1084 heat treat help!

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Mar 17, 2018
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I have two bars of 1084 that I purchased from nj steel baron about 4 years ago. in the past week I made three knives out of one of the bars. Friend of mine came over today and brought his Rockwell tester. All three of the knives were not hard. Reading in the 30’s. I have an evenheat oven and I had heat treated all of them at 1475 for 10 minutes and quenched in canola oil heated to about 120. And tempered at 375 twice for two hours each. We proceeded to heat treat these knives 3 more times today. With varying soak times from 1 minute, 5 minutes and twenty minutes. We checked them as we were pulling them out to make sure they were non magnetic and to no avail we couldn’t get them to harden. Checked with a file and it would dig in. Also checked the rockwell tester with the calibrated test coupon that came with it and it was reading dead on.

Last thing we did was cut two test coupons, one from each bar and heat treated them. No luck.

Any help would be appreciated.

Thanks
Jason
 
The issue is the carbon is still spheroidized in aldo's 1084 and requires a little extra prep. let me find the thread where stacey gives the proper HT recipe
 
A torch isn't really a good way to HT, but it will work for 1084.

Here is a basic HT regimen forn 1084:
1084 HT:
refine grain and normalize -
heat to 1500F and air cool to black, then quench to cool
heat to 1350F ( just non-magnetic) and air cool to black, then quench to cool
heat to 1200F ( still magnetic) and air cool to black, quench to cool
Straighten any warp or twist

Austenitize-
heat to 1500F and hold long enough to allow the blade to be evenly heated
quench in a fast quenchant (or as fast as you have, canola will work for all but big blades)
Check for warp after holding in the quench oil for 5-8 seconds. Straighten immediately. Stop after about 20-30 seconds, as the blade will be too cool and may break.

Temper immediately at 450F for two hours, twice. Quench in water to cool between temper cycles.
( If there is any warp after the blade cools, it can usually be straightened while at tempering temperature. Let it heat for 30 minutes before any straightening.)
 
What volume of canola do you have? I would try a proper ht oil as well. I got 50/50 results with canola.
 
DO NOT!! I REPEAT, DO NOT use canola oil to quench any knife! that is your biggest problem right there.
Also like “scarysamcary“ said you need to set the steel up right first.
another problem could be a thick layer of decarb, so make sure you grind through that.
All that I have said you can see proof for yourself here https://knifesteelnerds.com/

I wish you good luck.

Regards Joseph.
 
Thanks Joseph

looks like I need different oil

i may just scrap the steel and go back to cpm154, I haven’t made any knives in about three years and was just trying to use what I had to get back in the swing
 
Ok, I'll give you my opinion on the situation from a metallurgical point of view:
1) Canola will be fast enough for 1084. It isn't a commercial quench oil, and won't last as long, but it will be sufficient to harden smaller blades made from eutectoid and hypoeutectoid steels. 1084 is the eutectoid steel. A gallon is OK for small blades. 120°F is a good temperature for it. Two gallons is probably better, but one should do it. When you can, get several gallons of Parks #50. It may last you a lifetime.

2) The steel structure is the problem here. Aldo had his steel spherodized at the mill and it is in a structure where the carbon is so tied up it doesn't get into solution at normal austenitization temperatures. You have to release the carbon before doing the HT.

Here is the method for HT for spherodized steel:
Heat the steel to 1650° and hold for 10 minutes. Cool to black/non-magnetic.
Heat the steel to 1550° and hold for 10 minutes. Cool to black/non-magnetic.
Heat the steel to 1450° and hold for 10 minutes. Cool to black/non-magnetic.
Heat the steel to 1475° and hold for 5 minutes. Quench, temper twice at 400°
 
If you must use canola oil 😒 at least do an interrupted water quench, the reason for this is that canola oil is a very slow oil when you first put the blade in, and THAT IS WHERE IT COUNTS (most people judge an oil’s speed by the nickel ball test, but that isn’t the whole story), so if you do a quick dunk into water and then finish in the oil you should get full hardness. Don’t worry about quenching any steel to fast (as long as it doesn’t warp really bad or crack) you are not losing toughness by quenching faster.
 
I disagree with the above, I find interrupted water quenches risky, especially for a new maker. They have use in attaining a hamon, but again, that is not a beginner skill.

Canola is a not a very slow oil. It is a 9-10second oil, just a tad below the 7 second oils we use for hypereutectoid steels. It is faster than AAA. For normal thickness small 1084 blades, it has a fast enough cooling rate to reach full hardness easily.
 
Not being argumentative, but Larrin's chart shows canola as right between the 10-12 and the 8-9 oils. That is where I placed it in my post.
Roughly 170°/sec vs Parks #50 at 215 °/sec. That is 80% of the speed of #50.
Canola is the fastest of the vegetable oils, IIRC.
The slow commercialoils are 15-22 second and have a cooling rate of around 90°/sec. Those oils are only 53% the speed of canola.

The one difference between canola and commercial quenchants is the initial drop during the first 200° after quench is slower, but the curve follows the same rates as commercial oils. Reaching the pearlite nose should not be a problem for normal thickness 1084 blades.

1643568838788.png

I'll let it go there, too.
Perhaps Larrin will pop in with any comments.
 
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Larrin's article shows that canola can harden 1084 in thin sections to some degree:
1-8-inch-oil-comparison.jpg

For a 1/4" thick cross section, canola is a poor choice:
1084-canola.jpg
 
if you're getting rc30 then it's not the quench medium that's the issue (unless you're quenching in a bucket of vermiculite). the wrong starting structure seems plausible, since it sounds like they were hot enough
 
Is no one going to start with the obvious and ask if any anti scale coating was used or if the decarb was removed before testing and if the blades were tested on a flat (both sides) decarb free, +120grit finish?

Also Canola oil is a horrible choice for 1084, there can be pearlite hiding in the microstructure.
 
The problem is that your not quenching in the blood of your enemies...

Nah I'm kidding, although I just wanted to chime in and say that this thread sounds kind of hypocritical? I mean that in the nicest way but what I am reading is people describing not to use canola for 1084/1080. Yes, I understand that canola is not meant to be a quench oil however a lot of us would probably tell a new maker to pick up some 1084 and canola to do a backyard HT and we would also probably tell them that they will get good results if done correctly. Notice I said good and not best. I believe that if you want the best results you have to use the best tools/methods to achieve them of course but I also don't agree with the fact that the 1084/canola quench method is getting shamed on if front of all the beginners out there reading this and trying to educate themselves on this topic. Like I said I fully understand that quenching in canola is not the best method for 1084, but it still does work.

Also, and correct me if I am wrong here but isn't Canola also recommended because of the fact that most people starting out use their household oven to temper and could run the risk of toxic fumes in the house as a result of quenching in something like Parks 50? Or am I just that dumb and you could solve this by washing the blade in dish soap and scrubbing the sh*t out of it and keep using parks in a home oven?

Like I said I mean this post in the nicest way possible and this is just my own little thoughts.
 
Yeah, not making any claims vs. commercial quenchants here, but I've hardened scores of 1084 blades in warm canola, and they come out north of 64Rc and perform well. Never had a problem w/ Aldo's 1084 either, but then one of the reasons I use 1084 is because doing a forge HT is so fast and easy, and no toxic fumes. (and I have a kiln)

I'm gonna go with Stacey on this one (as usual). Either give your material the full precision prep in the kiln, or shove it in a forge and quench it in your canola "when it's ready". I feel like if you're going to use a kiln, consider using a steel that demands it and gives you something extra in return.
 
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