JHCC Posted February 3, 2019 Share Posted February 3, 2019 Last Quad-State, I got a couple of yards of 3/4" round rod in O1. Yesterday, I finally got around to starting a knife, but ran into some problems which I'd appreciate some help with. In short, I got some nasty cracking while drawing out what was supposed to be the tang. Could someone please take a look at the following photos and give me an idea of what I may have done wrong? I understand that O1 can have issues with air hardening and contact quenching, that working it too cold can lead to cracking, and that working it too hot can make it crumble/cottage cheese. I've already read a couple of the other threads about working with O1, such as this one and this one. The cracks appeared while I was hammering, but I suppose it's possible they had formed earlier and only became evident during drawing out. I don't believe that I burned the metal at any point or got it anywhere near welding temperatures. For comparison, here's the tip of the preform, which has no such issues (what looks like cracking is just scale). For context, I was working with a side-blast forge burning bituminous coal. Ambient air temperature was about 40F. The anvil was not cold -- as I'd been working on some other projects previously -- but not hot, as those projects were fairly light. Hammering was by hand, not with a power or treadle hammer. Quote Link to comment Share on other sites More sharing options...
eutrophicated1 Posted February 4, 2019 Share Posted February 4, 2019 I was surprised to find how low this alloy's critical temperature is, along with how many small percentage elements comprise its makeup: Typical Chemistry Carbon 0.90% Manganese 1.25% Silicon 0.30% Chromium 0.50% Tungsten 0.50% Typical Applications Blanking Dies Jewelers Hobs Engraving Tools Paper Knives Forming Tools Taps (Hand) Gauges Trim Dies Hardening Critical Temperature: 1370F(745C). Preheat: 1250/1350F(675/730C) High Heat: 1450/1500F(790/815C), hold 10/30 minutes at temperature. Quench: Quench in oil to hand warm, 150F(65C). Temper: 350/600F(175/315C); hold one hour per inch of thickness, two hours minimum, four hours preferred. This has to be very difficult to forge out. Quote Link to comment Share on other sites More sharing options...
stressless Posted February 9, 2019 Share Posted February 9, 2019 you got it to hot n didn't keep it hot enough. low glow don't hit Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 9, 2019 Share Posted February 9, 2019 In addition to too hot and too cold, there is a narrow working range of temps for forge welding, and a seperate range for forging temps. in between those, there is a gap of DO NOT TOUCH , in addition to the occasional air hardening from working thin sections. These issues are not exclusive to O1 it is common with a few tool steels. It is all a mater of getting use to each steel we attempt to work. These temps are listed in the Spec sheets that we get when buying steels, Another reason why salvaged is always a crap shoot Quote Link to comment Share on other sites More sharing options...
JHCC Posted February 9, 2019 Author Share Posted February 9, 2019 Thanks, Steve; that makes sense. I see that Kevin Cashen's website recommends forging O1 at 1800°F/1950°F at the top end and not forging any cooler than 1550°F. Granted that lighting conditions etc. can affect color perception, that would be roughly from a dark yellow down to about a bright red. If memory serves, I started running into trouble when forging the tang section at about a light yellow. So, I guess if I take the steel out of the forge and see that it's too bright, I should just let it cool off a bit before I start to hammer? Quote Link to comment Share on other sites More sharing options...
Steve Sells Posted February 9, 2019 Share Posted February 9, 2019 yup Quote Link to comment Share on other sites More sharing options...
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