D2 Heat treat

G

goshawk

Joined
Dec 27, 1998
Messages
297
I was thinking that the info on heat treat
was cpm 3v but What I was looking for was
heat treat of D2. I would appreciate any
help. The heat treat started with ramping
in a furnace to 1990 for 30 min. then press
quench on mag table.

------------------
http://www.imt.net/~goshawk
Don't walk in tradition just because it feels good!!!!!
Romans 10:9,10
Hebrews 4:12-16
Psalm 91

 
Goshawk,
I foil wrap my blades, one per pouch. I set one oven for 1440 and put the blades in it for pre heat. The main oven I run at 1840. Once the preheat reaches temperature I transfer them to the main oven for a 25 min bake at 1840. I then air cool and sometimes open the bags while still hot. As soon as they reach room temp I put them in Liquid nitrogen for at least 4 hours, usually overnight. Then its 3 tempers at 300-400 depending on the type of knife and Rc numbers I'm looking for. I leave my shorter heavier knives harder than most for good edgeholding. My Hawkbills need to be able to flex. This is were experimenting comes into play
smile.gif

Neil

------------------
New Hawkbill Pics!
http://www.geocities.com/Eureka/Meeting/5520/index.html

 
Dr. Lathe: Please don't take exception to my comments, but, I'd like to suggest a few things: First, you'd probably be better off doing the deep freeze after the first temper. There is metallurgical data available that shows that cryo treatment before tempering coarsens grain structure. Also, really stresses the metal.
Second, I'd suggest tempering at 925-950F. this will yield the same hardness, Rc59/60, but, blade will actually have better wear resistance and toughness. Last, I always do three tempers minimum on D2, particularly when tempering at the higher temp. Press quenching is preferred for maximum quench rate. 1850/1860 might help a bit, too, to offset the foil's insulation effect-but you're probably fine at 1840.

Just my 2 cents

RJ Martin
 
I have mine professionially done (D2 that is)
Please let me know what you get out of it by doing it you self.....(Besides the satisfaction....!!!)I mean cost-wise per knife....Where do you get them RC tested after and how much per pound?

------------------
Nonmetalic G-10&CarbonFiber Knives:http://www.geocities.com/bladewiz/bladewiz.html
 
I agree with RJ Martin except for the type of quench. Way back in the beginning I used to quench D-2 and ATS 34 in 110 degree peanut oil cause no one told me back then that they were air quench steels. You may think, "gee he sure was dumb" and at that time I guess I was, but you know I can get better flex out of both steels using the oil so have gone back to it. Dumb luck sometimes helps us all.
smile.gif




------------------
old pete
 
RJ,
Your method is very close to the way our company metallurgist set up the heat treat process for large cross section dies and other large tooling. I went by his recommendations with the process I described. He felt that the knife blades being less that 1/4" thick would not have any stress problems with the "cryo first" tempering process. As long as there were at least 3 tempers done afterwards. He also reccomended the lower temper temps, (I cant remember exactly why right now).
While he has helped me with my heat treating and even rebuilt one of my ovens....His expertise is not knives. He often "shoots from the hip" with heat treating information!
I have pushed many of my knives to the limits as far as testing and have had many compliments on the edgeholding ability of my knives. We have even looked at cross sections of broken knives to get an idea of the grain structure. We make shearing dies at work that function much like a knife blade. Much data has been collected on various heat treat methods and coatings we have experimented with on them. My idea was to heat treat my knives the same way.
I will be heat treating friday and will run several of my blades using your method and start checking results. My goal is to make the best possible knife I can and always appreciate input.
Thanks,
Neil

------------------
New Hawkbill Pics!
http://www.geocities.com/Eureka/Meeting/5520/index.html

 
BTW, the issue with freezing later rather than sooner isn't one of stress, it's one of microstructure. Freezing before a temper causes grain growth, something you don't want. the purpose of freezing is to convert retained Austenite that didn't transform on the initial quench. by tempering the initially formed martensite before freezing, the micro-structure is inproved.
Why heat treat yourself? So you can do all the little things that make a big sifference-like starting the first temper when you can just barely hold the knife in your hand (150F). If a quenched blade sits at RT longer than just 2 hours, subsequent response goes all to hell. What do you think your heat treater does when your blades come out of the furnace at 5:00PM?
He goes home and tempers them in the morning!
Plus, I can Rc check between every step, and, adjust temperatures accordingly. This helps me hit my target Rc almost exactly every time.
Also, I quench between Aluminum plates, and obtain a faster quench rate than backfill with N2 gas, often used in a vacuum furnace. So, there are a few advantages to doing it yourself, aside from the satisfaction. Of course, it costs more, but, worth it.

RJ Martin
 
RJ,
I only work with material that I can heat treat myself. I just printed your last two posts to show the "expert" at my full time job! I have plenty of aluminum for the press quench process. That is something that I can apply at work on some of our longer shearing blades!
I appreciate your suggestions and WILL try everything you have mentioned. What would be the best way of testing my results other that Rc?? Would looking at a broken test piece reveal a difference in grain structure?
Thanks again
Neil


------------------
New Hawkbill Pics!
http://www.geocities.com/Eureka/Meeting/5520/index.html

 
You must log in or register to reply here.
Back
Top