Posts: 649 Location: Italy
Tue 29 Sep, 2009 1:55 pm
Hello,
make a sword blade tempered already be a great job. :eek:
Work often special steels, also 5160.
These steels, steels with memory we call them for their ability to return to original form.
If I think of our heat treatment before, during and after work ... I am amazed by your passion. :)
Bruno, if you want 5160 or a steel better, ask. ;)
Ciao
Mau
Posts: 649 Location: Italy
Tue 29 Sep, 2009 4:18 pm
Re: Leafsprings heat treating ?
Ozsváth Árpád-István wrote: |
Hello all!
I try to make a sword from leafspring. Overheating can be avoided, but that's not my primary concern. Leaf springs are already heat-treated, ideal for absorbing shocks, but I dont't think they will have good edge retention. Is there a method for quenching just a few millimeters of the edge, leaving the rest unmodified (like hacksaw blades)?
Arpad |
Ozsváth,
Leaf springs are already heat-treated, they are Through hardening and not Surface hardening. This means that the hardness have few difference in HRC between Through and surface.
Not like hacksaw blades that you say.
Ciao
Maurizio
Posts: 919
Thu 01 Oct, 2009 12:49 pm
Maurizio D'Angelo wrote: |
Hello,
make a sword blade tempered already be a great job. :eek:
Work often special steels, also 5160.
These steels, steels with memory we call them for their ability to return to original form.
If I think of our heat treatment before, during and after work ... I am amazed by your passion. :)
Bruno, if you want 5160 or a steel better, ask. ;)
Ciao
Mau |
Ok I will take it as an offer when i need steel ... ciao
Posts: 131 Location: Romania
Sun 04 Oct, 2009 1:31 am
Leafsprings heat treating ?
Maurizio, there's some misunderstanding. Leafspring is a already hardened to do what it was intended to do: absorbing shocks and not for good edge retention. Therefore the leafspring is too soft to hold a good edge. If you try to quench the whole blade to make a harder edge (50-55 HRC) it will become brittle as glass and will break apart at first impact. Somehow you can temper it, you must heat up to 200-300 centigrades, keeping it for hours than let it cool very slowly. It's difficult to achieve that for the edge it's much thinner and will heat up faster and therefore will loose it's hardness, not to mention bending and warping, problems that are hard to correct. That's for the "don't try this at home" section. Only a few experts can do proper heat treating.
If you look at hacksaw blades, you will notice that they are hardened only at a narrow, few millimeters section behind the teeth. To achieve this they use special induction heaters. Only that portion of the blade passes close to the the induction coil and are heated. That's differential hardening and would be ideal for leaf-spring swords resulting in a hard edge and leaving the original temper for the rest of the blade unmodified.
If you can only access such hardware...
Take a look at this:
http://www.youtube.com/watch?v=j5_zSrMN3s4
Posts: 649 Location: Italy
Sun 04 Oct, 2009 1:51 pm
Ozsváth Árpád-István wrote: |
.
If you look at hacksaw blades, you will notice that they are hardened only at a narrow, few millimeters section behind the teeth. To achieve this they use special induction heaters. Only that portion of the blade passes close to the the induction coil and are heated. That's differential hardening and would be ideal for leaf-spring swords resulting in a hard edge and leaving the original temper for the rest of the blade unmodified.
If you can only access such hardware...
|
If I understand correctly.
The differential hardening is very different from induction hardening.
The two things are not equal.
A differential hardening is better for swords, I never read about hardening swords with induction hardening.
For example, the features of the natural state of 5160 is inadequate as resistance.
Become appropriate if the temper at least 43-45 HRC. But much depends on the type of use
I agree that it is best to harden the edges while keeping the remaining material less hard.
This is achieved with a differential hardening.
With an induction hardening, as hacksaw blades, the hard part is only a few mm from the edge, the rest of the blade remains unprocessed. This is not good in terms of resistance.
Well, now you blade (Leafspring)
You say: "Leafspring is a already hardened to do what it was intended to do: absorbing shocks and not for good edge retention. Therefore the leafspring is too soft to hold a good edge. If you try to quench the whole blade to make a harder edge (50-55 HRC) it will become brittle as glass and will break apart at first impact."
This is not true. You make all blade to 50 HRC, trust me, it does not break like glass. If you know that this is 5160, and of course if the treatment is correct.
Ciao
Maurizio
Posts: 131 Location: Romania
Mon 05 Oct, 2009 11:27 pm
Leafsprings heat treating ?
Maurizio D'Angelo wrote: |
Well, now you blade (Leafspring)
You say: "Leafspring is a already hardened to do what it was intended to do: absorbing shocks and not for good edge retention. Therefore the leafspring is too soft to hold a good edge. If you try to quench the whole blade to make a harder edge (50-55 HRC) it will become brittle as glass and will break apart at first impact."
This is not true. You make all blade to 50 HRC, trust me, it does not break like glass. If you know that this is 5160, and of course if the treatment is correct.
|
You're right Maurizio! If you know the material and you have the required equipment and knowledge, you can make a better heat treatment.
The problem is that I don't know the exact type of steel. I was lucky to find a stack of straight leaf springs used fo cabine suspension on some heavy machinery. In the communist era they used other standards called STAS instead of ISO so it's difficult to tell what kind of steel they used for making leaf springs. This is essential for heat treating as different materials require a slightly different treating process.
I'm quite satisfied with it's properties. It's strong and flexible. It can sustain my weight (cca. 85 kg) and comes back to it's original shape without any deformations. It's not much you can improve on that, therefore I have to find a method for hardening just the cutting edge, those few millimeters - after all that's the part you must keep sharp.
Posts: 411 Location: Madison, WI
Tue 06 Oct, 2009 12:38 am
Your best bet might be to make 3 or 4 small trial blades from the steel and seeing if you can get a proper edge without any heat treat. If you don't, then heat treat each of your trial pieces a different way and destructively test them to see which process worked the best.
Apply what you learned to making your sword, and you should be on the right track.
Posts: 649 Location: Italy
Wed 07 Oct, 2009 9:46 am
Michael Pikula wrote: |
Your best bet might be to make 3 or 4 small trial blades from the steel and seeing if you can get a proper edge without any heat treat. If you don't, then heat treat each of your trial pieces a different way and destructively test them to see which process worked the best.
Apply what you learned to making your sword, and you should be on the right track. |
I think that is a good idea. Michael's suggestion is a non destructive. :)
Good luck Ozsváth.
Ciao
Maurizio
Posts: 131 Location: Romania
Mon 08 Mar, 2010 11:17 pm
I left my sword to rest sometime, I was busy with my family and my bayonet collection. But now as spring is coming I feel the urge to chop down some hostile bushes from horseback :D
You convinced me about heat treating. I find my blade material too soft, unable to keep a good edge. Now I have a question about tempering, my concern is to have a decent, but not too brittle blade, because I want a functional sword, not just a wall-hanger. It has to take a lot of abuse without breaking.
Blacksmiths are used to heat-treat knives, they temper blades to a pale yellow or so, but swordblades build up a lot of stress therefore they must be a little softer. Can you tell me the right tempering color (or temperature). Well I still don't know the exact type of steel, it's just "somekinda' leafspring"...
Posts: 313
Tue 09 Mar, 2010 12:04 am
A LOT depends on the steel. Carbon steel should be tempered to purple or blue. Alloy steels may need to go beyound that. And once the steel becomes gray (after lighter blue) it is virtually impossible to tell the temperature by the color.
I would advise to quench your steel in oil (maybe even hot oil, try with a scrap piece before you attempt to quench a sword). The slower your steel cools down, the less likely it is to warp or crack.
Then test it with a file. If the file does not bite, the quench is successful (unless you overquenched the steel). If the file bites easily, then you've failed. If it does not bite but leaves some marks then you've got a slack quench. Test in several places, not just one. Remember that you cut with the tip of the blade, so the base of the blade may be much softer, it will not cause any problems.
If you partially failed (for example got a slack quench or there are softer spots on the half of the blade that is closer to the tang) I would not recommend to quench the blade again. If you've failed once, there are very few chances you will succeed next time with the same blade. It's more psychology than physics. Reattempt quenching only if you ended up with a totally soft blade. But before the second attempt thoroughly anneal the blade (well, you'd better do it before the first attempt too). And do not make the second attempt on the same day.
When you are sure that the blade was quenched successfully, you should temper it ASAP. In case of unknown steel I would recommend to temper to lighter blue (comes after concentrated blue which in turn comes after purple). Softer is always better than broken, you know. Well, if your steel gets a decent hardness when quenched in hot oil, you may be sure that you got some alloy steel. If it quenches in cold oil but does not quench in hot, then most likely you've got plain carbon steel. In the latter case you may decide to temper to purple color to get a harder blade (I would not recommend it though). If the blade was slack quenched then you may decide to temper to yellow or brown color because the blade is not that hard already. For carbon steels it is enough to heat the steel to the decided color and then let it cool down about 5 times (the more the better). But if you can hold it at required temperature for an hour or two, do so. And then repeat. Alloy steels take A LOT more time to temper (and leaf springs are usually made of alloy steels). Ideally you should keep it at the required temperature for 2 hours, let it cool down and then repeat. I never heat treated blades made from alloy steels myself so I cannot tell whether it will be enough to just heat it and then cool down 5 times like I did with carbon steel. Depends on particular steel, I guess.
I would advise to temper base of the blade and tang a little bit more then the rest of the blade to make them softer but more resilient. And of course the end of the tang should be annealed.
And finally, as my experience has shown, the blade should not be that hard to hold the edge against some bushes. So do not get discouraged if you don't get the ideal 50-52 HRC. 40 HRC will also make a good sword. You may need to sharpen it more often, but consider it as a good practice. Believe me, this experience will be very handy when you finally get a good valuable sword with hard blade.
Posts: 131 Location: Romania
Tue 09 Mar, 2010 2:03 am
Well, thanks a lot I will keep that in mind, I should contact someone who works in a heat-treatment facility, because I have no experience in doing that and absolute no equipment. I still have some work on the blade and I'll try to bring it to the final stage before heat treating and the final sharpening.
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