Here are some basic heat treating instructions for several common knife steels. These instructions are based primarily off of internet sources, particularly Kevin Cashen’s page, but also from various Bladeforums posts and my own experience in working with most of these steels. There are as many heat treat recipes as there are knifemakers, but in general, the information below represents the way I do it.
Jason’s Simple Heat Treat Sheet
Here’s the downloadable version of this file: http://www.frycustomknives.com/wp-content/uploads/2013/10/Heat-Treat-Handout.docx
1080/1084- The best steel for simple heat treating. Available at www.njsteelbaron.com. If stock removal, no normalization required. If forged, normalize x3 at decreasing heats. To harden, heat to a little past nonmagnetic (1500 F if you have temp control), short soak maybe 5 minutes, then quench. Quench oil should be canola, vet grade mineral oil, or a fast commercial quench oil. Temper one hour at 400, cool then 450 for another hour for RC 58-60.
1095- Not the same as 1084. The extra carbon makes heat treating more complex. Heat to 1500, soak 10 minutes. Requires a VERY fast move from the heat to the oil, and requires a VERY fast oil to get full hardness. You can make a “good” knife out of it, but it is hard to make a “great” knife without good temp control and fast commercial quench oil.
O1- Deep hardening alloy steel. Easy to make a “good” knife, as it hardens well in just about any oil, but requires a controlled soak to make a “great” knife. Normalize x3 if forged, then 1500 F for 10 to 30 minutes. Do not overheat after normalization. Quench in any “medium” oil. Canola, mineral oil, transmission fluid, etc.
5160- High carbon alloy steel. Reputation for toughness. 5160 makes good springs, but you cannot assume all springs are 5160. Normalize x3 after forging. To harden, heat to 1525, short soak, then quench in any medium oil.
Other steels, but you can’t do these in a forge
D2– High carbon tool steel. Abrasion resistant, semi-stainless. Hard to sharpen, but holds an edge a long time. Foil wrap, 1850 x 20 minutes, plate quench, dry ice cryo. Temper 450 to 600 depending on as quenched hardness.
154 CM/ CPM 154/ ATS 34– Stainless steel. Basically 440C plus vanadium. Foil wrap, 1950 x 20-30 minutes, plate quench, dry ice cryo. Temper 450 to 550 depending on as quenched hardness
What to do with steel when you don’t know what it is
You can’t assume you know what it’s made of just by looking at what it was used for. The charts are wrong. You need some experience or luck to make a “great” knife out of mystery steel. Most of us are better off just buying known steel. Don’t forget “time is money.” If you take 3 hours and 3 heat treat cycles to get the steel dialed in right, you could have just bought 1084 and done it once. On the other hand, your grandpa’s file, springs off a ’56 Ford, or a plow off of the old homestead can be more interesting.
Here’s my basic method for figuring out if a steel will make a knife or not.
- Is it stainless or carbon? If it’s stainless, it’s likely too complex to get right by trial and error.
- How much carbon is in it? Do a spark test. If you don’t get “frizzy” sparks, it won’t harden enough to make a knife.
- Try a hardening cycle. Use a thin piece. Run it at 1500 x10 minutes and quench in fast oil. Try and break it. If it bends, it won’t make a knife. If it breaks, look at the grain. It should be gray and fine with the grains barely visible. If it breaks and has fine grain, make a knife out of it. It may not be great, but it will be usable.