wtf is going on with this steel?

[Arathol]

NJSB are pretty solid. Seems like the maker himself is the unknown quantity.

Ok....yeah it would seems so....
On a better note, I hit the edge pretty hard today with 220, 400, 800 and right through the range ending with a white ceramic stone. Looks like whatever decarb or burned steel was on the edge wasn't all that deep and its now scary sharp. Won't know until tomorrow how long the edge will last. Still a lot of weirdness on the blade flats though, looks like orange peel almost, lots of what looks like micropitting.....

 

[John Cahoon]

Yeah I'm thinking it wasn't 1075F. Maybe he was working on a piece of 1075 steel when he answered the HT question and had a brain fart. It happens.

 

[Stacy E. Apelt - Bladesmith]

NJSB had 1084 that was highly spherodized. It requires knowledge of how to HT spherodized steel to properly harden it. We had many threads on this starting about 10 years back.
I don't know what their current spheoridizing level is. or when the maker we are talking about bought his steel from NJSB.
If he had to re-harden the blade several times to get it to harden, that would also explain the severe decarb.

Additionally, 1084 properly hardened and tempered at 400°F would be in the Rc61-62 range. Rc55-60 sounds like a guess, not a reading. If the steel was from the highly spheroidized batch, it would be much lower hardness, sometimes barely getting into the Rc50's.

 

[Taz]

Arathol, I am in East Hampton, CT! Drop me a line, I can help you out! I have the next 2 days off after today and will be in my shop.

 

[Stacy E. Apelt - Bladesmith]

Thanks Taz.

 

[Taz]

No problem! Sorry I didn't see the post earlier...I've been in a Benadryl haze this weekend. Started cleaning my garage and moving stuff around for my 2nd HT oven and must have gotten into some wood dust outside of my grinding area. Wood allergies are kicking in bad, so I spent most of the 4 day "vacation" sleeping .

Arathol, there are a ton of us knifemakers in CT, too! Several FiF winners (included 4 from the first season alone!), runners up, and those who haven't been on the show. NCCA has an active group going and some shows in Sturbridge periodically as well as Mystic, CT next Spring. Some forges run classes as well where you can forge, heat treat and grind your own knife, too.

I tried to message you, but you don't have a membership where you can get messages. You can hit me up on instagram or Facebook!

 

[Arathol]

Arathol, I am in East Hampton, CT! Drop me a line, I can help you out! I have the next 2 days off after today and will be in my shop.

Thanks for this, but maker has finally agreed to replace the knife and its going back to him today. Hopefully this was a one time issue and the replacement is better. I should have it in a few days......
We'll see, I hope its OK because I really like this knife.

NJSB had 1084 that was highly spherodized. It requires knowledge of how to HT spherodized steel to properly harden it. We had many threads on this starting about 10 years back.
I don't know what their current spheoridizing level is. or when the maker we are talking about bought his steel from NJSB.
If he had to re-harden the blade several times to get it to harden, that would also explain the severe decarb.

Additionally, 1084 properly hardened and tempered at 400°F would be in the Rc61-62 range. Rc55-60 sounds like a guess, not a reading. If the steel was from the highly spheroidized batch, it would be much lower hardness, sometimes barely getting into the Rc50's.

Hmm. that would be a problem. I have seen suppliers that recommend normalizing before HT because of this. I hope this maker has a handle on this, he says he does not do that until after..... The blade performs very well when its sharp though. Can't speak to edge holding other than it crumbled badly at first, then after a good amount of work seemed to hold up better. Its gone now so didn't really have time to see for sure.

 

[Taz]

Glad he is replacing it for you and hopefully the new one is good!

Crumbly edge could also be from overheating the edge during grinding/sharpening. It takes a few sharpening to get back into good steel.

 

[Arathol]

Glad he is replacing it for you and hopefully the new one is good!

Crumbly edge could also be from overheating the edge during grinding/sharpening. It takes a few sharpening to get back into good steel.

Yeah, that was my thought too. He used a 2x72 slack belt to do the edge, and from all appearances he leaned pretty hard on it......

 

[DevinT]

That type of blistering usually happens when you leave it in the furnace too long. It usually happens when you you bring the furnace up to temperature with the knife in it. The maker needs to preheat the furnace before putting the blade in and soak at temperature for 10 minutes or so before quenching.

Hoss