Cru Forge V Toughness Testing

jdm61 said:
What Hoss said. I have used #50 for thicker blades, but I had a thin, partially beveled kitchen knife blade absolutely explode after the quench. I immediately ordered some McMaster-Carr AAA equivalent.
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This is 1/4" thick material.
 
Thanks for the leg work on this, been using this steel for 4+yrs and passed my ABS JS performance test with it and all my testing drops right into your graphs. Something I haven't done is play with the dry ice slurry for RA, but I will. The oil that works best for me was suggested by Karl Andersen, GLOC Quench A. Great lakes Oil Company. This oil also works great with 80crv2.
 
I know. For that kitchen knife, I forged .250 stock down to around .090. I bought over 300 pounds of the stuff when it first came out and still have over 200 left.
 
If ever want to part with some let me know. I like it mixed with L6, as well as alone. I don't hand polish it anymore though just belt to A65 then ceramic tumble.
jdm61 said:
I know. For that kitchen knife, I forged .250 stock down to around .090. I bought over 300 pounds of the stuff when it first came out and still have over 200 left.
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I'm surprised no one cares that triple quenching didn't work.
 
Larrin said:
I'm surprised no one cares that triple quenching didn't work.
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This is old news to some of us as other steels showed no improvement. Proper grain refinement prior to quenching is all that is needed. I personally appreciate the confirmation, but wasn't surprised. This is another myth that needs to die.
 
At least one very smart guy has said that triple quenching essentially is grain refinement for people using simple HT gear.
 
R.Rock said:
If ever want to part with some let me know. I like it mixed with L6, as well as alone. I don't hand polish it anymore though just belt to A65 then ceramic tumble.
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I have been chatting with Russ and others about CFV/L6 san mai to stretch out my supply. I have like 150 feet of the 1.25 wide stuff and another 60 or so of the 2 inch and a couple of bars of the orphan 1 inch. What HT regimen have you been using for the CFV/L6 blend? On paper, it looks like 1500/400F would work.
 
Your Temps should work, with my setup it is
1510/420 with 2 2hr temper cycles, finishes @ 61.5-62 rc. I will use dry ice slurry on the current batch I'm assembling to see if final rc bumps up a bit, but very happy with what I'm getting now.
 
Do some coupons between 1450 and 1520. Should give you a good idea where you need to be. I would think 1475 to 1490 will be the sweet spot. 15-20 min soak.
 
I Did, as I said in MY setup, it's the Temps I posted
Your results are guaranteed to be different.
 
jdm61 said:
At least one very smart guy has said that triple quenching essentially is grain refinement for people using simple HT gear.
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I think I know who you are talking about, and there are a lot of "if's" to get right. The quench adds unneeded stress to the process. Just cool to black (or when magnetic), except the last cycle, and quench at black.
 
Here are the toughness numbers for changing forging temperature. Lower forging temperatures can lead to less grain growth, but may be less effective for breaking up carbide structures. The forging temperatures are set as much for hot workability as they are for improving properties, so it is hard to know what the optimum ranges are. For longitudinal toughness the differences appear to be correlated with hardness, as the 1700°F forging temperature led to increased hardness for some reason, perhaps simply random. For transverse toughness, there appears to be a slight increase in toughness by going to lower forging temperatures, but again this may simply be experimental standard deviation. In conclusion, while I can't comment on higher than 2000°F, the forging temperature for this steel can be set according to convenience, generally, without worry for excessive grain growth leading to a decrease in toughness. However, if one is forging a knife out with many reheats and little reduction, the situation may be different.

oqTnPZF.png
 
Larrin said:
Here are the toughness numbers for changing forging temperature. Lower forging temperatures can lead to less grain growth, but may be less effective for breaking up carbide structures. The forging temperatures are set as much for hot workability as they are for improving properties, so it is hard to know what the optimum ranges are. For longitudinal toughness the differences appear to be correlated with hardness, as the 1700°F forging temperature led to increased hardness for some reason, perhaps simply random. For transverse toughness, there appears to be a slight increase in toughness by going to lower forging temperatures, but again this may simply be experimental standard deviation. In conclusion, while I can't comment on higher than 2000°F, the forging temperature for this steel can be set according to convenience, generally, without worry for excessive grain growth leading to a decrease in toughness. However, if one is forging a knife out with many reheats and little reduction, the situation may be different.

oqTnPZF.png
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To make sure I understand, is this forging, then heat treat with no grain refinement cycles?
 
So Larrin, if I'm reading correctly, those of us without precise temp control of our forge can feel pretty safe with this steel because it looks to basically behave fairly similar anywhere in that 1550-2000 range. Is that the correct interpretation?
 
Willie71 said:
To make sure I understand, is this forging, then heat treat with no grain refinement cycles?
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Yes they all received the same basic heat treatment after forging which was not a multiple quench.
 
lanternnate said:
So Larrin, if I'm reading correctly, those of us without precise temp control of our forge can feel pretty safe with this steel because it looks to basically behave fairly similar anywhere in that 1550-2000 range. Is that the correct interpretation?
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Yes, at least for the forging part.
 
Here are the summary results showing toughness vs rockwell hardness. Despite a range of different heat treatments with different austenitizing temperatures, tempering temperatures, forging temperatures, multiple quenching, etc. by far the greatest factor controlling toughness was rockwell hardness. Therefore, the starting point with optimizing any knife made with CruForge V or a similar alloy would be to try different hardnesses to see what minimum toughness is required for the application. Further optimization would be secondary.

FhMF3Di.png
 
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