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Bryan W.





Joined: 27 Oct 2007

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PostPosted: Thu 21 Jan, 2010 12:48 pm    Post subject: Problems With Pattern Welded Blades?         Reply with quote

I was told recently that pattern welded blades are often unreliable and the "welds" often do not take and the blade breaks apart during forging and even at times during use.

This seems like it could certainly be a problem from a logical standpoint and I doubt anyone's taking their expensive pattern welded blade and whacking it against another sword but I never heard of it before from an industry professional. Has anyone else heard this before and if so is it true and have others run into this before where custom smiths will try to talk you out of it?
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P. Cha




PostPosted: Thu 21 Jan, 2010 12:56 pm    Post subject:         Reply with quote

If they are done poorly, yes the blade can de-laminate. All production laminated steel swords would get them in billets of pre-laminated steel and so the chances of those de-laminating is pretty small...although the REALLY low end stuff still can. If itīs a custom job...itīs a matter of trusting your smith Happy .
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Jeroen Zuiderwijk
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PostPosted: Thu 21 Jan, 2010 5:10 pm    Post subject:         Reply with quote

Weld flaws should be pretty visible as black lines if they extend to the surface. Generally welds are lengthwise in a blade or close to it. As the largest stresses are also lengthwise, possible disconnected billeds will act like wires in a cable: still very strong in tension, more flexible in bending, and with a possibility of buckling under compression. The buckling will only happen if the disconnected weld is much longer then the width of the billet (f.e. a disconnected edge from the core). If the disconnection is short, it doesn't signficantly weaken the blade. In that case it will only be an aesthetic flaw, rather then a structural. But if you see weld flaws of f.e. 10cm or longer, I'd think twice about trying to push the sword to it's structural limits.
Jeroen Zuiderwijk
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Ken Nelson




Location: central Wisconsin, USA
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PostPosted: Thu 21 Jan, 2010 7:26 pm    Post subject:         Reply with quote

Greetings

Yes, pattern welding (PW) can have flaws in it that can cause problems, but that is not necessarily the case. Unfortunately I have actually seen poor quality smiths try to convince a buyer that the several weld flaws that were visible in the blade were put there intentionally, and increased the strength of the blade. one quote I remember was "if those flaws weren't there the energy forged into the sword would cause it to split itself apart"

Unfortunately, the only way to be certain that there are no flaws in a PW blade is to have it inspected by x-ray or ultrasound. If you do not see any flaws on the surface you can be pretty sure that the smith welded properly. If you see one or two flaws on the surface, but they are small, you probably have a serviceable, although not top notch blade.

Talk to your smith, and ask questions, especially "why". If a smith can answer your questions accurately, readily, and can point you to places to check for yourself, or for more information, you can get a high level of trust in him or her knowing how to make a blade. if you start getting long drawn out answers, complicated and unusual procedures, or a smith saying "well, that is how it is because I say so..." keep your hand on your wallet and say your good byes. If you are curious about what a smith says, ask around before you make a commitment on a blade.

There are many steps to making a PW blade, each has a small window to hit to get the blade right, and a lot of opportunities to make a mistake. A smith you can trust will cut out and throw away bad sections as they are found, if not dump it and start over. Luckily though, with experience those problems dwindle.

I do not want to discourage you from PW blades. A well made forgeweld using compatible materials can be as strong as the parent materials. And PW blades have a beauty all their own.

"Live and learn, or you don't live long" L. Long
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Michael Pikula
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PostPosted: Thu 21 Jan, 2010 8:28 pm    Post subject: Re: Problems With Pattern Welded Blades?         Reply with quote

Bryan W. wrote:
I was told recently that pattern welded blades are often unreliable and the "welds" often do not take and the blade breaks apart during forging and even at times during use.

This seems like it could certainly be a problem from a logical standpoint and I doubt anyone's taking their expensive pattern welded blade and whacking it against another sword but I never heard of it before from an industry professional. Has anyone else heard this before and if so is it true and have others run into this before where custom smiths will try to talk you out of it?


A properly forged and heat treat pattern welded blade should be just as strong as a monosteel sword. There are ways that you can test the blade without fancy modern day equipment. Strike the edge into a steel plate with moderate force and there should be no chipping or rolling of the edge, flex the blade about 45 degrees in a quite area and listen very closely, if you don't hear anything as you are flexing or as it is returning then no welds have pulled themselves apart, and then check to see if the blade is still straight. If you want to throw in another test, slap the blade onto a flat surface such as a 2x4 very hard and the impact will create enough internal stress that if a weld was going to break it will most likely come apart. I always do these tests to my patten welded blades prior to etching since the acid will show any points that welds came apart.

Smiths need to be up front and honest with their customers. If there is a flaw, that doesn't make the sword void for sale, and even with minor flaws the sword should be able to hold up to any cutting that you would like to do with it. However it is the smiths responsibility to point the flaw out to you and if you are okay with the flaw being there, the smith should stand behind their work and replace the blade free of charge if it does ever fail. Getting every weld in a multi-bar construction is a very very difficult process, I have several shop beaters that I have found unsuitable for sale, but I have yet to have one fail on me when I take it to a tree and give it a good beating.
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Paul Hansen




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PostPosted: Fri 22 Jan, 2010 11:22 am    Post subject:         Reply with quote

Interestingly, the Hanwei Godfred became notorious for brittle fracture rather than delamination... WTF?!
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Jared Smith




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PostPosted: Fri 22 Jan, 2010 3:10 pm    Post subject: Re: Problems With Pattern Welded Blades?         Reply with quote

Michael Pikula wrote:

A properly forged and heat treat pattern welded blade should be just as strong as a monosteel sword.


This is true in my opinion. If we assume defect free completed works, the materials and mass ratios of different alloys used are still very important in that aspect though. Many pattern welders utilize lower than optimal blade strength (if used alone as a mono-steel) alloys for nickle and contrast layers. This can be reasonably well compensated for by using higher than "normal mono-steel blade" carbon content in the alternating materials to offset it. (The carbon diffuses rapidly enough that it should even out during the length process of pattern welding.) I prefer to match the amounts of alloys such that the final carbon content should be near 0.8% if no mistakes were made.

Recipes for billets given by many "knife" makers illustrates to me that some of them prize the cosmetic beauty of the finished blade more than optimum strength. I believe the majority of the more reputable ones could propose and deliver several different alloy approaches, which would have different strengths based upon your priorities; optimal strength, maximum contrast and beauty, or possibly other desires such as rust resistance as in the all stainless pattern welded knifes that some produce.

Absence of evidence is not necessarily evidence of absence!
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Liam O'Malley




Location: New JErsey
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PostPosted: Fri 22 Jan, 2010 7:38 pm    Post subject: Re: Problems With Pattern Welded Blades?         Reply with quote

Jared Smith wrote:
Michael Pikula wrote:

A properly forged and heat treat pattern welded blade should be just as strong as a monosteel sword.


This is true in my opinion. If we assume defect free completed works, the materials and mass ratios of different alloys used are still very important in that aspect though. Many pattern welders utilize lower than optimal blade strength (if used alone as a mono-steel) alloys for nickle and contrast layers. This can be reasonably well compensated for by using higher than "normal mono-steel blade" carbon content in the alternating materials to offset it. (The carbon diffuses rapidly enough that it should even out during the length process of pattern welding.) I prefer to match the amounts of alloys such that the final carbon content should be near 0.8% if no mistakes were made.

Recipes for billets given by many "knife" makers illustrates to me that some of them prize the cosmetic beauty of the finished blade more than optimum strength. I believe the majority of the more reputable ones could propose and deliver several different alloy approaches, which would have different strengths based upon your priorities; optimal strength, maximum contrast and beauty, or possibly other desires such as rust resistance as in the all stainless pattern welded knifes that some produce.


afaik most bladesmiths use 15n20 for contrast layers, high nickel, yes, but not soft. its extremely dense and wear resistant, while even when hardened considerably tougher than something like a high carbon ten series. Nickle also functions as a carbon migration barrier so if you're pairing it with 1095 the carbon content won't go down any more than in a mono steel blade worked for the same amount of time at the same amount of heat. i wholeheartedly agree that the alloys need to be appropriate to the blade though.

i guess i'm basically just saying problems in my experience tend to come down more to heat treating issues than welding flaws (within reason). and you'd have to ask jeroen or someone with more experience in archaomettalurgy than myself but i think most historic blades even on the cutting edge tended to have a lower carbon content than we tend to use now.
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Ken Nelson




Location: central Wisconsin, USA
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PostPosted: Fri 22 Jan, 2010 9:09 pm    Post subject:         Reply with quote

Quote:
Jared Smith wrote:
Michael Pikula wrote:

A properly forged and heat treat pattern welded blade should be just as strong as a monosteel sword.


This is true in my opinion. If we assume defect free completed works, the materials and mass ratios of different alloys used are still very important in that aspect though. Many pattern welders utilize lower than optimal blade strength (if used alone as a mono-steel) alloys for nickle and contrast layers


Agreed

I like a quip I heard from another bladesmith, it was along the lines of "well, if you wouldn't use that for a knife by itself, why would you use it for a welded blade?" Verhoeven has shown that the last weld alone can cause enough carbon migration to even out all of the layers in the steel (Metallurgy for those who forge steel, J. D. Verhoeven) 15n20 does not have enough nickel to slow carbon migration, but it has .75% itself, so if layered with 1075 there would be no migration, and with 1095 you would have a .85% average, assuming the same thicknesses and layers to begin with.

A slightly different problem to consider is hardening and tempering. To get a full strength blade, both (all) of the steels must have similar enough hardening and tempering ranges, as well as quench speeds. If you were to use 1075 and 15n20, good, they have similar characteristics, as do O1 and L6. a mix of 1075 and L6may not work well. There is a very small window to hit to get both steels to austinize. (1075 is 1450-1500deg F L6 is 1500-1550deg F) Below 1500 the L6 will not austinize and therefore remain pearlite, over 1500 and you will get grain growth in the 1075. Also, quenching can cause problems, the 1075 requires a fast quench like water, brine, or a really fast oil, the L6 works best with slower oils and salts. If you quench too slow, you can get pearlite showing up in the 1075. Having hard and soft layers in a blade will actually weaken it. You will get uneven stresses that may react badly with each other.

Quote:
i guess i'm basically just saying problems in my experience tend to come down more to heat treating issues than welding flaws (within reason). and you'd have to ask jeroen or someone with more experience in archaomettalurgy than myself but i think most historic blades even on the cutting edge tended to have a lower carbon content than we tend to use now.


In some places, not in others. If I recall there was a study done on the Ulfbehrt blades and some of the imposter blades. It seems that the genuine ones actually had a high carbon content, up to 1.2% When I first read the article, it shocked me that the blades were reported to have a carbon content of 1 1/2 times a modern tool steel. I had stopped and thought that the article might have meant something like 4140 or 5160, but after a few e-mails and questions, I was told that they really were over 1% carbon

"Live and learn, or you don't live long" L. Long
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Liam O'Malley




Location: New JErsey
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PostPosted: Fri 22 Jan, 2010 10:54 pm    Post subject:         Reply with quote

Ken Nelson wrote:

In some places, not in others. If I recall there was a study done on the Ulfbehrt blades and some of the imposter blades. It seems that the genuine ones actually had a high carbon content, up to 1.2% When I first read the article, it shocked me that the blades were reported to have a carbon content of 1 1/2 times a modern tool steel. I had stopped and thought that the article might have meant something like 4140 or 5160, but after a few e-mails and questions, I was told that they really were over 1% carbon


the disparity between steels is something i tend to obsess over a lot in my work, i pick steels with similar heat treat stats because of it. I knew the ulfbehrts were high carbon, but i never knew it was that insanely high, makes me wonder if there weren't some steel making techniques in that particular smithy that weren't supposed to exist in that time and place.
still, ulfbehrts were well known and of exceptional quality, so that may not be the norm, and I also tend to pay more attention to the earlier end of the migration period, especially seaxes. still pretty cool though lol.
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Jeroen Zuiderwijk
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PostPosted: Sat 23 Jan, 2010 4:06 am    Post subject: Re: Problems With Pattern Welded Blades?         Reply with quote

Liam O'Malley wrote:
i guess i'm basically just saying problems in my experience tend to come down more to heat treating issues than welding flaws (within reason). and you'd have to ask jeroen or someone with more experience in archaomettalurgy than myself but i think most historic blades even on the cutting edge tended to have a lower carbon content than we tend to use now.

Patternwelded swords have been found that are entirely made of virtually pure iron (except for slag inclusions). There's even pattenwelded swords that have better quality steel in the core then on the edge. Of course those are the lower end examples.

Regarding the strength of patternwelded vs monosteel swords, that is of course only true when you consider modern high quality steels. If you compare that with ancient swords, where frequently combinations of poor quality iron and steel were used in patternwelding, those are naturally a lot weaker. Also to be kept in mind though is that frequently not the whole swords were hardened, often just the edges. The steels they had to work with were shallowhardening, so thicker parts wouldn't harden on these blades. In that case the non-hardened parts are still pretty soft and prone to bending even if the carbon contents is high (though carbon does increase the strength compared to no carbon, but not nearly as much as if it were hardened properly). So if you have a very accurately made reproduction of a patternwelded sword, there's a pretty good chance that if you bend it over your knee, it will not spring back all the way.

Jeroen Zuiderwijk
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Maurizio D'Angelo




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PostPosted: Sat 23 Jan, 2010 5:26 am    Post subject:         Reply with quote

Blades P.W. have a beauty all their own. It 'hard to make them as well.
I believe that we must accept their limits, avoiding to want to compare with modern steel.
I think a blade in 6150 austempering (Bainitic structure) , can not be overcome by a PW.
They are simply different, each with characteristics that the other can not overcome.
Personally , I prefer a P.W.
I would trust a good blacksmith, no wait the characteristics of a good blade made of modern steel.

Ciao
Maurizio
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Jean Thibodeau




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PostPosted: Sat 23 Jan, 2010 10:53 pm    Post subject:         Reply with quote

Maurizio D'Angelo wrote:
Blades P.W. have a beauty all their own. It 'hard to make them as well.
I believe that we must accept their limits, avoiding to want to compare with modern steel.
I think a blade in 6150 austempering (Bainitic structure) , can not be overcome by a PW.
They are simply different, each with characteristics that the other can not overcome.
Personally , I prefer a P.W.
I would trust a good blacksmith, no wait the characteristics of a good blade made of modern steel.



Oh I think you mean with " no hesitation /reservations " instead of no wait probably a literal translation from the Italian. Wink
Big Grin


In French it would be " sans hesitations " which could be translate by a translating program as " no hesitation OR no wait " I imagine that in Italian there is a similar turn of phrase that would confuse the translation program to generate a too literal translation.

In other words you mean you wouldn't hesitate to trust a good blacksmith to make a good folded blade comparable in quality to a modern mono steel blade but that one should have different expectations as each has it's own unique qualities.

Assuming I'm correct I hoped this helps clarify the intent of your words.
Cool

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Maurizio D'Angelo




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PostPosted: Sun 24 Jan, 2010 1:22 pm    Post subject:         Reply with quote

Jean Thibodeau wrote:
Maurizio D'Angelo wrote:
Blades P.W. have a beauty all their own. It 'hard to make them as well.
I believe that we must accept their limits, avoiding to want to compare with modern steel.
I think a blade in 6150 austempering (Bainitic structure) , can not be overcome by a PW.
They are simply different, each with characteristics that the other can not overcome.
Personally , I prefer a P.W.
I would trust a good blacksmith, no wait the characteristics of a good blade made of modern steel.



Oh I think you mean with " no hesitation /reservations " instead of no wait probably a literal translation from the Italian. Wink
Big Grin


In French it would be " sans hesitations " which could be translate by a translating program as " no hesitation OR no wait " I imagine that in Italian there is a similar turn of phrase that would confuse the translation program to generate a too literal translation.

In other words you mean you wouldn't hesitate to trust a good blacksmith to make a good folded blade comparable in quality to a modern mono steel blade but that one should have different expectations as each has it's own unique qualities.

Assuming I'm correct I hoped this helps clarify the intent of your words.
Cool


You are a gentleman,
Thank you, my mentor. Is exactly as you say. Happy

Ciao
Maurizio
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