80crv2 heat treat issue

V

Vincent Price

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Feb 28, 2020
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I am heat treating a few knives I've Forged out of 80crv2. I am soaking them at 1535 for 15 minutes. I let them come up to that temp slowly with the oven also. Then quickly quenched in Parks 50. They aren't hardening. I clean the carb off and test with my RHC files and they are testing at 40 to 45 right out of the quench before any tempering cycles. Any ideas?
 
You have to grind/sand away all the decarb before testing. 15 minutes will give a fair layer of decarb.
I would take one of the blades and go to the grinder and see if it showers sparks after it gets through the decarb. Then test it with your files.
 
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Vincent Price said:
I am heat treating a few knives I've Forged out of 80crv2. I am soaking them at 1535 for 15 minutes. I let them come up to that temp slowly with the oven also. Then quickly quenched in Parks 50. They aren't hardening. I clean the carb off and test with my RHC files and they are testing at 40 to 45 right out of the quench before any tempering cycles. Any ideas?
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How long it takes to your oven to get to 1535 ? If steel is not protected you will have a lot of decarb. that way .
 
Yeah most folks, for good reason, bring the oven up to temp, let it soak at temp for a short while, then put the knife in. After you close the door and the temp comes back to 1535 start your soak, 10min should be fine. The decarb layer will be thin with that method.
 
It takes my oven roughly 30 minutes to get to the 1500 range. It's an Evenheat lb27 working on a 220v circuit. After one of the knives totally cooled I took it to the grinder with a 120 grit belt and gave it a few passes under a wheel and knocked the carb off one side. Back down to clean steel it tested in the same 45 hrc range. I tested a knife I heat treated over the weekend in 1095 and it's in the 55 to 60 range.bof course I've already tempered it back some. On another note I generally let the oven come to temp empty but had this same problem yesterday with this 80crv2 so I decided to let them come to heat all the way with the oven and then soak because I though maybe the crv2 was different since I not too familiar with it yet. So far I'm not impressed but I realize it's probably something I'm doing incorrect even though I can't think of anything off hand.
 
Another thing to consider is that your HT oven likely shoots past 1535 to get there. I see a similar issue with my tempering oven (a dreadful little toaster oven). I suppose it's inherent with any kind of oven.

Also, where did you get the steel from?
 
If think it would still get hard on quench as long as it's over 1525 or so on quench. I got this bar of steel from Pops Knife Supply.
 
Pops gets their 80crv2 from New Jersey Steel Baron.

Did you run normalizing cycles? I understand this is rather important for steel from NJSB.
 
Agree with N.W.- Do normalizing cycles first. 3 rounds of: 1500 for 8 minutes then let cool to room temp. Then do your hardening after that.
 
I had trouble at first with 80crv2 as well back when it first came out. I was using a 1500 with 10 minute soak into parks. couldnt get anything above low 50's... Then I started doing a 1650-1550-1450 normalizing cycle and that fixed it.
 
Yeah, 1500F is not hot enough for normalizing. You need to get to ~1650F to normalize most of the low alloy carbon steels. After normalizing, then thermal cycle around 1500 3 or 4 times to help refine the grain. Most of the carbon steels that NJSB sell are very heavily spheroidized from the mill. I think I read where they were going to address that issue recently, but I haven't used steel from them in a few years. 1535F is a little hot for an austenitizing temp. 1500F is better.
 
samuraistuart said:
Yeah, 1500F is not hot enough for normalizing. You need to get to ~1650F to normalize most of the low alloy carbon steels. After normalizing, then thermal cycle around 1500 3 or 4 times to help refine the grain. Most of the carbon steels that NJSB sell are very heavily spheroidized from the mill. I think I read where they were going to address that issue recently, but I haven't used steel from them in a few years. 1535F is a little hot for an austenitizing temp. 1500F is better.
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every oven is different to an extent but in my experience 1500° is to cold. You start to get hardening issues. We find that the manufactures recommendation of 1545°f-1615°f to be spot on. We sit at the cool side of that but the steel always preforms great.

on your forged blade did you grind the blade before heat treating or did you heat treat the as forged blade? Decarb from heat treat on clean steel will usually be under .01 depending on soak time. Most times it seams to only be a few thousands thick (not counting scale). But if your forging a blade the decarb will be tuck from the time spent at forging temps.
 
Kentucky said:
I had trouble at first with 80crv2 as well back when it first came out. I was using a 1500 with 10 minute soak into parks. couldnt get anything above low 50's... Then I started doing a 1650-1550-1450 normalizing cycle and that fixed it.
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A single 1650°f soak to temp and air cool will give you a proper industry standard normalization. Stepping down in temps is used to refine grain size on blades that have spent a lot of time at elevated temps. As seen from forging or Damascus manufacturing.
 
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