Ingots

[Jeff Pringle]

Since the last time this topic cropped up I found another photo of an original ingot, and a good illustration or two of the crucibles used to make them (which, of course, define the shape of the ingot ). The easy diagnostic feature on ingots is going to be some evidence of a former meniscus (that curve of the surface that contained liquids have near the edge) where the liquid steel met the crucible wall...here are two real ingots, three crucible shapes and some steel shot from a ball mill, you can see the complete lack of similarity!

[Jens Nordlunde]

Jeff, Thank you very much for your post and the pictures.
Form this, there is no doubt what mill balls look like, so you have cleared that problem very well - once an for all .
Jens

[Oriental-Arms]

This is not an attempt to prove that these are wootz ingot or mill balls. It was discussed many times in several forums so I will leave it to the expert to decide. But since I was offering for sale few of these wootz/mill balls I feel I should share with you some facts and findings
I sacrificed one of this balls and submitted it to the good hands of Giora Biran, a blacksmith and a friend and this is what we have done:
The ball was cut into two halves with a disk and one of the faces flattened.





(Please note the crack in the center, also known as “pipe”. I will refer to it later.)

One half was heated to about 800 degrees and hammered down (in several heating cycles) to a flat bar shape:







One face was polished and etched to reveal a very clear pattern:



A small part of the bar was further forged to a small kitchen style blade (more and bigger blades are being worked out now), polished and etched:

[Oriental-Arms]

The Facts:
1)These balls are definitely coming from India. They are supposedly coming from an old armory but I can not substantiate it.
2) In the pile of several tenth balls that I have seen, many were of quite a symmetrical shape, few of non regular shape and all has the depression on one side.

The findings:
1) These balls were cast in a crucible. The depression and the “pipe” seen on the cut ball is very typical to what happens in the cooling process in the crucible.[br]

2) It is hard steel. We did not measured the exact hardness but Giora estimate it to be (after hardening) around 60

3) The pattern is clear and very similar to what we have seen on Old Indian wootz blades.

The open questions:
1) To start with, why to use cast steel ball for milling? It is far more common to use white cast iron for this task. It has a harder shell and it is definitely cheaper. The milling process require hundreds of balls, so all were cast each in a separate crucible ?? It is quite expensive.
2) In the early 20th C. (the age suggested in a previous thread for this balls) perfect shape balls were easily available, from a variety of materials and sizes. So again why to use crucible cast steel balls?
3) After a short while in the drum the mill balls will definitely get a non regular shape (but will never have the depressions we see here). In the pile of balls I have seen most of the balls had a perfect symmetrical shape. Does this mean that they are all un-used? Below is a photo of two mill balls I personally collected from an abandoned lime stone quarry (abandoned in the 50th). They are made of cast white iron and has the typical shape after use

[br]
4) The chemical composition of the balls may be a key to answer many of the questions. I am planning to do it and I will gladly report further findings

p.s: I had a private correspondence with Jeff Pringle regarding this issue. We are not in agreement and I hope he will post here his opinion.

[Richard Furrer]

I feel I must put my foot in here as well.
I was sent one of these ingots by Artzi many years ago I have not forged it as I said I would..it is still in ingot/ball form and I am shamed for not getting to this sooner.
I will have it chemically tested for elements.

While in India I saw many of these at a friend's shop in Udiapur and asked for a sample..it had 14% chromium when tested and did forge out to a nice pattern.
I will post images when I locate them. Some of these balls were as large as oranges others as small as grapes.

Ric

[Jeff Pringle]

Yes, we have a difference of opinion on these
Regarding the facts:
1) They also come from America, so origin is immaterial
2) The shape is not consistent with ancient ingots, so symmetry or depression also does not matter

Regarding the findings:
1) Definitely NOT cast in a crucible. The depression is the wrong shape to be derived from solidification shrinkage, the internal porosity is in the wrong place to be associated with the depression.
2) & 3) also immaterial

Regarding the open questions:
1) Choice of grinding media is governed by hardness and specific gravity of the material to be crushed, there is no reason to think cast iron is more common. Several types of cast steel shot are commonly available.
2) Because we have evidence of cast steel being used, it clearly must be one of the economically viable options, no need to ask why.
3) This is immaterial, since there is no reason to think they are ingots, why speculate on how they wear away in the mill? But there is no reason to assume the process is not random, generating symmetric and asymmetric forms.
4) This will of course be a good idea!
I admit my opinion is colored by having first run across these in a very non-wootz context, but the shape of the ones sold from India and some of the ones I found at a mine in the US are identical.

[Mare Rosu]

Jeff you did a great job in answering the questions as well showing us where you got the mill balls.
As to question #4

Below is a extract from an article by Verhoeven, Pendray and W.E. Dauksch, "The Key Role of impurities in Ancient Damascus Steel Blades":

http://www.tms.org/pubs/journals/jom...even-9809.html

Take a look at the whole article as it has the pictures and much more information on wootz testing.


The article showers the chemical composition of wootz from several old blades.
A most interesting point is that one of the wootz blades,( sword #8 ) long identified as wootz by the museum as well as others is in fact not wootz at all, according to Verhoeven. Indicating "eye ball" testing of the pattern is NOT the the way to tell wootz from non wootz.
Gene


"THE SWORDS
Figure 2. Macrophotographs of Zschokke sword blades.
A major problem in doing scientific experiments on wootz Damascus steel is the inability to obtain samples for study. Such study requires that the blades be cut into sections for microscopic examination, and small quantities must be sacrificed for destructive chemical analysis. A rare example where museum-quality wootz Damascus blades were donated to science for study is reported in the 1924 paper of Zschokke.13 A famous explorer and collector, Henri Moser, amassed a collection of some 2,000 Damascene blades and donated two daggers and four swords to Zschokke for study. The Moser collection is now displayed in the Berne Historical Museum in Switzerland, and the remaining pieces from the four swords of the Zschokke study remain there. Recently, Ernst J. Kläy of the Berne Museum donated a small sample of each sword for further study to be conducted.
This article presents the results of a study of these four samples. Also, four additional wootz Damascus blades, all thought to be a few hundred years old, have been acquired and are included. Hence, all of the blades studied here are more than two centuries old and were presumably made from wootz steel. These blades are referred to as genuine wootz Damascus blades to differentiate them from the reconstructed wootz Damascus blades made by the technique developed by the authors.


Zschokke Swords
Zschokke identified the four swords of his study as swords 7-10, and the same code is used here. The swords had an original width of around 30 mm. The samples provided were approximately 18 mm wide by 88 mm in length and contained the cutting edge. The surface of the samples were refinished by polishing with fine SiC papers and then etching in ferric chloride. The contrast on the sample's surface was enhanced by applying the ferric chloride with repeated rubbing from a cloth. Figure 2 presents macrographs of the four sword samples; sword 9 has the most distinct pattern.
Pieces were cut from one end of each of the samples with a thin diamond saw. A 2 cm length was cut for chemical-analysis studies, and an 8 mm length sample was used for microstructure analysis. The chemical analyses were done using emission spectroscopy on a calibrated machine at Nucor Steel Corporation. Table I presents the chemical analyses, along with the values reported by Zschokke. Agreement between the analyses done by Zschokke in 1924 and the present data is reasonably good.


Table I. A Comparison of the Current Chemical Analyses with Zschokke's Analyses13*
Sword 7 Sword 8 Sword 9 Sword 10
Material Current Zschokke Current Zschokke Current Zschokke Current Zschokke
C 1.71 1.87 0.65 0.60 1.41 1.34 1.79 1.73
Mn 150 50 1,600 1,590 <100 190 300 280
P 1,010 1,270 1,975 2,520 980 1,080 1,330 1,720
S 95 130 215 320 60 80 160 200
Si 350 490 1,150 1,190 500 620 500 620
* Analyses are given in parts per million by weight, except for C, which is in weight%.


Sword 8 is hypoeutectoid and, therefore, cannot be a true wootz Damascus steel, because such steels will not form Fe3C particles on cooling. Metallographic examination confirmed this expectation and revealed that the surface pattern seen on this sword (Figure 2) was due to ferrite bands in a pearlite matrix. Therefore, this sword will not be considered to be a genuine wootz Damascus sword in the following discussion.
Micrographs of surface and transverse sections of the remaining three swords are shown in Figure 3. The micrographs of the surfaces are, in effect, taper sections through the bands seen on the micrographs of the section views, and, as expected, the widths of the bands are expanded in the surface views."