16th Century Italian Bulat (wootz) -- myArmoury.com

Lawrence Parramore

Ok, only half serious, but I have read today a piece from Dr Williams Knight and the Blast Furnace, on page 886 he outlines a translation that reads to me like the production of Bulat in Brescia in around 1540, anybody familiar with this, has it already been discussed?

Lawrence

Lawrence Parramore · Posted: Sat 14 Jun, 2008 4:02 am Post subject:

Nobody has an opinion on crucible steel in 16th century Italy?

Chad Arnow · myArmoury Team

Jeff Demetrick

Lawrence Parramore · Posted: Sat 14 Jun, 2008 8:09 am Post subject:

I don't think I can without infringing, the basics are, a crucible with cast iron in it and then introducing 'wrought iron' into this to produce a homogeneous steel without flaws, and this is the way they produced bulat in Tashkent or somewhere near there I remember reading, quite a different process to Wootz in India.

Lawrence

Chad Arnow · myArmoury Team

Here's what Wikipedia has to say, which can always be taken with varying amounts of salt Happy

:

http://en.wikipedia.org/wiki/Bulat_steel

Jeff Demetrick · Posted: Sat 14 Jun, 2008 9:00 am Post subject:

Hi Lawrence,

There should be no infringement problems as long as you site your sources. Wootz steel refers to iron carbonized in a oxygen deprived environment (sealed crucible), with the end product having a distinctive pattern. The process you describe is the mixing of high and low carbon steels. The molten high carbon will mix with the partially molten low carbon steels to cause some diffusion of the carbon, not the total diffusion and equilization of the crucible wootz. The mixing method apparently was well known from the middle ages on.

All the Best
Jeff

Lawrence Parramore · Posted: Sat 14 Jun, 2008 9:10 am Post subject:

Yes that is why I say Bulat as opposed to wootz which is a different process.

I will try and find the report of the excavation where they found the method of Bulat.

And I''ll try and scan the report, thanks for that though, so it was a well known process.

Lawrence Parramore · Posted: Sat 14 Jun, 2008 10:37 am Post subject:

Hi here is an excerpt from a report on the report, did not find the original yet;

Known as "co-fusion", the technique involved heating small pieces of solid wrought iron with cast iron, until the latter melts. Some of the cast iron's carbon diffuses from the melt into the wrought iron (which only melts partially), producing a workable, durable steel. The final carbon content and quality of the steel depends on the extent to which the metals melt, or fuse together. Co-fusion produces steel at temperatures several hundred degrees lower than the 1500 °C melting point of true cast steel, because you only need initially to liquefy the cast iron in the crucible.

And here is a link; http://technology.newscientist.com/article/mg...ports.html

I also read another report from excavations at Merv where they have found that they also produced it straight from ore.

Lawrence

Tried scanning the Williams, but my scanner wont co-operate with the computer!!!!!

Peter Johnsson · Industry Professional

The crucible part of this process is to hold the molten cast iron, keeping it hot, not the actual producing of steel.
Cast iron has lower melt temp than the iron bar/rod that is introduced. The will get glowing hot, but not melt.

Stirring the rod/-s from time to time in the molten cast iron and letting the carbon diffuse into the iron at the high temp.
It is a kind of "case hardening" or rather carburization, not a full melting of iron together with cast iron like in a cruicble steel process.
The carburized rods were later forged together and reforged into themselves a few times to homogenize the carbon content.
A kind of blister steel.

Lawrence Parramore · Posted: Sat 14 Jun, 2008 11:57 am Post subject:

I understand where you are coming from, that was done in Europe in the nineteenth century and most likely the process in Brescia, but the ones at Merv were sealed so could not be stirred. The cast iron would run where the slag was in the 'wrought iron' pushing it out and producing a lovely layered effect as I understand it without melting the wrought but 'welding' with it and partially carburiseing the wrought and lowering the cast iron content to the level where it became steel.

I may try this process when I have my mind to it.

Torsten F.H. Wilke · Posted: Sat 14 Jun, 2008 12:44 pm Post subject:

So, this process effectively brazed the wrought iron rods together, while slightly carburizing them? Very interesting...

How thick do you think these wrought bars or rods were in general, and how well would this hold up to further forging in order to achieve a blade form? Also, I am no expert in metallurgy, but does the graphite ever truly go into solution when cast iron is in the molten state? That might present a hinderance in getting the cast iron to become more steel-like during this process, unless the carbon diffusion time at those temps was quick enough.

Lawrence Parramore · Posted: Sat 14 Jun, 2008 12:50 pm Post subject:

Brazed is not a good term for this process I don't think?

He is talking 15-20 kilos and many hours, though he does not think it would take that long from a metallurgical standpoint and as the crucible is open the carbon will also be being burnt off presumably?

Lawrence

Bruno Giordan · Posted: Wed 18 Jun, 2008 1:06 am Post subject:

I have just read that in the XVI century iron from Vallecamonica (Brescia) would be mingled with iron from Val di Scalve (Bergamo) in order to attain a good quality metal for armorers.

Alone his iron would be of considered of scarce quality.

It might be what Lawrence is speaking of, a mingling of at iron and iron to attain steel.