differential tempered EUROPEAN swords
Jul 9, 2008 7:17:13 GMT
Post by Deleted on Jul 9, 2008 7:17:13 GMT
Is there anyone that produces differential tempered EUROPEAN swords ?
( slightly off topic )
And, Would filling the fuller of a sword with a similar clay as used in heat treating Japanese swords work as a technique to increase this differential tempering effect ? Maybe leaving the edges at 52 to 54 R.C. and with the center of the blade in the 40 to 45 R.C. (Just guessing here as to the numbers.)
Any idea if European swordsmiths ever used this technique ? Or did they use different ways to get a similar effect. I have seen a tool that resembled a tong that perhaps was used to apply heat to the center of the blade to retemper it. This would be done by heating the ends of the "tong" hot enough that touching the fuller of the blade would turn it blue quickly. You need to do this on both sides simultaneously, then need to cool immediately {water}, or you risk softening the edges too.
Doing something like this gives a hard edge, and a softer body. Today, Tinker does something like this to "differentially temper" his blades, and he comes up with an edge of 58 to 60rc, and a body of 46 to 48 rc. This also gives you a very different product than traditional differential hardening, the Japanese way.
Even without the antique tools, differential tempering makes sense. We know that many of the older antiques exhibit varying hardness', and we know that many of them exhibit a springiness to them. Pearlite isn't overly springy, its tough, tends to bend {take a set} relatively easy compared to the same crossection martensite.....
We have texts from the 16th C about the tempering of steel and those show us that there was a developed understanding of the effects of heat, cooling rate and degrees of temper of steel. Although there was no concept of carbon content.
Steel used varied as well. From the rather crude to material of very high quality.
When heat treating simple carbon steel, and especially in a very fine grain structure (as you would want in a sword blade) the ability to harden gets pretty low. That means you will have to cool the material very quickly to get any martencite at all. The martensite you get will also not go very deep. How deep depends on carbon content, grain structure, quenching medium, shape of cross section of the blade, mass of the blade and amount of heat to remove.
Knowing this, it becomes pretty obvious how meaningless it becomes to speak about specific effects of "medieval" methods and apply these in a very general way. There are simply too many variations to take into account.
What we can see is that a simple "monosteel" blade of diamond cross section will just as a result of its cross section get a variation in hardness from the edge to the spine. The core will also show a mixture of pearlite and bainite in a thick blade. It is like a skin of varying thickness with martensitic structure (hardened) around an oval core with a less hard structure. In a thinner blade the base might have this mixture of "unhardened" material in the core, while the outer section towards the point gets hardened all the way through.
Please not this need not be the result of lamination of iron core, steel surface: a monosteel blade of simple carbon steel will show this variation of structure trough out its length and thickness.
This is a result of varying cooling rates of different parts of the blade.
You do not have to play with differential tempering to get these effects of varying hardness. They could well have done that, but it seems the most applied method up till the 15th C was to temper on the remaining heat: an interrupted quench. This can give good results but takes high skill to do well. It does not lend itself well for differential tempering, though. I am not saying it was not done.
If you also play with the heating of the blade so that the edges get a higher heat than the core, you will also get interesting result without having to resort to clay coating or any other exotic method.
In a text from 1780, Sven Rinman, a swedish metallurgist, writes that a recommended way to give heat treat to cut and thrust swords was that an experienced master should heat the blade so that the edges glowed orange and the midrib was more dull. This was only the result of skillful handling and experience, he wrote...
I found this on another forum:
lets look at the quality of the weapon juxtaposed to its intended use.
Japanese steel: Crucible method in conjunction with cementation processes.
Made with Smelted ore that needed to be refined by forge folding and or carborizing/decarborizing to make a somewhat even distribution of carbon for the cutting edge. Very often had a soft (low carbon)inner core.
Inherent beauty as a result of the forging process.
Heat treat method : Differential hardening due to clay coating
Results:
Hard edge, soft back.
Very soft inner core (not always)
Excellent to Good shock absorption,
Medium to poor ductility. Takes and "sets" a bend.
The body is relatively stiff due to the tapering as well as the pearlitic body.
Uses:
Used against occasional armor
(they made more obtuse angles edges for this or dulled them for the intended use)
and soft flesh.
(Not much to say there)
Manufacture to use comparison: Excellent
______________________________________________________
Viking steel: Process speculative (crucible and or cementation).
Made with Smelted ore that needed to be refined by forging to make a somewhat even distribution of carbon for the cutting edge?? Very often had a soft (low carbon)inner core. Folded and sometimes twisted on itself. Hard outer edge, wrapped around the core all together different from the Japanese style of wrap.
Inherent beauty as a result of the forging process.
Heat treat method : Differential hardening due to the low-medium carbon core. NO clay needed.
Results:
Hard edge, soft to spring tempered body core.
Excellent shock absorption,
Excellent ductility. springs back from a bend.
The body is stiff and flexible due to the tapering as well as the spring tempered martensitic body.
Uses:
Used against occasional armor
(Obtuse angles, edges unknown) Hell of a war blade
and soft flesh.
(Like butter)
Manufacture to use comparison: Excellent..
_____________________________________________________
European steel: Cementation product up to mid seventeen hundreds.
Made with carbonized iron that needed to be refined by forging.
There were various methods used to carbonize the steel and then to fold it. Processes known as Blister and shear respectively. It is unknown when the blister and shear processes were actually founded only when they were revived.
To make a somewhat even distribution of carbon for the cutting edge. Blister steel was folded to homogenize the carbon distribution.
Inherent beauty as a result of the forging and Fullering (bevels and concave surfaces)process.
Heat treat method : A through hardened piece, that was then drawn back to a spring temper. I have not heard of *ANY* Differential hardening processes that were done on European steel.** WRONG! Differential hardened blades were quite common from 1200 and up.
Results:
Medium, spring tempered body AND edge. Good edge retention
Excellent shock absorption,
Excellent ductility. springs back from a bend.
The body is stiff and flexible due to the tapering and fullering as well as the spring tempered martensitic body.
Uses:
Used against occasional armor and soft flesh.
Manufacture to use comparison: Excellent
for armor
and flesh ..
_____________________________________________
WOOTZ steel: crucible
Smelted product that needed no refinement by forging. Forging was done at low temperatures to maintain a dendritic structure. (No further comment)
Very HARD. VERY (with a capital V) flexible
Inherent beauty as a result of the Smelting and (very important term in this case) forging process. The original Damascus steel. Indian in origin and then named after the trade route city it was commonly found in.
Heat treat method : Not hardened in any typical sense. The body is not all converted to martensite. (No further comment)
Results:
Hard edge, hard body, spring tempered back.
Excellent shock absorption,
Excellent ductility. Springs back.
The body is relatively stiff due to the tapering as well as the structure of the body.
Uses:
Used against occasional armor. "Known to cut European swords in half"**... another myth ?
and soft flesh.
the ONLY swords that will cut through silk when dropped over it ** is that a myth ?
Manufacture to use comparison: Undeniably Excellent.
______________________________________________
** my personal comments
( slightly off topic )
And, Would filling the fuller of a sword with a similar clay as used in heat treating Japanese swords work as a technique to increase this differential tempering effect ? Maybe leaving the edges at 52 to 54 R.C. and with the center of the blade in the 40 to 45 R.C. (Just guessing here as to the numbers.)
Any idea if European swordsmiths ever used this technique ? Or did they use different ways to get a similar effect. I have seen a tool that resembled a tong that perhaps was used to apply heat to the center of the blade to retemper it. This would be done by heating the ends of the "tong" hot enough that touching the fuller of the blade would turn it blue quickly. You need to do this on both sides simultaneously, then need to cool immediately {water}, or you risk softening the edges too.
Doing something like this gives a hard edge, and a softer body. Today, Tinker does something like this to "differentially temper" his blades, and he comes up with an edge of 58 to 60rc, and a body of 46 to 48 rc. This also gives you a very different product than traditional differential hardening, the Japanese way.
Even without the antique tools, differential tempering makes sense. We know that many of the older antiques exhibit varying hardness', and we know that many of them exhibit a springiness to them. Pearlite isn't overly springy, its tough, tends to bend {take a set} relatively easy compared to the same crossection martensite.....
We have texts from the 16th C about the tempering of steel and those show us that there was a developed understanding of the effects of heat, cooling rate and degrees of temper of steel. Although there was no concept of carbon content.
Steel used varied as well. From the rather crude to material of very high quality.
When heat treating simple carbon steel, and especially in a very fine grain structure (as you would want in a sword blade) the ability to harden gets pretty low. That means you will have to cool the material very quickly to get any martencite at all. The martensite you get will also not go very deep. How deep depends on carbon content, grain structure, quenching medium, shape of cross section of the blade, mass of the blade and amount of heat to remove.
Knowing this, it becomes pretty obvious how meaningless it becomes to speak about specific effects of "medieval" methods and apply these in a very general way. There are simply too many variations to take into account.
What we can see is that a simple "monosteel" blade of diamond cross section will just as a result of its cross section get a variation in hardness from the edge to the spine. The core will also show a mixture of pearlite and bainite in a thick blade. It is like a skin of varying thickness with martensitic structure (hardened) around an oval core with a less hard structure. In a thinner blade the base might have this mixture of "unhardened" material in the core, while the outer section towards the point gets hardened all the way through.
Please not this need not be the result of lamination of iron core, steel surface: a monosteel blade of simple carbon steel will show this variation of structure trough out its length and thickness.
This is a result of varying cooling rates of different parts of the blade.
You do not have to play with differential tempering to get these effects of varying hardness. They could well have done that, but it seems the most applied method up till the 15th C was to temper on the remaining heat: an interrupted quench. This can give good results but takes high skill to do well. It does not lend itself well for differential tempering, though. I am not saying it was not done.
If you also play with the heating of the blade so that the edges get a higher heat than the core, you will also get interesting result without having to resort to clay coating or any other exotic method.
In a text from 1780, Sven Rinman, a swedish metallurgist, writes that a recommended way to give heat treat to cut and thrust swords was that an experienced master should heat the blade so that the edges glowed orange and the midrib was more dull. This was only the result of skillful handling and experience, he wrote...
I found this on another forum:
lets look at the quality of the weapon juxtaposed to its intended use.
Japanese steel: Crucible method in conjunction with cementation processes.
Made with Smelted ore that needed to be refined by forge folding and or carborizing/decarborizing to make a somewhat even distribution of carbon for the cutting edge. Very often had a soft (low carbon)inner core.
Inherent beauty as a result of the forging process.
Heat treat method : Differential hardening due to clay coating
Results:
Hard edge, soft back.
Very soft inner core (not always)
Excellent to Good shock absorption,
Medium to poor ductility. Takes and "sets" a bend.
The body is relatively stiff due to the tapering as well as the pearlitic body.
Uses:
Used against occasional armor
(they made more obtuse angles edges for this or dulled them for the intended use)
and soft flesh.
(Not much to say there)
Manufacture to use comparison: Excellent
______________________________________________________
Viking steel: Process speculative (crucible and or cementation).
Made with Smelted ore that needed to be refined by forging to make a somewhat even distribution of carbon for the cutting edge?? Very often had a soft (low carbon)inner core. Folded and sometimes twisted on itself. Hard outer edge, wrapped around the core all together different from the Japanese style of wrap.
Inherent beauty as a result of the forging process.
Heat treat method : Differential hardening due to the low-medium carbon core. NO clay needed.
Results:
Hard edge, soft to spring tempered body core.
Excellent shock absorption,
Excellent ductility. springs back from a bend.
The body is stiff and flexible due to the tapering as well as the spring tempered martensitic body.
Uses:
Used against occasional armor
(Obtuse angles, edges unknown) Hell of a war blade
and soft flesh.
(Like butter)
Manufacture to use comparison: Excellent..
_____________________________________________________
European steel: Cementation product up to mid seventeen hundreds.
Made with carbonized iron that needed to be refined by forging.
There were various methods used to carbonize the steel and then to fold it. Processes known as Blister and shear respectively. It is unknown when the blister and shear processes were actually founded only when they were revived.
To make a somewhat even distribution of carbon for the cutting edge. Blister steel was folded to homogenize the carbon distribution.
Inherent beauty as a result of the forging and Fullering (bevels and concave surfaces)process.
Heat treat method : A through hardened piece, that was then drawn back to a spring temper. I have not heard of *ANY* Differential hardening processes that were done on European steel.** WRONG! Differential hardened blades were quite common from 1200 and up.
Results:
Medium, spring tempered body AND edge. Good edge retention
Excellent shock absorption,
Excellent ductility. springs back from a bend.
The body is stiff and flexible due to the tapering and fullering as well as the spring tempered martensitic body.
Uses:
Used against occasional armor and soft flesh.
Manufacture to use comparison: Excellent
for armor
and flesh ..
_____________________________________________
WOOTZ steel: crucible
Smelted product that needed no refinement by forging. Forging was done at low temperatures to maintain a dendritic structure. (No further comment)
Very HARD. VERY (with a capital V) flexible
Inherent beauty as a result of the Smelting and (very important term in this case) forging process. The original Damascus steel. Indian in origin and then named after the trade route city it was commonly found in.
Heat treat method : Not hardened in any typical sense. The body is not all converted to martensite. (No further comment)
Results:
Hard edge, hard body, spring tempered back.
Excellent shock absorption,
Excellent ductility. Springs back.
The body is relatively stiff due to the tapering as well as the structure of the body.
Uses:
Used against occasional armor. "Known to cut European swords in half"**... another myth ?
and soft flesh.
the ONLY swords that will cut through silk when dropped over it ** is that a myth ?
Manufacture to use comparison: Undeniably Excellent.
______________________________________________
** my personal comments