Even wootz blades can break

tom hyle · 10th April 2005, 09:59 PM

I may not follow you, but many swords, especially some of the finest European swords, are designed to break in certain places, if they break, as the distal taper to a thin tip and a thick soft base; the tip takes up much stress in its easy flex, though it cutting it can be vibratory, and I find slashing or drawing the cut helps, while the (sometimes) soft thick base and soft usually thick tang are greatly absorbant of all other shock/stress. Also, some were desinged with a breaking point in the tang, above (behind, pommelward of) a rivet, so if the tang does break, it's still attached. The geometry, simple or crystaline of this I do not understand, BTW, as I am not the best heavy pommel balancer, neither, but I've read of it, and seen its results, many times.
Broken and damaged pieces are so educational to us, even if we don't repair them. Anyone got a snapped or chipped wootz blade to help us, maybe? Any modern smiths do toughness tests and find conditions/alloys/whatever where the steel is brittle?
Everything is harder and more brittle when cold. I have seen hard steel axes hammers and files chip or snap way "too" easily when very cold. They were all, AFAIK, modern steel, though say early to mid 20th. Folklore of Europe is "the Vikings" the North-Germans, and specifically the Swedes invented the sword that could take the cold by pattern-welding; note we just got an Eastern version of this lore, too(?): However, also, this seems to be the "viking spatha/swert" known to history and archaeology as mostly Frankish(? or Burgundian?) in numbers manufactured, if not in origin/design (hmmmmm; like navajas......)

Chris Evans · 11th April 2005, 02:11 AM

Hi,

The failure of swords in very cold climates is a fairly well known phenomena, indeed, as Tom so correctly points out, of all kinds of steel objects.

I have heard of Japanese swords so failing in the very cold winters of Hokaido. Essentially, it us due to the `Brittle transition temperature' (BTT).

The BTT is a temperature region at which the steel begins to lose all ductility and becomes exceedingly brittle. Alloying elements influence the BTT and it is determined by some kind of impact testing, usually by the Charpy or Izod tests, conducted over a range of temperatures. The temperature range at which the steel begins to exhibit brittle behaviour can thus be determined.

The steels from which old swords were made were a pretty mixed lot, especially when it came to alloying elements. As such, their behaviour at low temperatures was unpredictable.

Cheers
Chris

Gt Obach · 11th April 2005, 02:40 AM

hi
i guess my post may have been a little confusing... it is tough to find a source of error as to why the wootz may have been brittle in the northlands...
- retained austenite is just one possibility..
- grain growth during forging is another.. (if you forge at too high a temp for too long, it will encourage the crystal structure in steel to grow large-- this can make a blade brittle)
-stress in the steel..... if the steel is forged bellow non-magnetic, stress is put into the metal and this can make it brittle
- quenching a blade in an aggressive quenchant can also put lots of stress in the steel... it can lead to cracks.... this may not be apparent till later when the sword is used ....
-inclusions in the steel can also weaken it...

so as you can see..... there are several possibilities to having brittle steel ...... and lot's of it involve the smith and the way it was forged and heat treated

I have read the Persian steel book.....it is very interesting.....in there you will find a part that says some swords were quenched in hemp oil and fat.... or by other means.. there are many ways to heat treat wootz.... it all depends on the structures you want...

i've seen several persian swords with a quench line....where the sword etches darkly on the tempered martensite and very litely on the untempered side.....
-- i know this because this is exactly what happens with my blades... since i prefer to oil quench

I have made some swords of wootz.....and they all worked well.... preformed similarly to 5160 .... which is all I can tell
- I've chopped some of my bowies into 1/4 plate iron... (the are very large bowies.....since i like foot long blades).... and they handled the iron with good effect..... cutting a series of 1/8 inch gooves and no cracks or blade chips..

I haven't noticed any weakness due to pattern... ... sometimes as you hammer an ingot out.... you will get these large cracks... almost like delaminations ..... and my solution to this problem is to grind them out with a 6inch grinder......then forge it flat and keep going......
-however this give you a crazy pattern... since it has cut through some of the sheeting..... yet it will still make a dandy knife
- the prophets ladder can be made by grinding ladders in and forging flat.... and this pattern has shown no problem with cutting

I have a feeling that bulat is a little different....just by looking at the steel I feel that some of those blades are alloyed with different elements... their etch is different...
- how ever I don't think the bulat is weak or cracky..... i believe it can be if you don't roast your ingots before forging them out...
-I've had more problems with crackiness with those kinds of ingots..... and the pattern is much denser

I will try to email Visily and see if he finds his bulat is brittle in the cold..

Greg

I also agree that alloy could affect how it functions in cold

Jens Nordlunde · 11th April 2005, 03:01 PM

Hi Greg,

You wrote: ‘I have made some swords of wootz.....and they all worked well.... preformed similarly to 5160 .... which is all I can tell’.
What does 5160 mean?

When you have hammered an ingot out, and see there are cracks, can’t you melt it down again and start all over?

Jens

Gt Obach · 11th April 2005, 03:20 PM

Hi Jens
5160 is a carbon steel which has up to 1%Cr and .6 carbon.... therefore it is a medium carbon steel that deep hardens...... it works excellently for swords and other long blades...

Cracking... the cracks are not the same ones that you find on some ingots ..... these cracks form as you are forging ..... they resemble the delaminations you find occuring with pattern welded blades... .
- you could remelt the whole ingot......but this would cost alot of money.... 30lbs of propane and 40.00 for the crucible for the remelt....... it is better to grind out the crack.... and continue forging..... which has worked for me in the past.....
-- you can never tell which ingot will turn out to be grumpy and disobedient....lol

- in one experiment.....i left the delam and made it into a sword..... it worked fine....just have a big line in the middle of the blade.... it is unsightly

Greg

Jens Nordlunde · 11th April 2005, 03:59 PM

Hi Greg,

Have a look at the picture. Close to the grip the watering is nice, but then it starts to change - why?

Jens

tom hyle · 11th April 2005, 06:22 PM

BTW, let me just say that it has never been my impression that great strength, in general, was the reputed high magic of the wootz/bulat, but the magical cutting edge?

Jens Nordlunde · 11th April 2005, 06:28 PM

Hi Tom,

I am not sure that I agree to this, but I will have to come back to it later, as I don't have any more time at the moment.

Jens

11th April 2005, 02:40 AM	#3
Gt Obach Member Join Date: Mar 2005 Posts: 116	hi i guess my post may have been a little confusing... it is tough to find a source of error as to why the wootz may have been brittle in the northlands... - retained austenite is just one possibility.. - grain growth during forging is another.. (if you forge at too high a temp for too long, it will encourage the crystal structure in steel to grow large-- this can make a blade brittle) -stress in the steel..... if the steel is forged bellow non-magnetic, stress is put into the metal and this can make it brittle - quenching a blade in an aggressive quenchant can also put lots of stress in the steel... it can lead to cracks.... this may not be apparent till later when the sword is used .... -inclusions in the steel can also weaken it... so as you can see..... there are several possibilities to having brittle steel ...... and lot's of it involve the smith and the way it was forged and heat treated I have read the Persian steel book.....it is very interesting.....in there you will find a part that says some swords were quenched in hemp oil and fat.... or by other means.. there are many ways to heat treat wootz.... it all depends on the structures you want... i've seen several persian swords with a quench line....where the sword etches darkly on the tempered martensite and very litely on the untempered side..... -- i know this because this is exactly what happens with my blades... since i prefer to oil quench I have made some swords of wootz.....and they all worked well.... preformed similarly to 5160 .... which is all I can tell - I've chopped some of my bowies into 1/4 plate iron... (the are very large bowies.....since i like foot long blades).... and they handled the iron with good effect..... cutting a series of 1/8 inch gooves and no cracks or blade chips.. I haven't noticed any weakness due to pattern... ... sometimes as you hammer an ingot out.... you will get these large cracks... almost like delaminations ..... and my solution to this problem is to grind them out with a 6inch grinder......then forge it flat and keep going...... -however this give you a crazy pattern... since it has cut through some of the sheeting..... yet it will still make a dandy knife - the prophets ladder can be made by grinding ladders in and forging flat.... and this pattern has shown no problem with cutting I have a feeling that bulat is a little different....just by looking at the steel I feel that some of those blades are alloyed with different elements... their etch is different... - how ever I don't think the bulat is weak or cracky..... i believe it can be if you don't roast your ingots before forging them out... -I've had more problems with crackiness with those kinds of ingots..... and the pattern is much denser I will try to email Visily and see if he finds his bulat is brittle in the cold.. Greg I also agree that alloy could affect how it functions in cold Last edited by Gt Obach; 11th April 2005 at 02:51 AM.

11th April 2005, 03:59 PM	#6
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Hi Greg, Have a look at the picture. Close to the grip the watering is nice, but then it starts to change - why? Jens Attached Images

10th April 2005, 09:59 PM	#1
tom hyle Member Join Date: Dec 2004 Location: Houston, TX, USA Posts: 1,254	I may not follow you, but many swords, especially some of the finest European swords, are designed to break in certain places, if they break, as the distal taper to a thin tip and a thick soft base; the tip takes up much stress in its easy flex, though it cutting it can be vibratory, and I find slashing or drawing the cut helps, while the (sometimes) soft thick base and soft usually thick tang are greatly absorbant of all other shock/stress. Also, some were desinged with a breaking point in the tang, above (behind, pommelward of) a rivet, so if the tang does break, it's still attached. The geometry, simple or crystaline of this I do not understand, BTW, as I am not the best heavy pommel balancer, neither, but I've read of it, and seen its results, many times. Broken and damaged pieces are so educational to us, even if we don't repair them. Anyone got a snapped or chipped wootz blade to help us, maybe? Any modern smiths do toughness tests and find conditions/alloys/whatever where the steel is brittle? Everything is harder and more brittle when cold. I have seen hard steel axes hammers and files chip or snap way "too" easily when very cold. They were all, AFAIK, modern steel, though say early to mid 20th. Folklore of Europe is "the Vikings" the North-Germans, and specifically the Swedes invented the sword that could take the cold by pattern-welding; note we just got an Eastern version of this lore, too(?): However, also, this seems to be the "viking spatha/swert" known to history and archaeology as mostly Frankish(? or Burgundian?) in numbers manufactured, if not in origin/design (hmmmmm; like navajas......)

11th April 2005, 02:11 AM	#2
Chris Evans Member Join Date: Mar 2005 Location: Australia Posts: 685	Hi, The failure of swords in very cold climates is a fairly well known phenomena, indeed, as Tom so correctly points out, of all kinds of steel objects. I have heard of Japanese swords so failing in the very cold winters of Hokaido. Essentially, it us due to the `Brittle transition temperature' (BTT). The BTT is a temperature region at which the steel begins to lose all ductility and becomes exceedingly brittle. Alloying elements influence the BTT and it is determined by some kind of impact testing, usually by the Charpy or Izod tests, conducted over a range of temperatures. The temperature range at which the steel begins to exhibit brittle behaviour can thus be determined. The steels from which old swords were made were a pretty mixed lot, especially when it came to alloying elements. As such, their behaviour at low temperatures was unpredictable. Cheers Chris

11th April 2005, 03:01 PM	#4
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Hi Greg, You wrote: ‘I have made some swords of wootz.....and they all worked well.... preformed similarly to 5160 .... which is all I can tell’. What does 5160 mean? When you have hammered an ingot out, and see there are cracks, can’t you melt it down again and start all over? Jens

11th April 2005, 03:20 PM	#5
Gt Obach Member Join Date: Mar 2005 Posts: 116	Hi Jens 5160 is a carbon steel which has up to 1%Cr and .6 carbon.... therefore it is a medium carbon steel that deep hardens...... it works excellently for swords and other long blades... Cracking... the cracks are not the same ones that you find on some ingots ..... these cracks form as you are forging ..... they resemble the delaminations you find occuring with pattern welded blades... . - you could remelt the whole ingot......but this would cost alot of money.... 30lbs of propane and 40.00 for the crucible for the remelt....... it is better to grind out the crack.... and continue forging..... which has worked for me in the past..... -- you can never tell which ingot will turn out to be grumpy and disobedient....lol - in one experiment.....i left the delam and made it into a sword..... it worked fine....just have a big line in the middle of the blade.... it is unsightly Greg

11th April 2005, 06:22 PM	#7
tom hyle Member Join Date: Dec 2004 Location: Houston, TX, USA Posts: 1,254	BTW, let me just say that it has never been my impression that great strength, in general, was the reputed high magic of the wootz/bulat, but the magical cutting edge?

11th April 2005, 06:28 PM	#8
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Hi Tom, I am not sure that I agree to this, but I will have to come back to it later, as I don't have any more time at the moment. Jens