BESSEMER STEEL AND COLONEL EARDLEY WILMOT
Bessemer Pig -- Bessemer Steel works at Sheffield -- The first malleable Iron Gun -- Swedish Iron -- Investigations at Woolwich -- Bessemer steel-making at Sheffield
During the time that the works at Sheffield were being erected, I was very busy endeavouring to discover all the non-phosphoric iron ores in this country, and, after many analyses, the chief were found to be the hematites of Lancashire and Cumberland, and the Forest of Dean, and some spathose ores at Weardale and at Dartmoor. The hematite pig irons were, however, fatally contaminated with phosphorus, although some of these rich ores were absolutely free from this deleterious element. I found, on repeated analyses, that the mines of the Workington Iron Company yielded a very pure ore, but that their pig-iron contained much phosphorus. Here, at least, I had a field to work upon; and I wrote to the Secretary of the Company, asking him to name a day when I could go down and meet the Directors. An early date was fixed, and, at our interview I told the Directors that I, and many others, would become large buyers if they could make a pig-iron as free from phosphorus as the hematite ore was before smelting. I further said, that if they had no secrets, and would show me everything they were doing, I did not despair of finding out the source of contamination, and of pointing out a way of producing pure pig-iron that would command a ready sale wherever my process was carried on. The Board expressed their willingness to afford me every facility, and sent for their furnace-manager, who was instructed to take me over the works, answer all my questions, and furnish me with samples for analysis of all the raw materials they employed. I went round with him, and collected small samples for analysis of the coke obtained from different sources, the limestones from all the pits they worked, and samples of the hard and soft hematite ore from each of their different mines. The limestones contained but few shells, and I was quite at a loss to imagine where the phosphorus came from. As we were returning to the offices near one of the railway sidings, we came upon a large heap of slags and cinder. "What is that?" I asked the manager. "Oh, that is what we flux the furnace with," he said. "Yes, but what is it?" "It is a furnace slag, rich in iron," he replied. "We send into Staffordshire lots of our fine ore for fettling the puddling furnaces, and after they have done with it they send it back to us; in fact, we could not get a fluid cinder in our blast furnaces without it." "All right!" I said, "the cat is out of the bag now, and the mystery is all over." And so I found that the Staffordshire ironmaster, after purifying his phosphoric iron in the puddling furnace, and transferring its impurities to the hematite ore, sent the ore back again to Cumberland, and succeeded in spoiling the purest iron ore which this country possessed.
I was in high spirits at this discovery, for I now felt certain that we
should soon have thousands of tons of British iron suitable for the
production of steel by my process.
Before leaving the works, I arranged to take all these samples of raw
material to London, and get my own chemist to make a careful analysis.
Then, choosing the fittest materials in each case, furnace charges
could be formulated by our chemist, Professor Henry, of course omitting
the phosphoric slag, and substituting for it the dark shale of the coal
measures, so as to give a sufficiently fluid cinder. These theoretical
furnace charges were afterwards sent to the Workington Company, with
the following offer on our part, viz., the company were to use these
charges for at least twelve hours after they believed that all the old
materials had passed out of the blast furnace, so as to be quite sure
that the old impure matters had been entirely got rid of, and then
they were to run me 100 tons of this new pig-iron, which I undertook to
purchase, whatever its quality might be. They were instructed to make a
large letter B on the mould pattern used for casting, so as to
distinguish this pig from all others. This plan of marking was duly
carried out, and I got my 100 tons of "Bessemer Pig," the first that
ever was made. This brand of iron is, up to the present day, quoted in
all price lists, and in all the iron markets of the world, and has
placed at our disposal millions of tons of high-class iron, such as
had never before been produced in this country.
The new steel works of Henry Bessemer and Company, at Sheffield, had
been erected some months, and the first converter mounted on axes was
put to work in 1858. At first our attention was chiefly directed to the
manufacture of high-class tool steel, for which our quotation was £42
per ton, as against £50 or £60 by other makers. All this tool steel was
made from Swedish charcoal pig-iron, costing only about £3 per ton more
than English brands. The excellence of the steel so made is best proved
by the fact that during the two years that this branch of the steel
trade was carried on by us at Sheffield, we supplied such firms as Sir
Joseph Whitworth, Messrs. Beyer, Peacock and Company, Messrs. Sharp,
Stewart and Company, Sir William Fairbairn and Company, Messrs. Hicks,
of Bolton, Messrs. Platt Bros., of Oldham, etc. A moment's
consideration will show that such firms as those mentioned would never
have continued to use this steel if it had been in the slightest degree
inferior to the best steel made by the old process. By way of
commercial proof, let us suppose that our price was £14 per ton below
that of the trade. This would save precisely five farthings on the cost
of a tool weighing 1 lb. Now if such a tool during its whole life
occupied a workman (whose wages were seven-pence an hour) only twelve
minutes more in extra sharpening on the grindstone, the advantage of
£14 per ton would have been wholly lost. Is it, I would ask, probable
that the eminent engineering firms quoted would have continued to use
this Bessemer tool steel if the smallest shade of inferiority had
manifested itself? Our tool steel was also used at the Arsenal,
Woolwich, at the time when Colonel Eardley Wilmot, R.A., was
Superintendent of the Royal Gun Factories, prior to the advent of Sir
William Armstrong, and in confirmation of this fact I may quote the
following passage from the Proceedings of the Institution of Civil
Engineers, according to which, on May 24th, 1859, Colonel Wilmot, in
the course of a speech in reference to Bessemer Iron and Steel, said :--
We had now a large converting vessel erected at Sheffield, and
commenced operations on an extended scale. We were very anxious to see
how one of these large ingots would behave under the steam hammer, but
a delay had unfortunately taken place in the erection of our own large
hammer. In my impatience to see the result, I waited only until the
first heavy ingot ever cast at the works had cooled down sufficiently
to prevent it setting fire to the truck on which it was carried, before
I sent it by rail to Messrs. Galloway, at Manchester, who had a large
steam hammer in daily use. I followed by train, and saw the ingot
formed into a gun of the old-fashioned type. This gun is, in many
respects, a unique specimen of pure iron, and is now in the possession
of the Iron and Steel Institute. The ingot was made of Swedish charcoal
pig, costing £6 10s. per ton delivered in Sheffield; it was converted
into pure soft iron, and no spiegeleisen or manganese in any form was
employed in its production. This was not only the first large ingot
made at our works at Sheffield, but it was the first piece of ordnance
ever made in one piece of malleable iron, without weld or joint. It is
no less remarkable for its extreme purity. The metal of this gun had
originally been most carefully analysed, and many years later, during a
discussion at one of the Iron and Steel Institute meetings in 1879,
mention was made of its purity, a statement that was received with
incredulity. It was said that it was so near absolute iron that there
must have been some mistake in the analysis; whereupon it was proposed
by the President to have it again analysed.
Mr. Edward Riley, the well-known analyst of iron and steel, was
entrusted with this interesting investigation, and for this purpose the
gun was removed from the offices of the Institute to my laboratory and
workshops at Denmark Hill, and there put into the lathe. Shavings off
the muzzle of the gun were received on a sheet of clean white paper
held by Mr. Riley under the cutting tool, and were afterwards taken by
him to his own laboratory in Finsbury Square for careful analysis. This
occurred in the early part of March, 1879. A copy
of the analysis, which fully confirmed that originally made, is given
below.
Laboratory and Assay Offices,
2, City Road (14A, Finsbury Square),
London, E.C.
March 22nd, 1879.
EDWD. RILEY.
DEAR SIR,
Herewith I beg to forward you the results of my analysis of the sample
of steel turned from a small steel gun in my presence on Monday last.
The sample gave:
Henry Bessemer, Esq.
It is very generally known that of all the Swedish bar-irons, hoop L
Dannemora bar-iron is the purest brand to be met with in commerce. It
is these iron bars, which sell for £30 per ton and upwards, that are
used wholly, or in part, in making the highest class of crucible steel
produced in Sheffield. As an example of its purity, Dr. Percy, in his
well-known work on Metallurgy, gives the analysis of what he justly
calls "this world-renowned iron," and in order that there should be no
possible mistake on this point, I print below a portion of page 736 of
the volume devoted to iron and steel.
An examination of the specimens of Bessemer steel from Sweden in the
Exposition shows us that the metal there produced is of a far superior
character to that made in England, and naturally leads to inquiry as to
the cause of the difference, and whether we may hope to attain the
same success in the United States. First we observe coils of wire of
all sizes, down to the very finest, such as No. 47, or even smaller.
This they have not
been able regularly to produce in England. In the next place we notice
a good display of fine cutlery, and the writer is informed by a
competent authority that this metal answers so well for this purpose
that it is now used almost to the exclusion of any other. This
statement is corroborated by the fact that in the miscellaneous classes
of the Swedish department, where cutlery occurs not as an exhibition of
steel, but merely as a display of workmanship by other parties in the
same manner as other articles of merchandise, cases of razors are
exhibited with the mark of the kind of steel of which they are made
stamped or etched upon them as usual, and these are all "Bessemer," but
from a variety of different works, viz., Högbo, Carsdal, Osterby, and
Söderfors. The ore used in Sweden for producing iron for the Bessemer
process is exclusively magnetic, and of a very pure quality. An
analysis of a mixture of those used for the iron employed at the
Fagersta works before roasting gives the following composition:--
All the pig made from this mixture of ores the exhibitors state will
give a steel without the use of spiegeleisen, which is not at all red
short. The analysis of gray iron from the same works, used for the
Bessemer process, is given as follows:--
From these examples, 2, 3, and 4 of hoop L bar-iron, we have for No. 2,
pure iron 99.863 per cent.; for No. 3, pure iron 99.220; and for No. 4,
pure iron 98.605; giving a mean of 99.220 of pure iron in these three
samples of hoop L.
Now, by Mr. Riley's analysis, we have only two testings of the Bessemer
malleable iron gun, the first giving 99.893 per cent. of pure iron, and
the second one 99.787, a mean of 99.840 per cent. of pure iron, or
00.611 more than Dannemora bar.
Since the Dannemora iron mines achieved their deservedly high
reputation, many new mines had come into operation in Sweden, at which
pig-iron only was made, and it was the products of these mines that I
had analysed for my special use, and thus discovered that some of them
were producing pig-iron of extreme purity. Thus I was enabled to make
malleable iron or steel of the highest quality from Swedish pig,
costing, delivered in Sheffield, £6 l0s. to £7 per ton, and yielding,
from my converter, ingots of cast steel of great purity at a cost of
less than £10 per ton, fully equal to that made from Swedish bar
costing £30 per ton, such bar being only the raw material for the old
crucible process of making steel.
From a consideration of these facts, it will be readily understood how
we could produce cheap high-class tool steel, while for general uses we
had obtained native pig-iron -- "Bessemer pig" -- smelted with coke,
admirably adapted for the production of steel for all structural
purposes, for which it was in every way superior to the highest brands
of iron previously known in this country.
I had no sooner arrived at these results on a commercial scale than I
again put myself in communication with Colonel Eardley Wilmot, the
Superintendent of the Royal Gun Factory at Woolwich Arsenal, for I had
never lost sight of the original object of my research a metal suitable
for the construction of ordnance. It was, in fact, this idea that had
led, step by step, to the discovery of my process. I was the more
pleased to communicate these facts without delay to the authorities at
Woolwich, because, in the person of Colonel Eardley Wilmot, I found a
zealous officer, who took the deepest interest in any improved
materials or processes that could be advantageously employed in the
founding or construction of ordnance. He, fortunately, had no pet
schemes of his own to promote, and was neither a patentee nor a
private manufacturer; he was, in fact, an officer whose sole aim and
ambition was to arrive at the highest perfection and development of the
department over which he so ably presided, wholly without reference to
the sources from which such improvements were derived.
It was now many months since I had reported myself at Woolwich, but on
my communicating the fact that we were commercially successful
in producing both pure and malleable iron in masses, and steel of any
degree of carburisation that might be desired, at a price far below
that of the best bar iron, and in masses of almost any assignable
weight, the information immediately riveted Colonel Wilmot's attention.
His old hopes of having a superior metal for guns seemed suddenly to
revive, and he became deeply interested in all that I had to
communicate. After a very protracted discussion, I left with a promise
to send him several different qualities of our steel for analysis,
testing for tensile strength, etc.
These investigations at Woolwich lasted over a period of several
months, during which time I frequently called to see Colonel Wilmot,
and sometimes to see Professor (afterwards Sir Frederick) Abel,*[1]
who was at the head of the chemical laboratory, where a great number of
analyses were, from time to time, made and communicated to me. Many
interesting tests were also made by drawing down a portion of an ingot
first, to two-tenths in additional length, and then to four-tenths, and
so on. Some portions were elongated to five times their original
length, each piece being tested to show the true amount of increased
strength given to it by additional forging and elongation of the bar.
In fact, Colonel Wilmot left no stone unturned to arrive at the actual
facts of the case, and a full knowledge of the strength and properties
of the new material. Some of the tests above mentioned have been lost,
but I have still twenty-nine well-authenticated records showing the
extreme tenacity and toughness of the metal. On one occasion I
happened to remark to Colonel Wilmot that such was the extraordinary
ductility of our cast malleable iron and mild cast steel, that I had no
doubt a thick gun-tube might be collapsed, and hammered up quite flat,
under the steam-hammer, whilst perfectly cold, without showing any
tendency to crack or burst open. Colonel Wilmot observed that,
notwithstanding the numerous proofs he had had of its marvellous
tenacity, he thought that no material could possibly undergo such a
severe ordeal without fracture. "Well," I said, "it will be an
interesting experiment, even if it fails, and I will put it to the test
if you wish it." I accordingly had an
ingot of mild steel, and one of wholly decarburised iron, forged until
they were extended to about double their original length. Two portions
of each were cut off, turned, and bored in the lathe, and then
beautifully finished both inside and out, the length and diameter of
each cylinder being 6 in. and the thickness of metal 3/4 in. These
pieces of gun-tube were bored to 4 1/2 in., in diameter -- a size
suitable for a 40-pounder gun. I personally took these four tubes down
to Woolwich, and was present with Colonel Wilmot when they were placed
in succession (while cold) under the large steam hammer, and crushed
flat, each tube being quite closed up. In no case was there the
slightest indication of either tearing or rupture at any part of their
surfaces.
Colonel Wilmot was greatly astonished, and so was the experienced
foreman of the hammer shop who conducted the experiment, and who
expressed his admiration with a forcible adjective, which I need not
repeat. I gave one steel and one pure iron cylinder to Colonel Wilmot,
and retained the other two, which were exhibited in the International
Exhibition of 1862.
After personally inspecting the crushing of the two pure iron cylinders
and the two mild steel ones, Colonel Wilmot was so convinced of the
immense importance to the State of Bessemer mild steel as a material
for guns, that he said he would no longer delay taking active steps
for its manufacture at Woolwich. On his asking me if he might go over
our Sheffield Works, and see for himself how everything was done, I at
once assented. A day was fixed, and Colonel Wilmot and I went down
together to Sheffield, where he passed the greater part of the
following day in making himself fully acquainted with all the details
of what was in reality a very simple process, and with which he
expressed himself perfectly satisfied. I cannot omit to mention a very
curious and somewhat significant fact, which more than justified
Colonel Wilmot in the strong opinion he had formed of the value and
practicability of the process. The well-known and extensive steel works
of Sir John Brown and Co. are only separated by a wall from the
Bessemer Steel Works at Sheffield, but neither Sir J. Brown, nor any of
his people, had taken the smallest apparent interest in what we were
doing, and, indeed, like the rest of the good people at Sheffield, had
a profound disbelief in the production of steel direct from pig-iron
by any conceivable process. Now Colonel Wilmot, during this visit to
Sheffield, had occasion to see Sir John Brown on other business, and,
so ardent a convert had he become, that he succeeded in persuading Sir
John Brown and his partner Mr. Ellis, to go with him next door and see
the Bessemer process in operation. They came, and had but a short time
to wait before the cupola furnace was tapped, and a charge of molten
pig-iron was run by a spout directly into the empty converter. They
seemed much interested in watching the great change which took place
in the flame and sparks emitted as the process proceeded; but when the
eruption of cinder, and the accompanying huge body of flame, were seen
to issue from the converter, they were greatly astonished. In about
twenty minutes the flame had dropped, the mouth of the huge vessel was
gradually lowered, and a torrent of incandescent metal was poured into
the casting ladle. Up to this moment they merely expressed surprise at
the volume of flame, the brightness of the light, and the entire
novelty of the process. But no sooner did they see the incandescent
stream issue from the mouth of the converter, than their practised eyes
in an instant recognised it to be fluid steel, and they themselves were
"converted," never to fall back again into a state of unbelief. They
stayed to witness the casting operation, and accepted one of the hot
ingots for testing at their own works, the result being that Sir John
Brown and Company became the first licensees in Sheffield under my
steel patents.
The moral to be drawn from these facts is simply this;-- that the state
of the manufacture was at that period such, that after once witnessing
the process and testing the material at their own works, these
eminently practical steel-makers resolved, at the risk of entirely
revolutionising their old established business, to put up plant and
become Bessemer Steel manufacturers. Now, I would ask any impartial
person if this fact did not justify, and more than justify, Colonel
Wilmot in the conclusion to which he had arrived independently -- that
this cheap and rapid production of steel ought at once to be utilised
in the manufacture of guns for the British Government.*[2]
After my return to London, I waited on Colonel Wilmot by appointment,
went with him to inspect the gun-foundry at the Arsenal, and chose a
suitable spot for the erection of the Bessemer Steel plant. It was
finally arranged by us to remove one of the three large reverberatory
furnaces that had been used to melt pig-iron for casting guns, and in
its place put up a pair of converters, utilising the other two furnaces
for melting the Bessemer pig. I took accurate measure of the foundry
and its contents, so as to enable me, at my own offices, to arrange all
the details of a converting plant to be erected in the old gun-foundry
and to make an estimate of the cost.
When this was done, I handed to Colonel Wilmot an approximate estimate
of £6,000, for erecting a steam-engine, boilers, and converting plant
of sufficient size to produce 100 tons of gun steel per day, and I
guaranteed that the cost of the steel poured into their own moulds
should not exceed £6 10s. per ton, when hematite pig-iron was used, or
£10 per ton when Swedish charcoal pig-iron was employed: my
remuneration being a royalty of £2 per ton on all metal converted, the
same as charged to all private manufacturers.
Footnotes
[2] On the occasion of my reading a Paper at the Institution of Civil
Engineers, on The Manufacture of Iron and Steel, in May, 1859, Colonel
Wilmot said, in reference to a
very silly observation of one of the members: "As regards the
difficulty of the process, as well as the results of it, he thought the
best thing for a member of a practical society to do was to follow his
example, and go and see it for himself; nothing could be more simple
or more perfectly under control." (Excerpt: Minutes of Proceedings of
the Institution of Civil Engineers.)
As regards the steel, he had been using it for turning the outsides of
heavy guns . . . . . cutting off large shavings several inches in
length, and he has found none other superior to it, although much more
costly.
Indeed, Colonel Wilmot exhibited to the meeting a box full of
exceptionally
large and heavy shavings taken off by this steel, in the ordinary
course of turning in the lathe.
Carbon . . .014
Silicium . . .004
Sulphur . . .052
Phosphorus . . .047 .046
Iron . . 99.893 99.787
Manganese . nil.
Copper minute trace
---------
100.010
---------
Believe me to remain,
Yours very faithfully,
EDWD. RILEY, F.C.S.
Metallurgist, Analytical and Consulting Chemist.
Carb. acid . . 8.00
Silicium . . 17.35
Alumina . . 0.95
Lime . . 6.50
Magnesia . . 4.35
Protoxide of manganese . 3.35
Magnetic oxide . . 32.15
Peroxide of iron . 27.40
--------
100.05
Phosphoric acid . 03
Carbon combined . . 1.012
Graphite . . 3.527
Silicium . . 0.854
Manganese . . 1.919
Phosphorus . . 0.031
Sulphur . . 0.010
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[1] Died, September 6th, 1902.