Thank you for the timely reply. I am working on / foring a 24? Machete from 5160 steel. I really do not want to put this blade through a destructive testing to prove this process. I have done that already on a 12? blade from 5160 (basically the same process) ? forged at 2000? F ? 2100? F. Then first thermal cycle with the last forge working (at 1900? F) allowed to cool in still ambient temperature. Then I brought the Heat-Treat Oven up to temp with the PID Program for the Thermal Cycling. I made three 20 minutes soaks at 1350?F and then remove from the over to air cool in still air until about 250?F. Then repeated the Thermal Cycle. After the three Thermal Cycles, I programed the PID with the Annealing Program and annealed the steel accordingly. The Rockwell check after annealing was 21-24 HRC. This allowed me to grind the blade thickness in to about .140"-.150" with 40 grit belts. There was a lot of DeCarb on this blade coming from the Annealing process above. This DeCarb really uses the belts up. Marked the Center of the blade on the edge and then ground the bevels in on the edge. Starting with 40 grit belt to about .040"-.050" thick cutting edge. Then ground with 120 grit (A160 [120 grit] 3M Trizact CF-337 DC-$7.25) blade to about .030"-.040" cutting edge. Then finished the grind with a 280 grit belt (A65 [280 grit] 3M Trizact CF-337 DC-$7.25) with the cutting edge ending up at .030"-.040" (with a short area of it at .025") thick. The spine ended up at about .130"-.140" thick with the handle area ending up at .160"-.190" at the end ... this will give weight to the handle end of the blade to help balance this long 24" blade.
I have used this process on a previous 12? blade from 5160 (Forged) with, what I thought, was good results. However, I did do a ?Soft Draw on the spine with an O/A torch) while keeping most the edge in water to ensure the heat did not draw down into the edge and affect my 58HRC. I did put that blade through the destruction testing of bending it and found that at 30? is where it failed. The grain of the steel after it broke looked very fine and I, being an amateur, was happy with the grain results from the heat-treat/thermal process I used.
I just wanted confirmation from an experienced Blade Smith to verify results of what they have seen when a ?Soft Draw? spine process was used.
I am not looking for the ABS JS test to pass here as I only wanted a Machete for use in my back yard clearing brush, one that would handle the abuse I intent to give it and still hold an edge. As I am sure I would be paying over $400 or more for one of these blades made by a Master Blade Smith.
Below is a picture of my destructive test made on the first 12? blade I made. Which was Heat treated with the heat-treat oven using a PID program. Then I had a full dip quench (tip down) in Duratherm "G" Quench Oil at room temp at about 65-70 degress F. No warpage and very little de-carb.
Quench Oil Note: Maxim compounds and blends a line of paraffin based, fast quench oils for the heat treating industry. Our "benchmark " and most popular product in this line is Duratherm "G". Duratherm G is a premium quality high speed quench oil that exhibits a GM Quenchometer speed of 10-12 seconds( Ni ball).
I do have a new design of keeping the Blade Edge cool, since it has curvature, while ?Soft Drawing? the spine after the heat-treat process on this 24? blade. Which is almost impossible to do with a pan of water on curved blades. If this works I will share with my experience/design. Not that any of the Master Blade Smiths would consider it ? since I am only an amateur.
Once again, thanks for your timely reply as I was going to heat-treat this 24? blade today and having your feedback really helps me in the direction I am choosing to go with this process.
Sorry to get so long winded ?
Picture of my first test knife can be viewed at:
http://www.ontimetooldesign.com/RJ/B...iled_30deg.jpg
Picture of my current 24" blade project can be viewed at:
http://www.ontimetooldesign.com/RJ/2...d_BeforeHT.jpg
I just finished the heat-treating process of this 24" blade. Results turned out excellent ... my rockwell checks on the spine in three places (that are parallel) produced 62-63 HRC. No warpage
and very little DeCarb (Scale).
Picture of HRC check:
www.ontimetooldesign.com/RJ/RockwellCheck.jpg
Tried getting these pictures posted here; however, the moderator must not approved the post.
....
....
...