Jump to content

Has anyone tried this combination of steels when forging long bladed swords?


Recommended Posts

I'm talking about swords with a blade length of thirty inches or more... you make 1075 carbon steel into an U shape and place 1045 carbon steel inside it.

 

I would be happy if anyone out there would try this and share the results because I'm not a swordsmith myself... just an enthusiast of good forged swords.

 

Thank you for hearing me out.

Edited by Mikael Andersson
Link to post
Share on other sites

For a single-edged sword that works fine. If done on a Japanese-style blade it's called kobuse construction. The question you should be asking is why do it with two high-carbon steels? 5160 is tougher than 1075, but that being true begs the question of just what you are trying to accomplish.

Link to post
Share on other sites

The reason it is not generally done is there's no advantage to it. A solid 5160 blade properly heat treated will perform better than a laminate and be easier to make since you're removing the risk of welding flaws and not tryng to kix a water-hadening alloy with an oil-hardening one. It's one thing to use historic methods with historic materials, and another one entirely to substitute modern homogenous alloys and expect similar results. If you want to do it simply to have a visible weld line it would work fine. If you are expecting a performance advantage you'd be disappointed.

Link to post
Share on other sites

Second on that. 5160 is not a really great steel for pattern-welding in any case. And using it for the core in the kobuse construction defeats the purpose- if you water-quench the combo your core will be as hard if not harder than the edge.

Link to post
Share on other sites

The reason it is not generally done is there's no advantage to it. A solid 5160 blade properly heat treated will perform better than a laminate and be easier to make since you're removing the risk of welding flaws and not tryng to kix a water-hadening alloy with an oil-hardening one. It's one thing to use historic methods with historic materials, and another one entirely to substitute modern homogenous alloys and expect similar results. If you want to do it simply to have a visible weld line it would work fine. If you are expecting a performance advantage you'd be disappointed.

 

Ah, I see but if we replace the 5160 steel with 1050 carbon steel... the same family of steels as for the edge (1075 carbon steel) but with a lower carbon content for the center of the sword.

Link to post
Share on other sites

Second on that. 5160 is not a really great steel for pattern-welding in any case. And using it for the core in the kobuse construction defeats the purpose- if you water-quench the combo your core will be as hard if not harder than the edge.

 

Yes, using 5160 steel was a bad idea... I replace that with 1050 carbon steel.

Edited by Mikael Andersson
Link to post
Share on other sites

If you are after a hard exterior/soft core blade all you really need is a shallow-hardening steel like 1075. Now, if you were smelting your own iron and had bars of differing carbon content, phosphorus content, and degree of refinement I'd be telling you to use the.soft stuff in the core and the high-p and high carbon on the outside in the form of pattern-welded bars.

 

With modern steels the only reason at all to do laminated construction is aesthetic. And that's a fine reason, don't get me wrong, but a laminated blade is not going give superior performance than a monosteel blade IF said monosteel is the proper alpo for the application and is properly heat-treated for the application.

Link to post
Share on other sites

If you are after a hard exterior/soft core blade all you really need is a shallow-hardening steel like 1075. Now, if you were smelting your own iron and had bars of differing carbon content, phosphorus content, and degree of refinement I'd be telling you to use the.soft stuff in the core and the high-p and high carbon on the outside in the form of pattern-welded bars.

 

With modern steels the only reason at all to do laminated construction is aesthetic. And that's a fine reason, don't get me wrong, but a laminated blade is not going give superior performance than a monosteel blade IF said monosteel is the proper alpo for the application and is properly heat-treated for the application.

 

Aha, I see and how much could a really good bladesmith raise the HRC degree on the edge of a sword forged from 1075 carbon steel?

Link to post
Share on other sites

Swords are not about HRC, they are about resilience. Think sharp leaf spring. With 1075 I wouldn't risk more than RC 55 or so at the most. 5160 and 6150 are far tougher at that hardness.

 

From the questions you ask I am guessing you have been mislead by the myth of Japanese swords. While they are an excellent example of how to use harder and softer steels together, a traditional one made from tamahagane is one of the most unforgiving blades ever made in terms of technique. One wrong angle of cut and you have a cracked edge or a broken sword. To try and apply this too-hard edge/ soft spine idea to a double edged longsword is asking for trouble if you try to spar with it. Each tradition developed the way it did for good reason.

 

Remember that during most of the age of European iron and steel swords a hardness of around RC 35 was considered excellent. Many Roman blades can't even be measured on the Rockwell C scale, you have to use the B scale or the Vickers scale. As Ric Furrer points out when the irrelevant issue of ultimate sword blade hardness comes up, "how hard is your skin on the Rockwell C scale? Humans are soft and squishy and can be punctured by a pointy bit of wood. All a sword needs to do to be good is not break."

Link to post
Share on other sites

It's worth noting that a.) the various constructions of Japanese swords had more to do with conservation of material than performance - seeing as only the edge was going to be hardened anyway, there was no point in using precious hardenable steel on the partsthat weren't going to get hardened, and b.) Japanese swords are round about twice the thickness of European swords, even before you account for fullers, so there was a lot more soft steel to back up the hardened edge. Performance wise, you really aren't going to beat properly hardened and tempered spring steel for a European style sword...

 

and remember that hardness is dictated by intended use - a good swordsmith could get c.65 rc on the edge of a 1075 sword (as could a bad one), but he wouldn't, because that would be silly...

Link to post
Share on other sites

Swords are not about HRC, they are about resilience. Think sharp leaf spring. With 1075 I wouldn't risk more than RC 55 or so at the most. 5160 and 6150 are far tougher at that hardness.

 

From the questions you ask I am guessing you have been mislead by the myth of Japanese swords. While they are an excellent example of how to use harder and softer steels together, a traditional one made from tamahagane is one of the most unforgiving blades ever made in terms of technique. One wrong angle of cut and you have a cracked edge or a broken sword. To try and apply this too-hard edge/ soft spine idea to a double edged longsword is asking for trouble if you try to spar with it. Each tradition developed the way it did for good reason.

 

Remember that during most of the age of European iron and steel swords a hardness of around RC 35 was considered excellent. Many Roman blades can't even be measured on the Rockwell C scale, you have to use the B scale or the Vickers scale. As Ric Furrer points out when the irrelevant issue of ultimate sword blade hardness comes up, "how hard is your skin on the Rockwell C scale? Humans are soft and squishy and can be punctured by a pointy bit of wood. All a sword needs to do to be good is not break."

 

I'm sorry, the small scraps of information that I have gathered comes from the internet as I have no real experience with this sort of thing.

Link to post
Share on other sites

It's worth noting that a.) the various constructions of Japanese swords had more to do with conservation of material than performance - seeing as only the edge was going to be hardened anyway, there was no point in using precious hardenable steel on the partsthat weren't going to get hardened, and b.) Japanese swords are round about twice the thickness of European swords, even before you account for fullers, so there was a lot more soft steel to back up the hardened edge. Performance wise, you really aren't going to beat properly hardened and tempered spring steel for a European style sword...

 

and remember that hardness is dictated by intended use - a good swordsmith could get c.65 rc on the edge of a 1075 sword (as could a bad one), but he wouldn't, because that would be silly...

 

Ah, I see.

Link to post
Share on other sites

it is ok. Information has to be accumulated over time.

All of us started out (or at least read early on) Jim Hrisoulas's books about bladesmithing and pattern welding. They are not a panacea, but it is as good a place to start as any. If you want to learn about Japanese stuff, Yoshindo Yoshihara and colleagues have good books. Forgive me if you have already read these.

 

After you get the information into your head somewhat, then you have to translate it to you hands, and that takes some time, too (I am still working on that part.). To your eyes, also. That seems to be a never-ending process of refinement.

 

enjoy. let us know what happens.

 

take care,

kc

Link to post
Share on other sites

and remember that hardness is dictated by intended use - a good swordsmith could get c.65 rc on the edge of a 1075 sword (as could a bad one), but he wouldn't, because that would be silly...

 

I agree with everything you say, except the edge of a katana is as-quenched (not tempered) -- typically 60 - 63 Rockwell. It's brittle as hell, but just saying :)

Link to post
Share on other sites

I agree with everything you say, except the edge of a katana is as-quenched (not tempered) -- typically 60 - 63 Rockwell. It's brittle as hell, but just saying :)

I'm pretty sure this is a myth, as a differentially hardened water quenched blade is under a tremendous amount of tension - enough to cause an untempered blade to crack from internal stresses alone - I've had the tip of a water quenched blade shoot off several inches from the body of the blade just lying on the bench. there is a word for the tempering process of japanese blades, though it escapes me at the moment, but it is acheived by passing the blade over the coals several times at least until water boils off the blade, and probably in most cases to 300 -350f, depending on depth of hardening... anyway, we are talking about european cross sections ie half the thickness, hardened on both edges. watch slow motion footage of cutting with a european sword and you'll see how dangerous untempered edges would be...

Link to post
Share on other sites

I'm pretty sure this is a myth, as a differentially hardened water quenched blade is under a tremendous amount of tension - enough to cause an untempered blade to crack from internal stresses alone

 

I assume you mean that the Japanese smiths eschewing tempering is a myth. I water quenched a clayed 1086M wakizashi under Howard's watchful eye, and it easily skated a brand new file.

We did temper it, but we're gaijin:)

 

But there are several peer-reviewed Japanese journal articles studying the microstructure of antique katana, and they really are 60 - 63 HRc. A good example is: Study of Microstructure on Cross Section of JAPANESE SWORD, M. Yaso, et al, Department of Materials Science, Shimane University, Metallurgical Research Laboratory, Hitachi Metals, Ltd. They section a 2nd generation 15th century Muramasa.

 

"Several researchers [14, 18] had investigated hardness of Japanese swords on surface plane and cross section up to now. They had reported the maximum hardness level in sharp edge was about 700-820 HV. "

 

700 - 820 Vickers is 59 - 63 Rockwell C. And indeed the 2nd gen Muramasa tested along the edge from 720 - 730 Vickers (60 - 61 Rockwell C).

 

 

there is a word for the tempering process of japanese blades, though it escapes me at the moment, but it is acheived by passing the blade over the coals several times at least until water boils off the blade, and probably in most cases to 300 -350f, depending on depth of hardening

 

In one of Yoshindo's videos, they show him quenching in water, and then plunging the blade back into the coals 2 or 3 times for a total of ~ 5 seconds to flash temper the blade. I'm not sure he wanted that part captured on film, but Howard or Ric (I can't remember which) told me he said that was something the toshi request to make it easier on the stones.

Edited by Robert George
Link to post
Share on other sites
  • 2 weeks later...

I was watching a video of a Japanese sword smith who was demonstrating the forging process from the very beginning. He began by selecting different pieces of the tamahagane they had made earlier, by how pliable vs how brittle the pieces were and separated them into two little stacks, the pliable for the core was on one side and the brittle pieces for the blade and outside body was on the other. Bear in mind that I know little to nothing about Japanese bladesmithing methods, but his selection process really interested me, although, after I thought about it, it seemed like common sense.

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...