Epic fail O-1 Quench crack

J.Marsillo

J.Marsillo

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Nov 8, 2000
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I might be over reacting because I have been working on this dagger for over a year and a half.The picture pretty much says all...I hit it with a file and it doesnt appear to go too deep,but it looks real bad.It does have audible continuity if that means anything. If this is a crack the only thing I can think of is it started in a machine mark from the belt grinder...I normally use 10xx or W-2 and these kind of things dont happen during heat treat.

I quenched at 1550 in parks 50....Theres the problem:foot: parks 50 is too fast for O-1 isnt it? Back to the grinder tomorrow...
 

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Oh that is epic, and ironic...

"how many times do we have to tell you, get some proper quench oil! Using Parks 50, bah. You need to get yourself some good used motor oil!" :D

Canola oil would be just as bad or worse.

While thin parts in O1 is a good application for a slower oil, I think you'd still want the vapor jacket control and even cooling of a formulated oil on a nice dagger like that rather than something like motor oil.

Did you interrupt the quench or did you leave it in to finish?
 
I have never seen a crack like that.... could the barstock have had a lamination problem(for lack of a better term) from the mill?... hmmmmm
 
Magnussen said:
I have never seen a crack like that.... could the barstock have had a lamination problem(for lack of a better term) from the mill?... hmmmmm
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Thats what I was thinking. I've seen the same thing in rolled bridge girders. Admittedly that's on a whole different scale, but still.
 
J.Marsillo said:
...I quenched at 1550 in parks 50...Theres the problem:foot: parks 50 is too fast for O-1 isnt it? ...
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Not really... well yes it is faster than necessary for O1 and not the best choice but simple sections like a knife should not be too scary. No, I can see precisely what the real problem was and I am surprised nobody else picked up on it...
J.Marsillo said:
...I quenched at 1550 in parks 50...Theres the problem:foot: parks 50 is too fast for O-1 isnt it? ...
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if that means 1550 degrees Fahrenheit before quenching you WAY overheated O1 and I would entirely expect even more dramatic cracking in a faster oil. You over-austenitized, grew some grain and this resulted to far too much strain in the quenching operation. Don’t feel bad you are not alone, for some reason I see quite a few folks posting temps that are way off for O-1, where are these temps specs coming from?

Heat O1 no hotter than 1500F, but between 1475F and 1500F is better. The greater your carbon content, the closer to 1475F you want to stay, this alloy is rather touchy about overheating. Just about any medium speed oil will work for you, at 1475F #50 may work but can be a little riskier than a lightly slower oil.
 
1550F.... hmm.... didn't even register. I know that too. I feel like I just muffed a gravy question on an exam... jeeze:o

Still, though.... I have never seen a crack like that... mostly like this...

Heattreatpic-1.jpg
 
I have had 1095 flint strikers crack like that in a water quench. They cracked with the grain direction in 1/4" square steel. I switched to a brine quench, and no more cracks, so I would guess in my case the problem was uneven cooling. I have never cracked 01, even in thin blades, but I heat and soak at 1485° and quench in AAA.
 
:o A touch too hot huh??? Damnit all....This kills me,I have been taking my time with everything only to blow it in the home stretch.The only reason I used O-1 was the size of the stock worked out for what I had.Another one on the wall of shame :grumpy:
 
LRB said:
I have had 1095 flint strikers crack like that in a water quench. They cracked with the grain direction in 1/4" square steel. I switched to a brine quench, and no more cracks, so I would guess in my case the problem was uneven cooling. I have never cracked 01, even in thin blades, but I heat and soak at 1485° and quench in AAA.
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Longitudinal cracks just like that are common an a couple alloys that I have helped people out with these days. In recently made 1095 it is very common due to segregation stringers running right up the center of the piece, any quench the slightest too fast will result in cracking if the temper is jumped on immediately. Every single one of my 1095 metallography samples that are not tempered developed fracturing right down the stringer.

I have cracked plenty of O1 but only in sections thicker than 3/8" and particularly when the heat source was not thorough and even. Differentials in expansion from center to outer skin makes cracking in 3/4" O1 almost a given. But in blade cross sections you need to overheat it to get the same, allowing predominantly O1 to air cool from welding temps is catastrophic if you are using Ketos (the O1 chemistry sold by Crucible), but the chemistry offered by Carpenter suffers the problem to a much lesser degree, if at all. Just one more reason to know exactly what steel you have in order to avoid these heartaches.
 
J.Marsillo said:
:o A touch too hot huh??? Damnit all....This kills me,I have been taking my time with everything only to blow it in the home stretch.The only reason I used O-1 was the size of the stock worked out for what I had.Another one on the wall of shame :grumpy:
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Don't sweat it Joe...... just start another one :rolleyes:

fwiw, I think we all have a "wall of shame" ;) I know I do :grumpy: :)

:thumbup:
 
Not a wall of shame, but a wall of lessons learned, and reminders to not repeat those mistakes.
 
Magnussen said:
Some of us have a dedicated "ROOM of shame"....:D


If you aren't failing... you aren't learning.



Rick
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aye, The Wall of Learning, as I like to call it. The garage is full of cracked whitewater oars, a 7 year old bottle of Newcastle I chugged and certain other whitewater related articles that serve as reminders for... incidents. Just don't do it twice?
 
Magnussen said:
1550F.... hmm.... didn't even register. I know that too. I feel like I just muffed a gravy question on an exam... jeeze:o

Still, though.... I have never seen a crack like that... mostly like this...

Heattreatpic-1.jpg
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Looks like jaws, Dunna dunna dunnadunnadunna CRACK!!!!:eek:
 
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