HT test last night, your opinions please.

Wade Jones

Wade Jones

Joined
Nov 1, 2009
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183
I decided to try out my HT setup last night. This was my first time using the forge and quench. I tyried to be as precise as I could using what I've read here.

Steel is Aldo's 1084, just as it comes.
Quench tank is 20mm ammo can filled with 5 gallons of McMaster's quench oil.
Oil heated with white fuel camp stove.
Forge is a Diamond Back duel burner.

Now for the pics. :)

Here's the quench tank and heater setup on my dirty garage floor.
f1.jpg


The forge on the Amazing Wade Jones Folding Work Bench.
f2.jpg


Heating the oil up. Took longer than I thought. Ambient oil temp was about 49°. Had no idea what temp this oil should be at. Just guessing based on other quenchants I've read about.
f3.jpg


Forge with ceramic probe. (I later found a flat ceramic shield in the box, but luckily the exposed wires managed to stay intact on this run :o).
f4.jpg


Forge at temp. I kept it there while I played with the regulator a bit. I was surprised at how fine the adjustments were. Soaked for about 1 minute I'd say.
f5.jpg


Quench was unspectacular.
{insert unspectacular image here}

Snap test. Ignore the yellow crud on the one piece. That's where it hit the drywall after breaking off.
f6.jpg


I have no idea what I'm looking at grain wise on this stuff. Was hoping someone could tell if it looks good or bad or what.
f7.jpg



Any comments, thoughts, opinions, criticisms, verbal harassment, etc., would be greatly appreciated. I want to iron this out before I do some blades in this thing.
 
Looks good to me, I test another piece or the same one you broke after tempering to see how it has changed. After tempering it should be alot tougher and less brittle, alot less brittle. It kind of fun to see this change and see how hard you have to beat it with a hammer to get it to break.

I am assuming you are going or have tempered???
 
To get a good idea of what the difference looks like, do the same procedure with a 5 minute soak at 1700F. The grain size should be much larger. Breaking a Nicholson file will give you the look of extremely fine grain.
Stacy
 
I'm no expert, but the grain looks pretty large to me. Do what Stacy said, and compare. What you're after is what the Nicholson grain looks like which reminds me of very fine velvet.
 
I guess we need to keep in mind the size of the image we're looking at. If that's Aldo's 1084, it should be 1/4" thick. The first picture is almost 4x magnification on my computer screen, and the second picture is over 8x magnification. I can see where holding it in hand, it may look pretty good, but it's hard to tell without a reference point in the photo.

Something to consider, Wade, is the placement of of your thermocouple. It looks like the ceramic sheath is getting heat, while the tip of the TC looks to be veiled by the piece of fire brick your steel is resting on. That may just be the perspective of the photo, but I'd say figure a way to put the TC at the level of the steel, exposed to the same condition as the steel. It's possible that your steel was hotter than the TC. Then again, maybe not with the direct flame from your design of forge. How long did you let the forge heat prior to putting in the steel? Make sure it's all the way heat soaked.

--nathan
 
I've never just heated up a bar and quenched it but have forged, normalized ht'd quenched and broken several just out of curiousity. They all had a grain structure with the consistency of milk, very smooth. Your grain structure looks very coarse.
 
Thanks guys. I have really no idea what it should look like so your comments are very helpful. I wish I had an old Nicholson file to bust... Anyone have a picture by chance?

So if this is too coarse, what does that tell me? i.e. what steps should I take to get the correct struture?
 
A normalizing cycle and thermal cycles will help. Bring the steel to 1600 and equalize, followed by a cool to black heat in still air. Then heat again, this time not as hot, to say 1500 and cool in air to black heat. Next time to say 1425, then to a dull red heat followed by a cool all the way to room air. This will set up a uniform grain structure and prepare the steel for hardening by the method you mentioned. You may try on the lower end of austentizing temps next time in case you're getting hot spots in your forge. Also, move the steel around in the forge to equalize the temperature during heating prior to quench.

Just some thoughts....

--nathan
 
I don't know, the grain looks a lot coarser than what I usually see. It could be smoother.

Try overheating it (1700F+) and see how much coarser it gets. Also try normalizing, then a 2-hour spherodizing anneal at 1200F and re-austenize at 1450F, see how much smoother it gets.
 
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Hey Wade, good to see another guy from Colorado.

Normalization cycles will reduce and refine the grain structure.

I recomend 3 step down normalization cycles. The first being above critical (1575-1600 F or so for this steel), the second at critical, and the third slightly below. Heat the blade as uniformly as possible, soak for a few minutes (5 should do it), then pull the blade and let it cool in still air (best to hang the blade or clamp the tang so that it cools uniformly and you arent setting it on a surface that could cause un-uniform cooling). I usually let it cool to room temperature between cycles to ensure complete transformation cycles occur.

And here's a tip for getting more even heat in a forge like that. Find yourself a section of pipe thats got a big enough inner diameter and length to fit blades in (don't use galvinized pipe though). Stick the pipe in the forge and let it get up to heat, and then stick the blades in the pipe to let them heat up. This indirect method of heating drastically cuts down on hot and cold spots and gives much more even heat along the length of the blade. You can also throw some combustibles in the pipe (bits of wood scraps, paper scraps, etc) to eat up some of the oxygen and cut down on decarb and oxidation a little.
 
Graham's suggestion of a muffle for heat treating is a great tip. Be sure to put your TC tip inside the muffle.

--nathan
 
I give away a lot of heavy walled stainless pipe for muffles. A few years ago I had a new smith making a big oven. He needed a piece of 3" schedule 80- pipe two feet long. He found one online for nearly $150. I took a 3' piece to a knife show and gave it to him.

Wade, Send me your shipping address, the length of your forge, and the size of your ports, and I'll send you a muffle.


BTW, a good trick is to lay the blade on the thermocouple tip. That way it reads the real blade temp, not the flame temp.

Stacy
 
From looking at the pick it appears your burners were hitting the steel and I'd bet the steel was 200f+ more than what your thermacouple read.The grain of that steel is quite large.Take up Stacy's offer and get a muffle.
 
The grain is too coarse for my liking. I can see light reflecting off individual grains, if the grain size is in the proper ASTM range (at least 8) you should not be able to resolve individual grains with the naked eye. The steel was most likely over heated. 1500F should not be too much for 1084, but your conditions may have different variables we are not aware of, dropping to 1475F couldn't hurt if your tools and process are giving that grain size at what is being read as 1500F. Either way don't sweat the grain size, it is one of the easiest things to fix with proper thermal treatments.
 
Awesome guys, much appreciated!
Stacy I will get you some measurements for the muffle, THANKS!

As far as the normalizing procedures Nathan, Graham and others mentioned... I was under the impression that such wasn't necessary for stock removal blades? I thought that was for forged work... am I wrong?

I've been annealing my steel before grinding on it, to make it easier for myself. But this test peice was cut off the bar, just as it comes, from Aldo. Which, as I understand it, is in a normalized state.
 
Most likely, if you're overheating the blade unintentionally, that is your biggest problem. A muffle in the forge can help that tremendously for future blades. As such, you may not need the extra normalizing/thermal cycles to refine grain in stock removal blades. However, normalizing after grinding can be a good idea to remove stresses set up in the steel by your machining processes.

--nathan
 
Wade Jones said:
Awesome guys, much appreciated!
Stacy I will get you some measurements for the muffle, THANKS!

As far as the normalizing procedures Nathan, Graham and others mentioned... I was under the impression that such wasn't necessary for stock removal blades? I thought that was for forged work... am I wrong?

I've been annealing my steel before grinding on it, to make it easier for myself. But this test peice was cut off the bar, just as it comes, from Aldo. Which, as I understand it, is in a normalized state.
Click to expand...

As I have figured before, some steel stock benefit greatly normalizing even if you will just harden it. As at the softest state (spheroidal annealed condition) you have bought from the supplier there is no guarantee that the grains and carbides are even you should refine the grain and carbide size and make them homogeneous. As a rule of thumb normalize before HT no matter what...
Emre
 
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