1084 heat treat help

Stang Bladeworks

Stang Bladeworks

Joined
Feb 19, 2018
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660
Hi
This is my first forum post. My questions pertain to heat treating 1084 properly. I have a hardness tester and an evenheat kiln. My problem is that my blades are not reaching full hardness. They test from 35 to 50 HRC depending where i test. My procedure is to put the blade in my kiln at 1475 and let it soak for 12 min. I have also tried putting it in at room temp and let it heat up but further research lead me to believe this was detrimental to the steel (lots of decarb) my edge will pass a file test once i get through the decarb. I have tried quenching in canola oil and vegtable oil (pretty sure they are the same thing) at 120 130 140 and 150f. They all pretty much yield the same result. When i quench in room temp water i get a proper 65 HRC across the entire blade. This leads me to believe the canola oil is not sufficient to fully harden the blade. My research indicates tons of claims that canola oil is all you need. Has anyone rockwell tested a blade from a canola quench? I have made complete knives using the oil and the edges seem ok. I have been using test samples that are ground flat with no burrs or sharp edges. I did try an actual blade in water and it warped alot. I dont think water is the answer. I plan to move to stainless but i would like to be able to do carbon steels as well. Any insight would be great thanks. I would like to thank Rob from knifemaker.ca for answering many of my questions on this topic already via email. I know the obvious answer is parks but I would rather invest the money in stainless equipment. Also vary hard to source in canada.
 
for a test i quenched a 1095 blade in oil, just the bade, for around 6 seconds. then quenched the handle in brine. the handle still hardened the blade did not. now i just drill all holes and leave a little more meat on the blade before heat treat, and do a double quench. going in water first then quickly to oil. you can google that im not sure it works as good on 1084. but when i started 1084 was what i used. i just water quenched then. i did get occasional warping but that can be taken out during tempering most of the time. if i have a warp i take and clamp it to a piece of straight 1/4 mild steel. heat treat for 1 hour twice and the warp is usually gone.
 
Some thoughts: how thick are your samples and how long are you leaving the blades in the oil? Are you agitating the oil (you can just move the blade up and down in quench for the same effect). If you remove the blade too soon, or don't agitate, it will overly auto-temper or not fully harden. Are you sure you're grinding off all the decarb layer? Also, what's the volume of the oil? Using too little oil can cause problems in hardening.

Also, if you've gone through the trouble to get a kiln and a rockwell tester, you might as well invest in some proper quench oil. Parks 50 works great on 1084.

EDIT: I also always austenitize 1084 at 1500 F. That may also help.
 
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You don’t need to soak 1084 either.

Use at least a gallon of oil and if you are using canola, heat it up first. I think 130-40 is the right temp... look at the stickies above on the main page. There is a HT section for good HT recipes.
 
1500/400. The commercial "medium fast oils" seem to have a "sweet spot" at around 150F.
 
I use canola oil to quench 1084. I had a knife tested by a forum memeber on his tester and it tested at 59hrc after 400 degree temper. Oil was heated to around 130 degrees. I used my forge to heat treat with.

Are you positive it is 1084?
 
These kind of threads show up often and the majority of times the problem is they havnt ground all the decarb away. Grind a little more and it will probably be hard
 
Thanks everyone for your input. I am using 9L of oil. My samples are only 2inch squares of 1/8 stock. I am pretty sure its 1084 because i purchased it from a reputable dealer. If anyone knows how to get parks into canada im all ears.i am agitating the sample in the oil during the quench. I have tried leaving it in the oil anywhere from 5 to 30 seconds. I am sure im getting past the decarb. I grind the samples down and test at different depths with no real changes. So far all i can conclude is that water is working and for me the oil is not.
 
At 1500/400 with my oven and Parks #50, I generally expect around 61Rc. That goes to show you that even "easy" steels can still benefit from precise temperature control and purpose made quenchant.
Justin Presson said:
I use canola oil to quench 1084. I had a knife tested by a forum memeber on his tester and it tested at 59hrc after 400 degree temper. Oil was heated to around 130 degrees. I used my forge to heat treat with.

Are you positive it is 1084?
Click to expand...
 
Spalted said:
These kind of threads show up often and the majority of times the problem is they havnt ground all the decarb away. Grind a little more and it will probably be hard
Click to expand...

I would guess there has been close to dozen guys with hardness testers that have come on here with steel that wouldn’t harden. Almost all of them weren’t grinding through the de-carb.

Logically speaking if you have a kiln, so, temp control, known steel, pre-heated canola and don’t lollygag heading to quench and use a longer than normal soak for 1084 on .125 material then de-carb is what I’d suspect as well. I wonder if the water quench is violent enough in the vapor jacket to lose some of the de-carb layer.

Have you broken your test samples in a vise post quench pre-temper? I bet they would snap like twigs. Try it.
 
I have tried to snap the samples. They do not snap when hammered in a vice. I am pretty sure im getting through the decarb. On the samples i have ground as much as 1/16 off and not seen any improvment in hardness. I would estimate my time from the kiln to the oil is about 2 seconds.looking online canola seems comparable to a medium speed quench while 1084 calls for a high speed 8ish seconds. I am pretty new to this and i could very well be wrong about all of it. I appreciate your reply
 
Try 1500f aus temp and 120 degree oil. 5 minutes at temp.

But if you're sure the steel is 1084, you're sure you're grinding through the decarb, your coupons don't snap pre-temper then I would be led to believe that your temperature control is not accurate.

My next step in trouble shooting this process would be to try multiple aus temperatures. Say 1490, 1500, and 1510. Do they harden? Do they get progressively harder? Do any reach rc 65?

Also, if you're doing 2x2x.125 coupons, how are you holding them? A big tong across the entire face is going to suck a lot of heat out of the coupon and interfere with the quench. I would drill a hole in the corner and put a wire loop through it, and use that to remove and quench.
 
I will give that a shot. I am hoping that a shorter time will reduce decarb. Im pretty sure my kiln is accurate because a water quench yields full hardness and it is non magnetic. If its off its not by much. I will try to snap the samples with a bit more force.
Thanks for your thoughts. Ill let everyone know how it went.
 
Stang Bladeworks said:
I will give that a shot. I am hoping that a shorter time will reduce decarb. Im pretty sure my kiln is accurate because a water quench yields full hardness and it is non magnetic. If its off its not by much. I will try to snap the samples with a bit more force.
Thanks for your thoughts. Ill let everyone know how it went.
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That water quench hardens is evidence that you're not quenching at the ideal aus temp. Non magnetic temperature is only 1420f. If your set temp of 1475 is actually giving you 1450 it would be non magnetic and I would expect it to behave as you describe via water/ oil quench.
 
Out of curiosity how old is the 1084 you have? It sounds stupid but I had a batch years ago where my forged blades were hardening but not my stock removal ones off the same bar. I don’t remember the exact issue but I believe it was something about having too much of a spheroid anneal or something. What I found was the blades needed to be cycled to about 1650 or higher, then normalized before the final hardening cycle. Like I said I can’t recall what the exact issue was, but that’s the general idea anyway. The blades were being done in a controlled salt pot and commercial quenchat a fellow maker had but I don’t recall what type. After cycling the blades up past 1650 plus a couple reducing heats, we did get them to harden properly. We were getting wildly varying hardnesses like you are. I believe our lowest was 38 and our highest tested spot was 55 and both readings were on the same sample piece within inches of each other.
 
My steel is about 8 months old i think. Thats interesting. Did you just it cool to room temp? If you could recall your exact procedure i would be very interested in trying it out.
Thanks
 
I tend to agree your steel may be highly spherozoid , heat to 1650 cool to black, heat to 1400 cool to black, heat to 1200 cool to black, then 1450 and quench in oil.
 
My steel will cool faster than my kiln will drop in temp. Does it matter if my steel gets to room temp between the steps?
 
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