For starters awesome failure as a 15" knife made all sorts of bad sounds What started as a review of very old heat treating information and a note that Brine can be used in a limited fashion on 1095 for thin sections and is likely needed for sections over a 1/4" thick I decided I would test it out some day since I have a couple of blades made with 1095 kicking around. The idea of Martempering or austempering seemed interesting and not something I had tried before. Also picked up some dry ice for doing cryo on the blade so I could get every last bit out of this chopper. Basics of experiment are Brine about 7-10% that can float a egg or slice of potato water temperature is 100F The premise is that 1095 needs to be down to 800F in 2 seconds for maximum results. However 1095 will shatter at the Martensite start temperature if allowed to reach that point after a brine quench. So the procedure was to be: 1 second to 2 seconds in Brine, long enough the bulk of the edge will just turn black 5-10 seconds in Canola oil heated to 130F, remove every five seconds and measure temperature in the ideal world. I spaced out and paused just a bit longer and as I withdrew the knife it did the tink in rapid succession so I returned the blade to the tank and let the cracking finish. It so happens the ideal temperature of 600F and don't go below temperature of 500F were not exaggerated and did not come with much of a buffer. It should have been 600F out of oil then into furnace at 500F for a few hours or simply stabilized the internal temperature allowing some stress to relax then allowed too slowly air cool below the Martensite start (Ms) temperature Once at room temperature temper at 400-450F temper, Cryogenic temper if desired, 400-450 F temper Grain structure of the knife, brownish area is from a acid dip I did after a light sanding and buffing of the blade to see if I had a Hamon. This shot was supposed to have the template for comparison but I forgot to make one before the fun started, there is about a 1/4" extra curve in the cutting edge over the original design. Interesting effect of bubbles along the spine where the ATP-641 blew off while the steel was exposed to steam and air, it happened so fast it was amazing. Little to no ATP-641 made it into the oil bath. One thing that did work well was the ATP-641. 1-wash blade in soap and water. 2- wipe down with acetone and alcohol 3-allow to dry 4-apply ATP-641 with brush. Note: it must be stirred for several minutes with a powered mixer in such a way no foaming occurs. This has to be thoroughly mixed. 5-if the ATP-641 beads off the steel anywhere then it is not clean enough, scrub and repeat. 6- if the first coat is sound allow to dry naturally or with a little heat and moving air. When dried apply two more coats with complete drying between applications. This all seems a little much but it did work after six attempts with other cleaning and layer applications that were faster. It can go faster if transferred to a tube and you simply dip the blades and allow to dry for a couple of hours. I bet if I asked I could have skipped the whole fiasco but part of me was more interested in trying something new and seeing what happens, as the daughter points out that was the same philosophy I took stepping off a 6 story cliff into a river. For the record the fall was cool, hitting bottom of the river really sucked
I have done 1095 straight in oil and straight in water. Water was a disaster o cracking, and oil worked without any cracking. My biggest issue was that one of the thin fillets i treated in oil was sitting on the anvil as i finished the rest of the batch. It had cooled enough to hold bare handed, and with no outside influence, i heard it start to tink behind me. The blade had enough stress from the quench that it tore itself apart just sitting there.
The grain looks good. Did you do any normalizing cycles? I was wondering if heating the oil to about 200°C and letting the blade sit in that would have helped reduce stress. Like letting it sit in the deep fryer. Dan
No normalizing cycles that was 1095 straight from Knifemaker.ca. The oil would have to be at 260C to stop cooling above the Ms temperature stabilized throughout then allowed to cool slowly in still air. Original plan was my quench plates in the oven at 500F (260C) for a half hour then turn it off and allow to cool slowly. I will be trying again in the future but with a smaller knife and may leave the edge at 2mm thick and polished instead of 1mm
What was your heat source for the quench?(forge or kiln) You had several things working against you. -1095 is not the best choice for a chopper(but that is kinda beside the point) -It looks as though the cross section from spine to edge is rather dramatic for this type of quench. A lot is happening during the quench and that thick spine will win most of the time. You could try quenching spine first. -today's 1095 is not the same as you would find in old files. It isn't as clean as it used to be and doesn't respond well to brine -you may have been better off with clean water. It isn't as fast as brine. Though I still think you are crazy... lol. -moving back and forth, in and out of quench mediums is creating more stress than allowing to air cool after and interrupted quench. -marquenching is hard to attain without a medium like salts or oil. liquid mediums are successful because they draw the heat out out much more efficiently than air. -1095 does not require cryo. Not to mention that acetone and dry ice is barely considered cryo. Though, I guess it is better than nothing. -That 1095 really could have used some pre HT thermal cycling. The grain could be further refined but more than that... it probably came to you highly spheroidized and a highly speroidized hypereutectoid steel NEEDS thermal cycling to form carbides and distribute the rest of that "rogue" carbon where it won't get in trouble.
I think crazy was top of the list, kind of a curious to see what would happen. Next time sticking with bar stock for experiments. Working with a evenheat oven and will be playing with normalizing in the near future when I get another bit of 1095 in stock
Had not considered normalizing the 1095 but it was the assumption it was supplied in a fine Spheroidized state, could be wrong and probably should check with Canadian Knife Supply. was going off this discussion http://www.bladeforums.com/forums/s...els?highlight=heat+treating+spheroidize+steel
So far I have used lots of 1095 from 1/16th to 1/8th thick and I have done nothing further than heating to non-magnetic, holding it there for an extra 30 seconds or so and then quenching in canola oil warmed to 130 degrees or so. Temper twice at 2 hours per cycles, cooling to room temperature in between. So far the edges have been hard and tough and I have had zero issues. Is it possible to be over thinking this?
Hahaha! This is knifemaking! Everything is overthought. Take 12% hearsay, add 31% snake oil, 40% magic and 17% is what really happened.
Yer delving into the mad scientist trying to unlock the full potential stage lol. I need much more experience with just doing it the (almost) safe way....but I did experiment with some interrupted water-oil quenching. I stopped after 3 consecutive "tinks" and decided to go back to the basics for a year or ten before I try "tinkering" again
I did an axe with an old file forge welded in as the cutting edge. I quenched it twice in 130F Canola and it wouldn’t harden, (file still bit in) so I tried an interrupted quench. 2 seconds in water then into the oil then into the kiln. Worked great. File skipped right off. -Trent
