I come seeking some specific advice regarding a heat treatment problem. End of last year I forged a ladder pattern damascus billet and forged some hunting knives from said billet. I finished two knives from that piece of damascus so far, all rockwell tested, nothing out of the ordinary (steel combination is 80Crv2+15n20).
Now over the holidays I forged 3 additional blades from that same damascus billet and got around to hardening them yesterday. Only that two of those blades didn't harden at all. Here's my protocol which I have used for all the blades I forged from that billet:
-Normalize at 850C°/1562F (10min), let the blade come down to room temp
-Normalize at 830C°/1526F (10min), let the blade come down to room temp
-Normalize at 815C°/1499F (10min), let the blade come down to room temp
-Anneal at 760C°/1400F (30min, cool down at 300C°/h)
for the above listed steps I put each blade in a stainless foil packet to prevent decarb. Also note that the above listed steps were performed quite shortly after I forged the blades (within a day or so), the hardening process is what I did yesterday:
-Austenitize at 820C°/1508F (holding time 15min at 4,5mm blade thickness. Oiltemp was 50C°/122F)
-quench in AAA Hardening-Oil (I use a european brand of AAA hardening oil that has worked very well for me so far). Also note that my quench tank is directly next to my Evenheat, so there is as little time as possible between the kiln and the quench. My quench tank is also big enough to accomodate bigger blades, hell I can harden swords in there if I need to, so there shouldn't be a problem there.
-Temper at 195C°/383F (2x 2h)
Edit: Also, I always let my kiln run at my desired austenitizing temp for at least 45min to equalize the kiln as much as possible regarding temperature before putting any blade into the kiln.
for the hardening process I coated the blades with a thin coat of ScaleX to keep decarb to a minimum. I also did not have all of the blades in the kiln at the same time, I always focus on one blade and then I do the next one. This might be inefficient, but I seldomly harden a large amount of blades at once and I feel I have better control over the correct soak times at the correct temperature if I do one blade at a time.
So far, so boring. Usually this process gives me a blade that tests at about 61hrc and I use that combination of steels (or 80CrV2 as a monosteel) quite often...mostly actually, so I am not new to hardening them. Now here is my problem: one of the three aforementioned blades tested in that range, the other two tested between 40-50 hrc. My Rockwell hardness tester shouldn't be the problem since it correcly tests the gauged steel testing-plate provided from the manufacturer at the specified 62hrc. I have also not noticed anything out of the ordinary with my Evenheat kiln (I have an Evenheat Rampmaster 22.5Lb, which has served me really well so far).
I am also pretty confident I did not ruin my steel during forging....neither during the inital couple forge welding steps to get my pattern as well as forging the blades. As already mentioned, I forged and hardened two blades from that very billet that worked out perfectly before. I only ran into that specific problem with these three blades.
Any advice would be greatly apprechiated.
Again, that process has yielded good and consistend results for me and I really need to find out what I screwed up here or what I missed because I can't for the life of me figure it out.
Edit: Also, before testing the blades I ground off all the little bit of decarb I had and finished the flat surfaces near the ricasso I was testing to a 500 grit finish.
Now over the holidays I forged 3 additional blades from that same damascus billet and got around to hardening them yesterday. Only that two of those blades didn't harden at all. Here's my protocol which I have used for all the blades I forged from that billet:
-Normalize at 850C°/1562F (10min), let the blade come down to room temp
-Normalize at 830C°/1526F (10min), let the blade come down to room temp
-Normalize at 815C°/1499F (10min), let the blade come down to room temp
-Anneal at 760C°/1400F (30min, cool down at 300C°/h)
for the above listed steps I put each blade in a stainless foil packet to prevent decarb. Also note that the above listed steps were performed quite shortly after I forged the blades (within a day or so), the hardening process is what I did yesterday:
-Austenitize at 820C°/1508F (holding time 15min at 4,5mm blade thickness. Oiltemp was 50C°/122F)
-quench in AAA Hardening-Oil (I use a european brand of AAA hardening oil that has worked very well for me so far). Also note that my quench tank is directly next to my Evenheat, so there is as little time as possible between the kiln and the quench. My quench tank is also big enough to accomodate bigger blades, hell I can harden swords in there if I need to, so there shouldn't be a problem there.
-Temper at 195C°/383F (2x 2h)
Edit: Also, I always let my kiln run at my desired austenitizing temp for at least 45min to equalize the kiln as much as possible regarding temperature before putting any blade into the kiln.
for the hardening process I coated the blades with a thin coat of ScaleX to keep decarb to a minimum. I also did not have all of the blades in the kiln at the same time, I always focus on one blade and then I do the next one. This might be inefficient, but I seldomly harden a large amount of blades at once and I feel I have better control over the correct soak times at the correct temperature if I do one blade at a time.
So far, so boring. Usually this process gives me a blade that tests at about 61hrc and I use that combination of steels (or 80CrV2 as a monosteel) quite often...mostly actually, so I am not new to hardening them. Now here is my problem: one of the three aforementioned blades tested in that range, the other two tested between 40-50 hrc. My Rockwell hardness tester shouldn't be the problem since it correcly tests the gauged steel testing-plate provided from the manufacturer at the specified 62hrc. I have also not noticed anything out of the ordinary with my Evenheat kiln (I have an Evenheat Rampmaster 22.5Lb, which has served me really well so far).
I am also pretty confident I did not ruin my steel during forging....neither during the inital couple forge welding steps to get my pattern as well as forging the blades. As already mentioned, I forged and hardened two blades from that very billet that worked out perfectly before. I only ran into that specific problem with these three blades.
Any advice would be greatly apprechiated.
Again, that process has yielded good and consistend results for me and I really need to find out what I screwed up here or what I missed because I can't for the life of me figure it out.
Edit: Also, before testing the blades I ground off all the little bit of decarb I had and finished the flat surfaces near the ricasso I was testing to a 500 grit finish.
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