321 foil for Bohler M390?
321 works for many sub-2000°F heat treats, but Bohler M390 runs hot enough that 309 stainless foil is the safer choice — it tolerates the higher austenitizing temperature and longer soaks without embrittling.
Ready to heat treat Bohler M390 clean?
SSTW Grade 309 stainless tool wrap, sold by the roll and shipped from the USA.
Shop tool wrap rolls