Greetings,
I just did a test that stunned me. I had a 5160 bowie blade and a 1075 bowie that I had laying around, and decided to do a steel cutting test. I sledge hammered the 5160 in to the galvanized rail, but it wouldn't go in. It rolled so much that my eyes bugged. I tried 1075, and it was able to cut a good 2 1/2", with minor, minor distortion of the area of the edge. Here's the surprising thing though: When I did a bend test, the 5160 only went 30 degrees, and snapped!! Very fine grain. 1075 went to 75 degrees, and also fine grain.
This is a mystery to me. I thought 5160 was a great steel-- I know I shouldn't be pounding knives into metal beams, but why did 1075 come out on top? The 1075 did get a differential hardening, though I am confused why the edge rolled even slightly instead of staying springy when it was only tempered at 375 degrees. With that kind of deflection, I expected it to bend farther as well? Am I not tempering my blades long enough? I feel that I should be doing less edge hardening, (more spine) and tempering at 300 degrees, but that doesn't sound right. The 5160 was a complete flunk-- that was full quenched. Should have cut better?
Maybe I just have unrealistic expectations. Thanks in advance for all answers from experts here-- this one is beyond me.
Joseph
beckerforge.com
I use 1075 quite a bit. Love it, by the way. I leave my blades harder than a lot of guys. One thing I've learned is that sudden loading from impact really can skew the results you think you would see. I've had blades roll or deform in tests where I thought they would have chipped due to the hardness. Sudden impact results can be hard to predict.
1075 is pretty tough steel too. I don't know if that plays a part in why it deformed instead of chipped. I don't know.
On the tempering, you mentioned you might not be tempering them long enough. I would think your blades would be even harder if they're not getting the full tempering.
I'm no help on the 5160. I don't use it.
Joseph,
You didn't mention how many temper cycles you used, or if you drew the spine and tang back. Also edge geometry will play a big part in the cutting ability. I used 5160 with a full quench for my JS performance test knife, and it performed great. But, I wasn't trying to cut metal with it.
Lots of good heat treat and tempering info on 5160 in the heat treat section of the forum.
Best of Luck,
Bob
I might first question how you austenized your 5160.
Seems like it got a lot of "play" early on in knife making through the 60s-70s-80s-etc., because it was everywhere to be found, and could be had by a simple trip to the junk yard.
Now, much better steels are readily available to us all. Including 1075.
I have certainly done a great deal of work with 5160, but have spent nearly the entire time with a special mill run I have of 1" square made in 1984.
One thing has held true for me every single time - 5160 works best with a 15-20 minute soak in a controlled oven at about 1520 degrees.
Lots of guys are a bit successful using forges and such to heat treat 5160, and I have as well made some knives that will work sufficiently, but to get the most out it, a long soak to get all the alloy dissolved is vital.
If you have the opportunity to use a controlled oven and get a long soak on that very same 5160 it can walk and talk with some of the best steels.
Karl B. Andersen
Journeyman Smith
There are a lot of variables and two knives tested is not exactly a telling argument. I taught the second week of the bladesmith class at Old Washington and each student used 5160. All but one blade went past the 90 degree bend. All were fully hardened (no edge hardening). That is 12 blades that exceeded the 90 test.
5160 has the addition of some chromium that will increase the depth of hardening compared to the 1075. 1075 should have a bit better edge holding based just on the carbon content but there will be some chromium carbides in the 5160. Karl's recommendation for a soak will benefit the 5160. Of course most steels benefit from a soak as long as the temperature remains constant (my preference for salt tanks).
However, while I feel the heat treat is critical we often forget about the geometry of the blade its effects on both edge holding, cutting efficiency, and deformation. Lately, on big knives I have really been trying to get down to the thinnest edge I can without deformation or chipping (two sides of the ideal tempering temperature).
It is complicated but the challenge is what makes this all worth the time and commitment.
Dan
