Cruforge V heat treatment discrepancies?

BloodrootBlades

BloodrootBlades

Joined
Nov 29, 2011
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I bought some Cruforge V from Knife and Gun finishing supplies but when I went to heat treat it it hardened to HRC 66-67 instead of 62 as the data sheet suggests it will and the hardness/tempering temperature relationship is very different (i.e. HRC 63 at 500F instead of 58. . .). Of course this is better than expected, but I'm questioning if it really is Cruforge V. It deep hardens and works like I would expect. From the alloy composition (1.05% Carbon, .75% V, .75% manganese, .5% Chromium) I would expect it to reach mid/high 60's HRC like it did and not top out at HRC 62. Have any of you who have worked it noticed this, or does it tend to stick to the Datasheet relationships?

I did a 10 minute soak at 1500F and quenched in oil.

~Luke
 
Are your RC readings taken on clean steel, or on the scale from heat treating? I've had high readings before that were just the result of HT scale. Can't comment on Cruforge specifically.
 
I have made quite a few knives from Cru forge and what i have found is that because of the V content you really have to experiment to what works for you in your shop. I personally soak for 5 to 10 minutes at 1475 (depending on blade thickness) and quench. Then the first temper is 1 1/2 hours at 425, do a rockwell test and then adjust from there. I typically temper Cru Forge 3 times. As quenched hardness hovers around 67 and i like it to end up at 58 to 59.
 
When Cru V first came out I called Crucible and talked to the metallurgist who worked with Dan Farr to create this wonderful steel.
He told me to "get it really hot and quench it in something wet".
Because of the alloy - Cru V is not too particular what you do with it.
Nowhere on the spec sheet does it give an as-quenched hardness.
It does, however, recommend a double temper, and at 350, the resultant hardness is 62.
That is not as-quenched hardness.
To double temper down to 62 would suggest a higher hardness to begin with. ;)

It does not suggest a "soak" either.

It only says to: "Austenize - heat to 1500-1550. Equalize. Quench in oil."

 
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This is what Dan Farr sent me back in 2009:
"My heat treat schedule
1 - forge to shape, heat to red and stick in vermiculite.
2 - rough grind/ mill shoulders
3 - normalize 3 times. cool to room temp between heats.
4 - heat in furnace at 1500 for 10 minutes. quench in oil.
5 - cool to room temp, put in freezer until cool then in Liquid N2 overnight.
6 - 2 hour temper at 410
7 - use torch to draw back to blue with edge in water. cool to room temp. repeat for 3 times total.
8 - 2 hour temper at 415
9 - 2 hour temper at 415-425"
 
Since Dan is pretty dependable, and was in on the creation of this steel, it just goes to show you how easy this steel is to get along with, as his process does not precisely follow Crucible's.
Do notice that neither he nor Crucible specify SPEED of oil - just "oil". :D
And with only enough heat to "equalize", it will give you a blade of 62RC with a 350 temper.
Nice stuff. :thumbup:
 
Oh it's awesome stuff! So easy to work it's ridiculous for its performance. I wasn't picky about the oil as I read thoroughly about the steel before I worked it, but it was warm canola and therefore quite fast. Shouldn't matter there though but I thought it might help to have a faster quench for RA reduction considering the C-content if it's not picky one way or another. I agree that they didn't publish the as-quenched data, but at 300F it didn't drop but 1-1.5 points from 67. The tester was calibrated. The grain size on it is amazing with a triple normalize after careful forging/reducing heats and quench. Beautiful stuff. It is tough enough at 63 that it will make a sick laser gyuto chef knife that doesn't have to be coddled, which is my purpose for it.
 
Apparently the forum doesn't like longish replies right now as I had to cut it in over half to post. The essence of the rest of what I was going to say was that I think Karl is right-on and that with no soak it must have a lower hardness value. I've experienced this with 1095 and other hypereutectoids so it would make sense. If soaked or temps are increased more carbon can come into solution.
 
Jason Fry said:
Are your RC readings taken on clean steel, or on the scale from heat treating? I've had high readings before that were just the result of HT scale. Can't comment on Cruforge specifically.
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That definitely affects the reading, as does a lot of things, including surface roughness and angle of the steel to the indenter. I've been fooled by decarb before by example when I didn't grind all the way through it before I took the reading. I grind the blade down and take it to a A160 polish. You're supposed to take it to 400 grit but I've noticed no differences on my particular machine between the two, though there's definitely a difference between 60grit and A160- an underestimation of true hardness by several points due to the rough surface of the steel at 60 grit and easier indenter penetration. I also do 3 or more reads and average in case of decarb or other factors that could give me false readings. They're typically within a point. I also test every blade and both Cruforge blades were within the 1 point tolerance of the machine from each other.
 
I just started forging with some of this steel, and it seems brittle in forging. I've had a couple of splits when forging points. Even when I work it really hot and/or go with lighter blows from a smaller hammer, it still splits. Any ideas?

Haven't taken any to the point of HT yet, but the data suggests a slower quench. I was planning on using AAA, but the above posts seem to suggest parks 50 with that carbon content, an advice here?

Thanks in advance.
 
Karl , the 10 min is the soak. Fairly short as it is it still is needed to dissolve the carbides.
 
Slow oil is fine and it doesn't need Parks 50, AAA would be great. I have not had the brittleness problem at all with this steel, quite the contrary compared to W1 or 1095. I didn't forge it really hot, perhaps you're overheating it, that's more likely to cause splits than working it in the 1500-1700 range. This steel is very easy to HT in terms of quench, not picky at all.


tss1004 said:
I just started forging with some of this steel, and it seems brittle in forging. I've had a couple of splits when forging points. Even when I work it really hot and/or go with lighter blows from a smaller hammer, it still splits. Any ideas?

Haven't taken any to the point of HT yet, but the data suggests a slower quench. I was planning on using AAA, but the above posts seem to suggest parks 50 with that carbon content, an advice here?

Thanks in advance.
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BloodrootBlades said:
Slow oil is fine and it doesn't need Parks 50, AAA would be great. I have not had the brittleness problem at all with this steel, quite the contrary compared to W1 or 1095. I didn't forge it really hot, perhaps you're overheating it, that's more likely to cause splits than working it in the 1500-1700 range. This steel is very easy to HT in terms of quench, not picky at all.
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I'm not doubting your knowledge, nor do I intend any disrespect. I too have had issues with brittleness with this steel in forging. The CruForge data sheet suggests forging temps at or above 1600, and my issues typically occurred when the steel was below that temp. But you say that it moves fine at normal forging temps? I'm wondering if a bad batch, or mislabeled stock, somehow made it to some of us. This steel seemed very promising, I just can't figure it out yet.

I do know one thing; this has been much more difficult for me to forge than 1095. Again, not doubting you. Instead, I'm curious what I may be doing wrong.
 
RSKT said:
I'm not doubting your knowledge, nor do I intend any disrespect. I too have had issues with brittleness with this steel in forging. The CruForge data sheet suggests forging temps at or above 1600, and my issues typically occurred when the steel was below that temp. But you say that it moves fine at normal forging temps? I'm wondering if a bad batch, or mislabeled stock, somehow made it to some of us. This steel seemed very promising, I just can't figure it out yet.

I do know one thing; this has been much more difficult for me to forge than 1095. Again, not doubting you. Instead, I'm curious what I may be doing wrong.
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I just haven't experienced what you're mentioning. I gave the forging range I typically use and I often probably go a little too low during straightening and minor thinning, but I have not had any problems with it splitting. It doesn't seem harder to forge to me than any other steel with the same approximate carbon content, but that's a hard thing to judge, perhaps it is. I find that the size stock overwhelms my ability to feel fine differences and the Cruforge I have is a little thicker than many other steels I use, so it does feel a little harder to move, but not that I could tell over the difference in thickness. Best,

~Luke
 
Thank you very much for your insight. I'm going to give it another go this weekend.
 
RSKT said:
Thank you very much for your insight. I'm going to give it another go this weekend.
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You need more heat. Although cruforgev isn't hard to move under the hammer, it's nowhere near as easy as any of the 10 series steels.

You'll love it - best forging steel out there for knifemaking.
 
I would say that it might be similar to O1 under the hammer. Nothing like this 115W8/15N20 mix that I have been messing with today. :eek:
Matthew Gregory said:
You need more heat. Although cruforgev isn't hard to move under the hammer, it's nowhere near as easy as any of the 10 series steels.

You'll love it - best forging steel out there for knifemaking.
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