O1 heat treat failure

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kesparate

Joined
Feb 13, 2003
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65
made a first attempt at heat treating a blade made from O1 today and seem to have met with complete failure. after quenching and temper the blade seems no harder than it was before.

here's what i did. i really hope someone can tell me which part was wrong....

went in to work on my day off where we have a small heat treat oven, and brought a supply of vegetable oil with me.

i cleaned the blade and put it in the cold oven. then fired it up.

over about 20-30 minutes the oven heated up to 1475 F. i didn't hold at the pre-heat temp as the temp was rising slowly enough i felt the blade was probably heating evenly.

when the oven reached 1450 i started a timer and held the temp between 1450 and 1500 for 15 minutes.

after fifteen minutes i grabbed the blade with some tongs and very quickly moved it to the oil. there was about 5 quarts of vegetable oil that was heated to a temp of about 100 f. when i grabbed it from the oven it was glowing fairly brightly and was light orange color.

i moved the blade up and down in the oil to ensure even cooling till the blade reached 130 f. i did take it out once to check the temp with a non contact thermometer and it was about 350 f. put it back in immediately.

the blade shifted in my tongs a bit and a portion of the handle was sticking out on the initial dunk which caused a bit of flame but only briefly before it was submerged too.

as soon as it reached 130 f i wrapped in in AL foil and transferred it to a preheated toaster oven at 400 f for 2 hours.

my research seems to suggest two possibilities:

one is that the thermocouple on oven is royally screwed up and i didn't hit critical temp. the oven is older than old so it's definitely possible the temp reads incorrectly but my research suggests that the steel had the appearance of being near critical temp so almost zero change in hardness seems odd.

two is that my steel was mislabeled. i don't know of any way to check this other than to try spark testing it. if it's a some other type of tool steel this may be difficult to determine.

any thoughts are welcome as i really like the blade.

thanks
 
How do you know it's still soft?
DO NOT heat your blade in a cold oven warming up. It will over heat your blade most assuredly and there is no need to expose it to that length of heating which will create a good amount of scale/decarb.
Decarb can be rather thick but if you can still file a good size notch in the blades edge then I you might have a problem.
If your blade was a orange color then your where plenty hot enough to harden most likely. Do you have a reasion to doubt the steel is O1. A quick test is use a cheep small drill bit and try and drill a hole in the tang. If it's hard you will make a mark in the decarb but won't drill a hole. This is less destructive then going at the edge with a file.
 
try double checking the thermocouple accuracy by using a magnet to make sure it doesnt stick to the metal when it is at temp.
 
It's definitely still soft. Did some filing and what not to check.

Is it possible I decarberized the steal to a point where it won't get hard by heating it in a cold oven?

It's not impossible it's the wrong steel as it was a discarded bar end from an old job. It is precision ground stock though and was still in the material wrapper which identified it as O1 with the correct dimensional specs.
If it's not O1 it would most likely be A2 or D2 as they were common in that shop. Would the material still be so soft if I followed this procedure with one of those steels?

Really appreciate the help. Thanks.
 
I'll bet if you grind it a bit you will hit hard steel. Under your conditions, you could not have decarbed the blade completely.

The only places I see that could be a problem are:
The 1450 temp is a tad low. It still should have hardened, though. If it ranged between 1450 and 1500, you would be fine. 1475 is my O-1 temp.
The oil should have been at 120-130F, but that doesn't make enough difference to not harden . You didn't say how big the knife was, but if it was not a large knife, 5 quarts should harden it.
The only part that was wrong was not cooling to room temp. The blade should be at 70-80F before tempering. Stopping at 130F and immediately putting in a 400F oven may have stopped the conversion to martensite early. It still would have been hard, but less than it should be.

I still suspect a thick decarb layer that needs to be ground off.
 
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Interesting point on the size of the blade. It's rather large at about 16" OAL and .281 thick. I'm now almost convinced I just screwed up the quench.
The manufactures recommendations said temper immediately at 130 but I kinda wonder if I didn't have sufficient oil and just got a bad reading with the non contact thermometer I was using to monitor the quench. If it was still three or four hundred degrees would I expect it to be soft through if I arrested the quench there?

It's definitely soft clean through. I remodeled the tip wth a file and drilled to center line with and uncoated high speed drill. Didn't complain at all and is still sharp.

Really grateful for the input. I really want to figure this out. It's bugging the crap out of me.
 
On a blade that large, I would use 2 gallons or more of canola oil.

The "temper immediately at 130F" is an industrial HT procedure for large scale processing and large objects. For blades, it is best to let it get to room temp, then temper immediately.

Re-do the HT with more oil and see if you get better results.
 
I would heat it to 1475F-1500F. If you heated to 1450F and the kiln is reading high, you would have missed the mark.

If it is any consolation, the first blade I ever quenched was O1. I thought I had this heat treat business down, man. Get it really hot and quench it really cold, right?.... LMAO. I heated a fully sharpened, clay coated(for hamon) O1 blade to yellow hot and quenched it in a bucket of ice and brine. The sound that came out of that bucket still haunts me...... sssscccreeeeeeEEEEEEEEEEEEEEEEELLLLLLLLL.... Pa-ping-ping-ping-twang ping... click... drop-clunk.

It did get hard, though. Now, I make sure to quench North - South to align the midichlorians.:cool::thumbup:
 
Rick Marchand said:
....The sound that came out of that bucket still haunts me...... sssscccreeeeeeEEEEEEEEEEEEEEEEELLLLLLLLL.... Pa-ping-ping-ping-twang ping... click... drop-clunk.

.......
Click to expand...

Hahaha.....I've done that (different circumstances though) and I have to say, that's a remarkably accurate description of that sound. :) And probably pretty darn close on the phonetic spelling too. :D
 
Rick Marchand said:
I would heat it to 1475F-1500F. If you heated to 1450F and the kiln is reading high, you would have missed the mark.

If it is any consolation, the first blade I ever quenched was O1. I thought I had this heat treat business down, man. Get it really hot and quench it really cold, right?.... LMAO. I heated a fully sharpened, clay coated(for hamon) O1 blade to yellow hot and quenched it in a bucket of ice and brine. The sound that came out of that bucket still haunts me...... sssscccreeeeeeEEEEEEEEEEEEEEEEELLLLLLLLL.... Pa-ping-ping-ping-twang ping... click... drop-clunk.

It did get hard, though. Now, I make sure to quench North - South to align the midichlorians.:cool::thumbup:
Click to expand...

That just made my day, we have all been there.
 
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