CREATING A BLADE THAT WILL PASS THE ABS JS PERFORMANCE TESTS
Choosing the proper steel is a must in order to pass the ABS JS test. I highly recommend 5160. Don't be fooled by it only having 60% carbon. With proper heat treating it will easily pass all phases of the test. I will take you through step by step, explaining the manner in which I would produce a blade to pass the ABS Journeyman Smith test with 5160 steel.
FORGING: Either 1 ¼” or 1 ½” X ¼” is the best size to start with for a test blade. Begin forging with the highest heats you intend to use. Then progressively reduce the heats throughout the forging process. Pay close attention, and do not let yourself be distracted from the forge! This is where most people let their mind wonder and without realizing it, let the blade overheat, which causes the grain to grow dramatically. The reducing heats are intended to refine grain structure as you go through the forging process. Ensure you leave extra “meat” at the edge as “sacrificial” material that will be ground away after the heat treat process. Remember that you may use either a full or hidden tang blade for the JS test, but for safety sake, I recommend forging a full tang unless you feel supremely confident that you can make a hidden tang that will pass the bend test.
NORMALIZING: This is a critical step in a high performance blade. Once forging to shape is complete, heat the blade to just critical temp, and allow it to COMPLETELY cool in still air. This has the effect of relaxing all the internal stresses that have been built up during the forging process, and will eliminate 90% of warpage problems. Multiple cycles are of great benefit, and should be experimented with to achieve optimum results in your shop.
THERMAL CYCLING: This is basically an "insurance" step. This step CAN be used in conjunction with, OR in place of the Normalizing step. This step involves heating the forged blade to NOT MORE than 1350F, and then allowing it to cool to BELOW 900F. If necessary, turn your forge down (provides better control), and then DO NOT BE DISTRACTED BY ANYTHING. Bring the entire blade/tang to an even heat that is NOT MORE THAN 1350F. (visually this will be a VERY dull red, where the red color is just visually perceptible). If your judging by eye, place the blade in a shadowed area near your forge to better see the actual color. Once the blade/tang is evenly heated to the temp/color indicated, place it on a rack of some type to cool. DO NOT lay it on it's side on the anvil or any other heat sink! Allow the blade to cool to at least 900F (there will be no color in the blade, but it will still be too hot to handle with welding gloves...allowing it to cool more is not an issue...not allowing it to cool enough is!) Repeat for a total of three times, then proceed to the annealing step. Proper thermal cycling will "repair" any grain enlargement that occurred during the forging step, and will ensure a fine, tight grain structure for the remaining operations.
ANNEALING: Once the blade has completely cooled, it is time to anneal. Bring the blade to a little past non-magnetic, and place in a slow cooling media. I recommend vermiculite. Sand is not a good insulator, and ashes draw moisture, which can result in hard spots (something you certainly DO NOT want at this point). I usually do my annealing in the evening, and allow the blade to cool overnight. Routinely it takes a test blade sized piece of steel 6-10 hours to fully cool in vermiculite. This step reduces grain size within the steel, and may be accomplished multiple times for added benefit. Like normalizing, multiple annealing cycles are of added benefit to both 5160 and 52100.
ROUGH GRINDING: This is simply where the blade is profiled and refined prior to the heat treatment. Distal tapers can be refined or added at this point. Ensure you leave enough extra material in the edge so as not to overheat it during hardening. I recommend about the thickness of a nickel. I choose to call this extra material “sacrificial”, as it acts like a protective shroud to what will be the working edge of the blade. After rough grinding is complete, ensure you go over the entire blade with at least 120 grit to eliminate the possibility of stress risers that may be caused by large scratches that are left from the course grit belts.
HARDENING: Keep in mind that we are talking about 5160 steel. I recommend edge quenching ONLY on a blade that will be used for something as important as the ABS JS test. I DO NOT endorse fully hardening a blade, and "soft back" drawing... because most people do not do it correctly, and very often it will end with the blade breaking during the bending portion of the performance test.
If you don’t already have one, make a “limiter plate” for your quench tank. This is nothing more than a ¼” to 3/8” thick piece of aluminum that is choked full of 3/8” holes. At each corner drill and tap a ¼” X 20 hole and use carriage bolts with the heads facing the bottom of the quench tank, and screwed into the holes at each corner of the plate. This will allow you to raise and lower the quench depth to fit any blade. Once the limiter plate is set to the proper depth (about 1/3 of the blades width), pre-heat the quenching oil (if you are using vet grade mineral oil, pre-heat the oil to approx. 130F. Be careful here; DO NOT quench in mineral oil if the oil is 180F or higher. At this temp the oil will not cool the steel fast enough to achieve full hardness and your blade will not pass the chopping portion of the ABS JS test.
If you are using a fast quench oil such as Parks 50, I recommend using it at room temp (50-70F).
Using approx. a #3 welding tip on an Oxy/Acty torch, and with a SOFT flame (a flame that does not roar, but has a very mild hiss.), start heating the ricasso area near the edge, and as soon as it starts to turn color, then work the blade back and forth until it is just past non-magnetic (I recommend going slightly past non-magnetic because the actual critical temp for most steels is approx 150F beyond non-magnetic).. you also must consider that there will be a certain amount of heat lost between removing the torch and getting the blade INTO the quench oil. This heating step may also be performed with a salt tank, or even the forge, but be fore warned....the chances for mistakes are much greater than if you have practiced with the torch....remember, we are seeking to create a blade to pass a given set of circumstances (the ABS performance tests), not an everyday user. Although I am an advocate of differential heat treating, and believe with experience and correct application, it creates an outstanding "user", it is certianly not the only way to create a blade.....but in my expereince it is the best way IF you're goal is to pass the ABS Performance tests.
Once the entire edge is an even heat, quench by placing the tip into the oil first, for a count of 7, and then rock the rest of edge into the oil for another count of 7. Continue rocking the blade back and forth in this manner until all the “fumes” have ceased. At this point slide the blade off the limiter plate, and allow it to cool COMPLETELY in the oil, to room temp. Repeat the process twice more for a triple quench.
Once the final quench/cool cycle is complete, grind off the scale with a 120 or 220 grit, and get ready to temper.
TEMPERING: Pre-heat your oven to 350F. If you are using a kitchen oven, don’t trust the dial! I also strongly suggest an oven thermometer (I use two just to make sure). Let the oven cycle for 20-30 min to achieve a level, even heat, and place the blade on the middle rack for AT LEAST TWO HOURS. Allow the blade to cool to room temp between tempering cycles, and repeat for a total of three tempering cycles.
FINAL GRINDING: This is where the rubber meets the road. To this point you have set everything else up for a fine convex grind, and a nice flowing, distal taper. This can be a slow process since your dealing with a blade that has been heat-treated, and you should be grinding bare handed. If the blade gets too hot to hold, then it is too hot period! I start with a fresh 50-grit belt, cleaning up the tapers and then remove excess material from the flats of the blade. I usually will flat grind with the 50 and then a 120 which will reduce weight and thin down the area just above the edge. Once I hit 220 I go to a convex grind. I do this through a modification I made to the grinder platen, where there is approx. a 2” area that is slack just below the platen, and above the lower contact wheel. Your goal at this point should be for the edge to be very close to "sharp" by the time you finish with a 400-grit belt, as well as having the spine rounded and all sharp corners removed. (sharp corners can, and often do cause blades to fail in the 90-degree bend test).
Just to make things easier when hand sanding, I often go over the blade with a 600 grit belt to get as many 400 grit scratches out as possible. Once you have completed with the belt grinder, go to the bench and hand sand out all the scratches with 400 grit paper. (I prefer the final finish to be lengthwise...the scratch pattern following the blade's length) Even though the ABS rules state that the blade need not be highly finished, DO IT! I can usually tell when a potential JS walks into my shop to test, as to whether or not they will pass, based on the outward appearance of their test blade. This is an outward and immediate indication of how careful an individual has been with the overall process… Especially if I have not met with the person before. To date, my initial predictions have not been proven wrong.
HANDLES/GUARDS/BOLSTERS: The test blade is not required to be a highly finished piece, and therefore guard and bolster are not necessary. A couple of tips that will help with the bending test are..…….
1. Choose some type of micarta or phenolic for the handle slabs. Both of these materials are very tough, and will lend support to the tang area during the bending phase of the test.
2. DO NOT use large handle bolts that force you to drill large holes in the tang! This will only serve to weaken the tang, and could cost you dearly during the test. I suggest holding the handle material in place with epoxy, and at the maximum, a couple of 1/8” pins. Maybe even just a couple of 1/8” brass pins that are piened to hold the handles.
NOTE: The thing that will get you through the test easily is paying close attention to details! Superior heat treatment, proper distal tapers to distribute the bending stresses, a fine convex grind, and rounding all sharp corners. I personally like to see a test blade that has been etched lightly in ferric chloride to reveal the temper line and the grain structure. This is also key, in that if the blade is not finished to the point where a light etch will show the temper line and grain structure, I believe it is not finished enough for the test.
Many may insist on using another type of steel, and that is fine. As long as enough experimentation/experience has taken place to ensure all the desired characteristics are there. In the past, individuals have passed the JS test with other types of steel such as O-1 or 1095. However, these individuals had taken the time and effort to work out the "kinks". More aspiring JS applicants have passed the test with 5160 than with any other steel..................that should speak volumes!
This article is intended as a general guide to creating a blade that will pass the ABS JS tests, and is in no way a guarantee of success. Much depends on the individual Bladesmith's understanding of proper blade design in relation to function, and applying the concentration necessary throughout the ENTIRE process of creating a test blade. These are proven methods from 25+ years of bladesmithing experience, and should be of much value to anyone interested in achieving their ABS Journeyman Smith rating.
Copyright 2019: "The Montana Bladesmith"