Heat treat problem?

[Temujin H-Pinchers]

I recently finished a razor made out of 1095 steel. For the hardening I heated to 1480 and quenched in oil. Tempering was at 450 degrees f 2x2 hours. I can't get this thing to really sharpen up. I get to a point where it seems to take an edge, passes the thumb pad test, but it won't shave, or will shave intermittently along the edge. I checked with a loupe and the edge has a uniform scratch pattern and no chips, but when I kind of scraped the edge with my thumb it seemed that the edge would just crumble away. I thought maybe my blade didn't harden so I filed the edge and the file would just skate over unless I really used force to dig in. I was wondering if maybe the blade is too hard or brittle? Help much appreciated.

 

[FredyCro]

Have you tried the brass rod test?

 

[Joshua Fisher]

It would help to walk through your sharpening process, to me it sounds like you put the edge on initially with a coarse belt and you have not fully removed the burr or apexed the edge. On a fine stone like a 1000 grit water stone or black Arkansas stone place the knife where you think you should be sharpening then raise the angle just slightly think about raising it only a degree or two so you are only contacting the apex of the edge and not the heel of the shoulder, make several passes at the raised angle on both sides back and forth then strop on leather with some honing compound, if that fixes your problem then you can go back to the stone and lower your angle back to thin the shoulder down and improve cutting performance. Other things to consider, 450 seems too high for 1095 unless you wanted it softer, 400 would work just fine and give a bit better hardness and you don’t say what oil you used 1095 needs a fast oil like parks 50 or water, you may not have a proper heat treat which would make it difficult to sharpen if you have hard and soft spots. One last thing make sure you are using a new file I have found that round chainsaw files work best, I buy them in a pack of 3 and switch to a new file every so often as the one I’m using wears out otherwise if the file is full it may skate even at lower hardness.

 

[Temujin H-Pinchers]

It would help to walk through your sharpening process, to me it sounds like you put the edge on initially with a coarse belt and you have not fully removed the burr or apexed the edge. On a fine stone like a 1000 grit water stone or black Arkansas stone place the knife where you think you should be sharpening then raise the angle just slightly think about raising it only a degree or two so you are only contacting the apex of the edge and not the heel of the shoulder, make several passes at the raised angle on both sides back and forth then strop on leather with some honing compound, if that fixes your problem then you can go back to the stone and lower your angle back to thin the shoulder down and improve cutting performance. Other things to consider, 450 seems too high for 1095 unless you wanted it softer, 400 would work just fine and give a bit better hardness and you don’t say what oil you used 1095 needs a fast oil like parks 50 or water, you may not have a proper heat treat which would make it difficult to sharpen if you have hard and soft spots. One last thing make sure you are using a new file I have found that round chainsaw files work best, I buy them in a pack of 3 and switch to a new file every so often as the one I’m using wears out otherwise if the file is full it may skate even at lower hardness.

I didn't put an edge on with the belt, I never grind into an apex with a belt on a razor. Tempering temps came from the Cashen site, hardness should be around 61 which is fine. I'm using canola oil for quench, from looking about it seems water should never be used.

 

[Joshua Fisher]

I didn't put an edge on with the belt, I never grind into an apex with a belt on a razor. Tempering temps came from the Cashen site, hardness should be around 61 which is fine. I'm using canola oil for quench, from looking about it seems water should never be used.

1095 really needs a fast quench, it is a water quenching steel so if you want to use oil parks 50 is best as its speed is comparable to water. How thick was the razor before heat treating? Did you quench full thickness then grind the bevels? theres a lot of variables and not using the proper quench oil can effect if the blade hardened properly. At the very least the canola oil should be heated to about 120f. Perhaps try taking the edge off completely with just a couple passes to flatten the edge on a 1000 grit stone then reset the edge and re sharpen. Again not being sure of your sharpening process it’s hard to give advice but it should shave well at 1000 grit, if it’s not shaving at that stage going up in grit won’t solve the issue. Make sure the stone is flat and your applying even pressure.

 

[Temujin H-Pinchers]

1095 really needs a fast quench, it is a water quenching steel so if you want to use oil parks 50 is best as its speed is comparable to water. How thick was the razor before heat treating? Did you quench full thickness then grind the bevels? theres a lot of variables and not using the proper quench oil can effect if the blade hardened properly. At the very least the canola oil should be heated to about 120f. Perhaps try taking the edge off completely with just a couple passes to flatten the edge on a 1000 grit stone then reset the edge and re sharpen. Again not being sure of your sharpening process it’s hard to give advice but it should shave well at 1000 grit, if it’s not shaving at that stage going up in grit won’t solve the issue. Make sure the stone is flat and your applying even pressure.

I actually did end up just grinding the initial edge off and resetting a new bevel, thinking that maybe I had a layer of decarb at the apex but even after this I was getting the same problems. I had another blade where I had hardened at full thickness so I just went and tested with a file, it seems like some points along the edge it is hard and the file skates and other places it digs in, like the blade didn't harden evenly.

I have read so many times not to water quench 10xx steels. Then I just looked at Admiral Steel and it says to water quench 1095. I did water quench a test blade of 52100 some time ago and it turned out fine. There is so much contradictory information out there.

 

[Joshua Fisher]

Certain 10xx steels don’t need a fast quench, but 1095 does. 52100 doesn’t need a fast quench the chromium makes it a deeper hardening steel so canola or parks AAA works best for it, water is a harsh quench medium which is why a lot of people use parks 50 but if done right water or brine will work very well. There are quite a few people that only use water and are very successful with it. But if your just starting off expect a lot of cracked blades until you dial in your temperatures and process and even then you may lose some. Personally I’d just use parks 50 unless I was trying to get a hamon from 1095 or w2.

 

[lotfong]

I actually did end up just grinding the initial edge off and resetting a new bevel, thinking that maybe I had a layer of decarb at the apex but even after this I was getting the same problems. I had another blade where I had hardened at full thickness so I just went and tested with a file, it seems like some points along the edge it is hard and the file skates and other places it digs in, like the blade didn't harden evenly.

I have read so many times not to water quench 10xx steels. Then I just looked at Admiral Steel and it says to water quench 1095. I did water quench a test blade of 52100 some time ago and it turned out fine. There is so much contradictory information out there.

Water quenching is tricky. For whatever it saves in upfront costs it catches back in logistical hassle and unforgiving methodical process. Unless you are in for a crazy hamon on some shirogami steel or want to get the hardest possible blade without cryo, I'd say go with parks 50. Does the job so well. Without hassle. I personally water quench some steels when I make very thin, very hard kitchen knives (26c3, 1095, silver steel, aogami 2) as I figured out a good process dialed in to sucessfully "not mess up" blades this way and I feel a difference when I sharpen water quenched blades on natural stones, it does deburr easier. But I am also a kind of sharp freak and I am absolutely able to get almost the same results with parks50, it is just me playing around for the sake of it. I must point out also that I do it only in san mai blades with many preparative steps, if I was working with a monosteel blade and just austhenitizing and dunk it in water I'd have very few chances of making a blade not snap in half. @HSC /// has done a nice thread about his heat treat methods for hitachi laminated steels that sums it up proper, I'll try to find the link for it. Personally I use a heat treat oven to make sure I get temps right and do normalizing steps finishing with a DET anneal before aust. But if you can pull it off by eye hats off to you!!
EDIT: I also use a more conventionnal tempering process with a toaster oven, 2h twice at desired temperature.

 

[lotfong]

https://www.bladeforums.com/threads...eel-heat-treat-process.1397121/#post-16217424

 

[john april]

are you feeling a burr when you are sharpening? have you been able to get other knives shaving sharp so no hairs are left behind ? just trying to rule out one thing, before chasing another.

 

[lotfong]

are you feeling a burr when you are sharpening? have you been able to get other knives shaving sharp so no hairs are left behind ? just trying to rule out one thing, before chasing another.

I get pretty much the same excellent final results with water and parks, it's just that deburring is a bit easier with water quenched, feels a little bit crisper but maybe thats just me, but I know others have had a similar experience. Maybe it has to do with retained austenite, probably that cryo does mitigate the difference to imperceptible levels. In any case I wouldn't rule out parks50 for these reasons.

 

[lotfong]

Also I have no definitive way to validate my results but on 26c3 for example I'd bet that it gets around a point harder with water the way I do it. I do Larrin's book 26c3 recommended normalizing, grain refining and DET temperatures and process in my oven, but I use a lower aus. Temp at 1445f for water quenching instead of 1475f, same 10min hold at temp. I have the Tsubotan colored rockwell files and the 65hrc still slides on the steel after two 2h 360f tempers whereas parks it starts to bite around 315-325f. Both cases are still resulting in steel hard beyond most needs so I 'd go the most convenient way. So far on over 70 blades I've lost only 4 blades to the water while I lost none to parks. Failure in water was due mostly by skipping the low temp anneal before aust. It makes hell of a difference, it also limits distortions overall.