M4 hardness

[blade man]

Hello all! I've got some M4 blanks I'm ready to send off to JT, and debating hardness. They're .074" thick, small EDC fixed blades (~3"ish blades). I'd like to bias towards toughness over absolute edge holding. What would you all recommend?

 

[DevinT]

Toughness is not going to be a issue with blades that small and that thin. ~62 hrc should be fine.

Hoss

 

[DevinT]

Note: have him use the lower end of the austenitizing range for greater toughness.

Hoss

 

[Natlek]

Hello all! I've got some M4 blanks I'm ready to send off to JT, and debating hardness. They're .074" thick, small EDC fixed blades (~3"ish blades). I'd like to bias towards toughness over absolute edge holding. What would you all recommend?

Reasonable thinking Absolute edge holding is OK ............till edge chip , then to fix it you must remove much more steel than on dull edge to get sharp again

 

[Seedy Lot]

I have had good results with M4 in a thin 4 inch fixed blade at 62rc, the knife as seen plenty of hard use. I have also been making knives out of Starrett power hacksaw blades, these are M2 at 64-65rc and I have been overly impressed with how well they handle what I ask of them. It was me looking to heat treat a 3 inch M4 blade I would lean towards higher hardness, 63 to 64rc range.

 

[JTknives]

Note: have him use the lower end of the austenitizing range for greater toughness.

Hoss

Generally I default to the lower end on most alloys unless experience has shown otherwise.

 

[Willie71]

I have had good results with M4 in a thin 4 inch fixed blade at 62rc, the knife as seen plenty of hard use. I have also been making knives out of Starrett power hacksaw blades, these are M2 at 64-65rc and I have been overly impressed with how well they handle what I ask of them. It was me looking to heat treat a 3 inch M4 blade I would lean towards higher hardness, 63 to 64rc range.

I agree with this suggestion. If toughness is a concern, go with z-wear or v4e, which is slightly tougher. Use the advantage of M4, and don’t leave performance on the table. M4 at Rc64 is about as tough as O1 at Rc60. I would recommend O1 at Rc61/62 for an edc, so Rc64 in M4 is not too brittle. I do a lot of z-wear at Rc63/64, and have had ZERO returned with damage.