Crucible steel blades

Jens Nordlunde · 8th October 2006, 05:10 PM

Thanks Greg,

I seem to remember that it, in some places in Siberia, can be as cold as –70 C during winter, but this is in special places, not everywhere. I have never tried –40 C, only –25 C, and I found that pretty cold, as it always blows where I lived at the time.

From the text it seems as if the Rus’s/Vikings swords had a bigger chance to ‘survive’ than the blades made of crucible steel. I know the description says a softer core and hard edges, but somewhere else I have seen that they also used soft and hard steel forged together.

On page 169 he writes: “Phosphorus affects the hardness as well as giving the iron very pale etching optical properties”. The two authors don’t agree much with the last statement, and earlier in the book they state that al-Biruni is less reliable than al-Kindi, but what about the Phosphorous affect?

If you don’t have the book, maybe you should try to have a look at it in a library – I think toy will like it.

Jens

Jeff Pringle · 8th October 2006, 05:28 PM

Carbon makes steel brittle in general, not just at cold temperatures. Over 1 % C, the amount of carbide increases and the carbides form at grain boundaries, reducing the strength of the grain boundary. Wootz blades are heat treated in such a way as to minimize the bad effects of having a lot of excess carbide, to take advantage of their excellent edge enhancing properties.
Sulfur makes the steel more prone to cracking while it is being worked ‘hot’, phosphorus makes it more brittle when ‘cold’ – hot and cold meaning ~1500 F + and room temp, respectively. Phosphorus also collects at grain boundaries, and produces brittleness under shock – not good for a sword blade.
I think phosphorus is the culprit in this case, or the combination of high carbon and phosphorus. Verhoeven said in one of his JOM articles that he thought that Phosphorus was needed for good pattern development in wootz. Which one comes into play more as the temperature goes from +60 F to -20 F, or if it’s the synergy of both - I don’t know if that’s been determined.

Thanks for the heads-up on that book, ‘Medieval Islamic Swords and Swordmaking’ – I think Gilmore hinted that would be on the way in ‘Persian Steel’, but I hadn’t noticed it was out.

Greg - the low temps would get the retained austenite to go to untempered martensite? That would increase breakage, for sure! I think you should go ahead with that wordy post.

8th October 2006, 05:10 PM	#1
Jens Nordlunde Member Join Date: Dec 2004 Location: Europe Posts: 2,718	Thanks Greg, I seem to remember that it, in some places in Siberia, can be as cold as –70 C during winter, but this is in special places, not everywhere. I have never tried –40 C, only –25 C, and I found that pretty cold, as it always blows where I lived at the time. From the text it seems as if the Rus’s/Vikings swords had a bigger chance to ‘survive’ than the blades made of crucible steel. I know the description says a softer core and hard edges, but somewhere else I have seen that they also used soft and hard steel forged together. On page 169 he writes: “Phosphorus affects the hardness as well as giving the iron very pale etching optical properties”. The two authors don’t agree much with the last statement, and earlier in the book they state that al-Biruni is less reliable than al-Kindi, but what about the Phosphorous affect? If you don’t have the book, maybe you should try to have a look at it in a library – I think toy will like it. Jens

8th October 2006, 05:28 PM	#2
Jeff Pringle Member Join Date: Nov 2005 Posts: 189	Carbon makes steel brittle in general, not just at cold temperatures. Over 1 % C, the amount of carbide increases and the carbides form at grain boundaries, reducing the strength of the grain boundary. Wootz blades are heat treated in such a way as to minimize the bad effects of having a lot of excess carbide, to take advantage of their excellent edge enhancing properties. Sulfur makes the steel more prone to cracking while it is being worked ‘hot’, phosphorus makes it more brittle when ‘cold’ – hot and cold meaning ~1500 F + and room temp, respectively. Phosphorus also collects at grain boundaries, and produces brittleness under shock – not good for a sword blade. I think phosphorus is the culprit in this case, or the combination of high carbon and phosphorus. Verhoeven said in one of his JOM articles that he thought that Phosphorus was needed for good pattern development in wootz. Which one comes into play more as the temperature goes from +60 F to -20 F, or if it’s the synergy of both - I don’t know if that’s been determined. Thanks for the heads-up on that book, ‘Medieval Islamic Swords and Swordmaking’ – I think Gilmore hinted that would be on the way in ‘Persian Steel’, but I hadn’t noticed it was out. Greg - the low temps would get the retained austenite to go to untempered martensite? That would increase breakage, for sure! I think you should go ahead with that wordy post.