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James M. jones

San Mia San sad.... why did the steel split?

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My first post here , please be gentle and help us lol....Been smithing for many years , made several blades including San Mia and patern welds but experience a new flaw that has me baffled.... working with an apprentice, had him forge welding wrought iron jacket onto O1.... the welding after preparing, went great all clean welds gas forge , power hammer , normalized , and a crack down the center of the o1 length wise , right down the center , splitting or tearing the o1 but not the weld ....round one .....round two flux weld , rinse repeatedly , the crack seemed to disappear when polished, several rounds of normalizing , a quench and temper 430f ,,,, and sone of a birch, that crack came back , just had him grind it back and it seems to go clear through, but the edge seems fine ..... and ..... ????? Something at a loss , been forging o1 a few years with pretty good success, is the iron pulling it apart? ..thanks for any help ..sincerely cute but clueless......image.jpgimage.jpg

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I'm not following the story line in conjunction with the photos. The first pic is of the edge, yes? If so, it definitely looks like a weld flaw between the jacket and the core. The second pic is a little too fuzzy to be certain, but it looks like there are two flaws. One is right by the thumb and looks like a sheared weld, the other is a dark line through the jacket to the core.

InkedInkedimage_opt.jpg

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8 minutes ago, Joshua States said:

I'm not following the story line in conjunction with the photos. The first pic is of the edge, yes? If so, it definitely looks like a weld flaw between the jacket and the core. The second pic is a little too fuzzy to be certain, but it looks like there are two flaws. One is right by the thumb and looks like a sheared weld, the other is a dark line through the jacket to the core.

InkedInkedimage_opt.jpg

Sorry for the poor photos , it,s not a failed weld , it is the O1 split down it,s center, like a peanut butter sandwich separated down the middle with butter stuck to both sides.... like perhaps the shrinking of the wrought on the outside stretched the inside while at that black heat. ....hope that clear things up. 

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OK. So my next question is how hot are you forging? O-1 likes to be forged HOT. Like 1800*F and above hot. 

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92A0B2E3-F094-482D-B80B-4C792FA0B575.jpegThe circled section is simply a grind ding. Here’s a better photo polished and quick etch , the o1 is the dark center wrought is white , a crack right down the middle .... 

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4 minutes ago, Joël Mercier said:

Is it cold rolled or hot rolled O1?

There is such a thing as cold rolled O-1?

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4 minutes ago, James M. jones said:

the o1 is the dark center wrought is white , a crack right down the middle .... 

If I had to guess, I would say that is a stress fracture from forging too cold.

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2 minutes ago, Joël Mercier said:

Is it cold rolled or hot rolled O1?

Drill rod forged my start blanks were about 3/8 thick 3 pc x 3/4 , x 3.... , tried to forge it hot like at weld temps , had an apprentice working on it , he did most all , so it,s possibly a cause , had to stop him from hitting it cold a few times... do others here use a o1 with wrought for San mai? Would like to rule out the bad combination theory if possible.

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I have not used these two for San Mai or any forge welding ops. I do not think it's an incompatibility issue though. If it were, it would probably display at the weld lines. O-1 doesn't move as fast under the hammer as WI does, so I would expect the problem would appear in the welds before causing the O-1 to split. 

I use a lot of O-1 drill rod and forge it down for blades. It's my favorite steel. I know some folks use O-1 in Damascus, but I avoid any chromium alloy steels for mine. I know that in theory, it shouldn't matter unless you try welding it to itself, but that's theory. You should get the same coloration and effect using 1095 instead of O-1 and have a much easier welding operation.

Edited by Joshua States

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Now this is something I have some exerience with, as in, I have experienced it.  I make tomahawks and axes, which require what is basically a san mai to do the edge.  When using mild steel and 1095, it always worked with a water quench until one day it was cold.  That quench split the 1095 right down the middle.  It's the same reason katana blades curve, the hard steel contracts before the not-hard part, forcing first a downward curve, then an upward curve.  It's that uoward part that then splits the hardened steel core in san mai and axes.  Use a slower quench, and never put it down during the forging process lest it air harden a bit on a cold surface.

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Another case cracked by Sir Longmire!

:o

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I asked because I've seen some cases of steel splitting in two during the quench. The failures were due to cold rolling issue.

But at this point, I had no idea the steel was from a round and O1 wasn't sold cold rolled. The last batch of steel I bought was 26c3 and it's been cold rolled.

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15 hours ago, Joël Mercier said:

O1 wasn't sold cold rolled.

I don’t know if it is or isn’t. I just don’t remember ever seeing it.

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i remember this being a problem for others with wrought iron and very high carbon or deep hardening steels combined switch to a lower say 1085 or so i think fixes it

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1 hour ago, dragoncutlery said:

i remember this being a problem for others with wrought iron and very high carbon or deep hardening steels combined switch to a lower say 1085 or so i think fixes it

Interesting, I,ve done plenty of San mai, but with a water harden core of thin stock, not much stock reduction, wanted to try more reduction of the mass for a more developed weld line . , so perhaps the deep hardening aspect of o1 does contribute...? Probably try the same thing with o1 again with a higher forging temp just to test, but also a simple steel for comparison.

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A higher forging temp is not what you need.  You just need to let it cool more slowly during normalizations and use a very slow oil for quenching.  And yes, the deep-hardening aspect does not help.  It is doable, people do it with Hitachi Blue Paper #2 all the time, but it does take more care in handling than a more shallow-hardening steel.  

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On 9/22/2019 at 10:46 AM, Alan Longmire said:

A higher forging temp is not what you need.  You just need to let it cool more slowly during normalizations and use a very slow oil for quenching.  And yes, the deep-hardening aspect does not help.  It is doable, people do it with Hitachi Blue Paper #2 all the time, but it does take more care in handling than a more shallow-hardening steel.  

...... check and thanks, so next go , I will plan to forge hot , normalize ....and leave it in the forge to cool down , Don,t have. Aheat treat furnace yet. ., so ....what oil would be slow , we currently are in transmission fluid , heated with an iron rod to laser said three hundred something ,,,.... vertical plunge with no agitation.    , also what about air hardening the o1 , ? 

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I can maybe add some food for thought to what Alan is talking about(the Hc steel deforming in quench blowing the weld apart) 

In Japanese Blacksmithing its a common technique to intentionally bend the kitchen knives over to the side of the Hc steel
that way during the quench they will natural straighten themselves out (what little deformation remains is addressed after tempering by bending the knives in a wooden block with slots sawed into and using a small hand held steel tapping tool to hammer on the low carbon steel.)
maybe that could help reduce the bending and the stress on the weld during quench.

and there's the cold forging Japanese technique to compress only the low carbon steel before the quench that also reduces deformation?(haven't read much on this yet so...hmm)

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Quenching in warm or hot canola oil would be better than transmission fluid, around 120 degrees is what most people go for if they use canola.

hot oil is a huge fire risk, if your oil is hot enough and you spill it during a quench the hot blade will ignite the oil and you might have several gallons of burning oil pour through your shop depending on your quench tank size.

120 degrees, or uncomfortable to touch is hot enough, and might be "correct" for most knife making applications. 

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11 hours ago, James M. jones said:

...... check and thanks, so next go , I will plan to forge hot , normalize ....and leave it in the forge to cool down , Don,t have. Aheat treat furnace yet. ., so ....what oil would be slow , we currently are in transmission fluid , heated with an iron rod to laser said three hundred something ,,,.... vertical plunge with no agitation.    , also what about air hardening the o1 , ? 

Don't leave it in the forge, that way lies huge grain growth.  Just hold it in still air until it's black or put it down on a bed of ashes or something that's not a cold metal surface.  And Stephen is right. Warm canola is what you need, or even room temperature canola.  That ultra hot ATF is way too fast a quench for O1, not to mention the dangers of  deep-frying yourself.  The only time to quench in really hot oil is marquenching, and that uses a special oil at around 450 degrees to suspend the martensite finish point indefinitely.  Not really a home shop thing.

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Thanks again , will try the canola oil. And not soaking for the cool down , I do have an annelling bin , so... How many ways to mess something up are there anyways? Probably be giving it a go today .... 

14 hours ago, J.Leon_Szesny said:

I can maybe add some food for thought to what Alan is talking about(the Hc steel deforming in quench blowing the weld apart) 

In Japanese Blacksmithing its a common technique to intentionally bend the kitchen knives over to the side of the Hc steel
that way during the quench they will natural straighten themselves out (what little deformation remains is addressed after tempering by bending the knives in a wooden block with slots sawed into and using a small hand held steel tapping tool to hammer on the low carbon steel.)
maybe that could help reduce the bending and the stress on the weld during quench.

and there's the cold forging Japanese technique to compress only the low carbon steel before the quench that also reduces deformation?(haven't read much on this yet so...hmm)

Just to clarify, the o1 is split, not the weld , the blade San mai, came out straight, 

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First read this: http://www.cashenblades.com/steel/o1.html

then let me tell you something Kevin talked about at length at Ashokan 2015, which is how not to anneal O1.  You guessed it, the annealing bin is not necessarily the way to go.  If you can't guarantee the cooling from 1400 degrees F is slower than 40 degrees F per hour until you get below 1000 degrees F, you are creating lamellar pearlite.  This is only important if you want to file, drill holes, or otherwise machine the blade.  What happens is that when cooled a little too fast for spheroidizing the carbides, the carbides segregate out into sheets or lamellae.  These sheets of carbides are what chew the ends off drill bits.  I have a pile of little integral blades that suffer from this condition, once I have an oven I'll be doing the spheroidizing anneal so I can actually drill the pin holes in the buggers.  

If all you're doing is letting it cool off before hardening, no worries.  The lamellar structure will go away during the time at heat before quenching as the carbides go back into solution.  

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I should point out that the TTT diagram at the bottom of that linked page shows why you need a slow oil for O1.  You have just shy of 10 seconds to get the steel from 1500 to below 1000 degrees.  Anything faster than that is just stressing the steel unnecessarily. 

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