William Metcalf.

Steel: a manual for steel users online

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Copyright, 1896,





TWENTY-SEVE:N" years of active practice in the manufact-
ure of steel brought the author in daily contact with ques-
tions involving the manipulation of steel, its properties, and
the results of any operations to which it was subjected.

Blacksmiths, edge-tool makers, die-makers, machine-
builders, and engineers were continually asking questions
whose answers involved study and experiment.

During these years the Bessemer and the open-hearth
processes were developed from infancy to their present
enormous stature; and the shadows of these young giants,
ever menacing to the expensive and fragile crucible, kept
one in a constant state of watching, anxiety, and more

The literature of steel has grown with the art; its books
are no longer to be counted on the fingers, they are to be
weighed in tons.

Then why write another ?

Because there seems to be one little gap. Metallurgists
and scientists have worked and are still working; they have
given to the world much information for which the world
should be thankful.

Engineers have experimented and tested, as they never
did before, and thousands of tables and results are re-




corded, providing coming engineers with a mine of inval-
uable wealth. Steel-workers and temperers have written
much that is of great practical value.

Still the questions come, and they are almost always
those involving an intimate acquaintance with the proper-
ties of steel, which is only to be gained by contact with both
manufacturers and users. In this little manual the effort
is made to fill this gap and to give to all steel-users a sys-
tematic, condensed statement of facts that could not be ob-
tained otherwise, except by travelling through miles of
literature, and possibly not then. There are no tables, and
no exact data; such would be merely a re-compilation of
work already done by abler minds.

It is a record of experiences, and so it may seem to be
dogmatic; the author believes its statements to be true
they are true as far as his knowledge goes; others can
verify them by trial.

If the statements made prove to be of value to others,
then the author will feel that he has done well to record
them ; if not, there is probably nothing said that is likely
to result in any harm.




FACTURE. Cemented or Converted Steel. Blister, German,
Shear, Double-shear. Crucible- steel, Bessemer, Open-
hearth 1


STEEL. Crucible, Open-hearth, Bessemer 14

ALLOY STEELS AND THEIR USES. Self-hardening, Manganese,

Nickel, Silicon, Aluminum 27


CARBON. General Properties and Uses. Modes of Introducing
It in Steel. Carbon Tempers, How Determined. The Car-
bon-line. Effects of Carbon, in Low Steel, in High Steel. Im-
portance of Attention to Composition 37


Plastic, Granular, Liquid. Effects of Heat. Size of Grain.
Recalescence, Magnetism. Effects of Cooling, Hardening,
Softening, Checking. Effects of Forging or Rolling, Hot
or Cold. Condensing, Hammer- refining, Bursting. Ranges
of Tenacity, etc. Natural Bar, Annealed Bar, Hardened Bar,
etc 52




HEATING. For Forging; Hardening; Overheating; Burning; Re-
storing; Welding 77



HARDENING AND TEMPERING. Size of Grain; Refining at Recal-
escence; Specific-gravity Tests; Temper Colors; How to Break
Work; a Word for the Workman 96

EFFECTS OF GRINDING. Glaze, Skin, Decarbonized Skin,

Cracked Surfaces, Pickling 123


IMPURITIES AND THEIR EFFECTS. Cold-short, Red-short, Hot-
short, Irregularities, Segregation, Oxides, etc., Wild Heats,
Porosity. Removing Last Fractions of Hurtful Elements.
Andrews Broken Rail and Propeller-shaft 129


THEORIES OF HARDENING. Combined, Graphitic, Dissolved,
Cement, Hardening and Non-hardening Carbon. Carbides.
Allotropic Forms of Iron a, ft. ,ecc. Iron as an Igneous Rock
or as a Liquid 146


INSPECTION. Ingots, Bars, Finished Work. Tempers and Sound-
ness of Ingots. Seams, Pipes, Laps, Burns, Stars. 151


SPECIFICATIONS. Physical, Chemical, and of Soundness and
Freedom from Scratches, Sharp Re-entrant Angles, etc 154






STEEL may be grouped tinder four general heads, each
receiving its name from the mode of its manufacture; the
general properties of the different kinds are the same,
modified to some extent by the differences in the operations
of making them; these differences are so slight, however,
that after having mentioned them the discussion of
various qualities and properties in the following pages will
be general, and the facts given will apply to all kinds of
steel, exceptions being pointed out when they occur.

The first general division of steel is cemented or con-
verted steel, known to the trade as blister-steel, German,
shear, and double-shear steel.

This is probably the oldest of all known kinds of steel,
as there is no record of the beginning of its manufacture.
This steel is based upon the fact that when iron not satu-
rated with carbon is packed in carbon, with all air excluded,


and subjected to a high temperature, any temperature
above a low red heat, carbon will be absorbed by the iron
converting it into steel, the steel being harder or milder,
containing more or less carbon, determined by the tempera-
ture and the time of contact.

Experience and careful experiment have shown that at
a bright orange heat carbon will penetrate iron at the rate
of about one eighth of an inch in twenty-four hours. This
applies to complete saturation, above 100 carbon; liquid
steel will absorb carbon with great rapidity, becoming
saturated in a few minutes, if enough carbon be added to
cause saturation.


Bars of wrought iron are packed in layers, each bar sur-
rounded by charcoal, and the whole hermetically sealed in a
fire-brick vessel luted on top with clay ; heat is then applied
until the whole is brought up to a bright orange color, and
this heat is maintained as evenly as possible until the whole
mass of iron is penetrated by carbon; usually bars about
three quarters of an inch thick are used, and the heat is
required to be maintained for three days, the carbon,
entering from both sides, requiring, three days to travel
three eighths of an inch to the centre of the bar. If the
furnace be running hot, the conversion may be complete
in two days, or less. The furnace is then cooled and the bars
are removed; they are found to be covered with numerous
blisters, giving the steel its name.

The bars of tough wrought iron are found to be con-
verted into highly crystalline, brittle steel. When blister-
steel is heated and rolled directly into finished bars, it is
known commercially as



When blister-steel is heated to a high heat, welded
under a hammer, and then finished under a hammer either
at the same heat or after a slight re-heating, it is known as


When single-shear steel is broken into shorter lengths,
piled, heated to a welding heat and hammered, and then
hammered to a finish either at that heat or after a slight
re-heating, it is known as


Seebohm gives another definition of single-shear, and
double-shear; probably both are correct, being different
shop designations.

Until within the last century the above steels were the
only kinds known in commerce. There was a little steel
made in India by a melting process, known as Wootz. It
amounted to nothing in the commerce of the world, and is
mentioned because it is the oldest of known melting

Although converted steel is so old, and so few years ago
was the only available kind of steel in the world, nothing
more need be said of it here, as it has been almost super-
seded by cast steel, superior in quality and cheaper in cost,
except in crucible-steel.

Inquiring readers will find in Percy, and many other
works, such full and detailed accounts of the manufacture
of these steels that it would be a waste of space and time
to reprint them here, as they are of no more commercial


In the last century Daniel Huntsman, of England, a
maker of clocks, found great difficulty in getting reliable,
durable, and uniform springs to run his clocks. It oc-
curred to him that he might produce a better and more uni-
form article by fusing blister-steel in a crucible. He tried
the experiment, and after the usual troubles of a pioneer
he succeeded, and produced the article he required. This
founded and established the great Crucible-cast-steel in-
dustry, whose benefits to the arts are almost incalculable;
and none of the great inventions of the latter half of this
nineteenth century have produced anything equal in quality
to the finer grades of crucible-steel.


is the second of the four general kinds of steel mentioned
in the beginning of this chapter.

Although Huntsman succeeded so well that he is clearly
entitled to the credit of having invented the crucible proc-
ess, he met with many difficulties, from porosity of his
ingots mainly; this trouble was corrected largely by Heath
by the use of black oxide of manganese. Heath attempted
to keep his process secret, but it was stolen from him, and
he spent the rest of a troubled life in trying to get some
compensation from the pilferers of his process. An inter-
esting and pathetic account of his troubles will be found
in Percy.

Heath's invention was not complete, and it was finished
by the elder Mushet, who introduced in addition to the
oxide of manganese a small quantity of ferro-manganese, an
alloy of iron and manganese; and it was now possible, with
care and skill, to make a quality of steel which for uni-


formity, strength, and general utility has never been

Crucible-steel was produced then by charging into a
crucible broken blister-steel, a small quantity of oxide of
manganese, and of ferro-manganese, or Spiegel-eisen, cover-
ing the crucible with a cap, and melting the contents in a
coke-furnace, a simple furnace where the crucible was
placed on a stand of refractory material, surrounded by
coke, and fired until melted thoroughly.

The first crucibles used, and those still used largely in
Sheffield, were made of fire-clay ; a better, larger, and more
durable crucible, used in the United States exclusively,
and in Europe to some extent, is made of plumbago,
cemented by enough of fire-clay to make it strong and
tough. As the demands for steel increased and varied it
was found that the carbon could be varied by mixing
wrought iron and blister-bar, and so a great variety of
tempers was produced, from steel containing not more than
0.10$ of carbon up to steel containing 1.50$ to 2$ of
carbon, and even higher in special cases.

It was soon found that the amount of carbon in steel
could be determined by examining the fractures of cold
ingots; the fracture due to a certain quantity of carbon is
so distinct and so unchanging for that quantity that, once
known, it cannot be mistaken for any other. The ingot is
so sensitive to the quantity of carbon present that differ-
ences of .05$ may be observed, and in everyday practice
the skilled inspector will select fifteen different tempers of
ingots in steels ranging from about 50 carbon to 150 car-
bon, the mean difference in carbon from one temper to
another being only .07$. And this is no guess-work; no
chemical color determination will approach it in accuracy,



and such work can only be checked by careful analysis by

This is the steel-maker's greatest stronghold, as it is pos-
sible by this means for a careful, skilful man to furnish to
a consumer, year after year, hundreds or thousands of tons
of steel, not one piece of which shall vary in carbon more
than .05$ above or below the mean for that temper.

The word " temper" used here refers to the quantity of
carbon contained in the steel, it is the steel- maker's word;
the question, What temper is it? answered, No. 3, No. G,
or any other designation, means a fixed, definite quantity
of carbon.

When a steel-user hardens a piece of steel, and then lets
down the temper by gentle heating, and he is asked, What
temper is it ? he will answer straw, light brown, brown,
pigeon-wing, light blue, or blue, as the case may be, and he
means a fixed, definite degree of softening of the hardened

It is an unfortunate multiple meaning of a very com-
mon word, yet the uses have become so fixed that it seems
to be impossible to change them, although they sometimes
cause serious confusion.

The quantity of carbon contained in steel, and indeed of
all ingredients, as a rule, is designated in one hundredths
of one per cent; thus ten (.10) carbon means ten one hun-
dredths of one per cent; nineteen (.19) carbon means nine-
teen one hundredths of one per cent; one hundred and
thirty-five (1.35) carbon means one hundred and thirty-
five one hundredths of one per cent, and so on. So also
for contents of silicon, sulphur, phosphorus, manganese
and other usual ingredients.

This enumeration will be used in this work, and care


will be taken to use the word " temper" in such a way as
not to cause confusion.

It has been stated that crucible-cast steel is made from
ten carbon up to two hundred carbon, and that its content
of carbon can be determined by the eye, from fifty carbon
upwards, by examining the fracture of the ingots. The
limitation from fifty carbon upwards is not intended to
mean that ingots containing less than fifty carbon have no
distinctive structures due to the quantity of carbon; they
have such distinctive structures, and the difficulty in ob-
serving them is merely physical.

Ingots containing fifty carbon are so tough that they
can only be fractured by being nicked with a set deeply,
and then broken off; below about fifty carbon the ingots
are so tough that it is almost impossible to break open a
large enough fracture to enable the inspector to determine
accurately the quantity of carbon present; therefore it is
usual in these milder steels, when accuracy is required,
to resort to quick color analyses to determine the quan-
tity of carbon present. Color analyses below fifty carbon
may be fairly accurate, above fifty carbon they are worth-

As the properties and reliability of crucible-steel be-
came better known the demand increased, and the re-
quirements varied and were met by skilful manufacturers,
until, by the year 18GO, ingots were produced weighing
many tons by pouring the contents of many crucibles into
one mould ; in this way the more urgent demands were
met, but the material was very expensive and the risks in
manufacturing were great. About this time, stimulated
by the desire of enlightened governments to increase their
powers of destruction in war by the use of heavy guns of


greater power than could be obtained by the use of cast
iron, and for heavier ship-armor to be used in defence,
Mr. Bessemer, of England, now Sir Henry Bessemer, rea-
soned that if melted cast iron was reduced to wrought
iron by puddling, or boiling, by the mere oxidation, or
burning out, of the excess of carbon and silicon from
the cast iron, that the same cast iron might be reduced to
steel in large masses by blowing air through a molten mass
in a close vessel, retaining enough heat to keep the mass
molten so that the resulting steel could be poured into
ingots as large as might be desired. At about the same
time, or a little earlier, Mr. Kelly, of the United States,
devised and patented the same method. Both of these
gentlemen demonstrated the potencies of their invention,
and neither brought it to a successful issue.

To persistent and intelligent iron-masters of Sweden
must be given the credit of bringing the process of Besse-
mer to a commercial success, and so they gave to the
world pneumatic or Bessemer steel, the latter name hold-
ing, properly, as a just tribute to the inventor, and this
inaugurated the third general division :


Bessemer steel is made by pouring into a bottle-shaped
vessel lined with refractory material a mass of molten
cast iron, and then blowing air through the iron until the
carbon and silicon are burned out. The gases and flame
resulting escape from the mouth of the vessel.

The combustion of carbon and silicon produce a tem-
perature sufficient to keep the mass thoroughly melted, so


that the steel may be poured into moulds making ingots of
any desired size.

In the beginning, and for many years, the lining of the
vessel was of silicious or acid material, and it was found
that all of the phosphorus and sulphur contained in the
cast iron remained in the resulting steel, so that it was
necessary to have no more of these elements in the cast
iron than was allowable in the steel. The higher limit for
phosphorus was fixed at ten points (.10$), and that is the
recognized limit the world over. When Bessemer pig is
quoted, or sold and bought, it means always a cast iron
containing not more than ten phosphorus.

In regard to sulphur, it was found that if too much
were present the material would be red-short, so that it
could not be worked conveniently in the rolls or under the
hammer, and that when the amount of sulphur present
was not enough to produce red-shortness it was not suffi-
cient to hurt the steel.

As red-short material is costly and troublesome to the
manufacturer, it was not found necessary to fix any limit
for sulphur, because the makers could be depended upon
to keep it within working limits.

Later investigations prove this to be a fallacy, as much
as ten or even more sulphur has been found in broken
rails and shafts, the steel having made workable by a per-
centage of manganese. (See the results of Andrews's in-
vestigation given in Chap. X.)

During the operation of blowing Bessemer steel the
flame issuing from the vessel is indicative of the elimina-
tion of the elements, and it is found that while the com-
bustion is partially simultaneous the silicon is all removed
before the carbon, and the characteristic white flame


towards the end of the blow is known as the carbon flame;
when the carbon is burned out, this flame drops suddenly
and the operator knows that the blow is completed. Any
subsequent blowing would result in burning iron only.
During the blow the steel is charged heavily with oxygen,
and if this were left in the steel it would be rotten, red-
short, and worthless. This oxygen is removed largely by
the addition of a predetermined quantity of ferro-man-
ganese, usually melted previously and then poured into the

The manganese takes up the greater part of the oxygen,
leaving the steel free from red shortness and easily

The fact that the phosphorus of the iron remained in
the steel notwithstanding the active combustion and
high temperature led to the dictum that at high temper-
atures phosphorus could not be eliminated from iron.
This conclusion was credited because in some of the so-
called direct processes of making iron where the tempera-
ture was never high enough to melt steel all, or nearly all,
of the phosphorus was removed from the iron.

For many years steel-makers the world over worked
upon this basis, and devoted themselves to procuring for
their work iron containing not more than ten (.10) phos-
phorus, now universally known and quoted as Bessemer

Two young English chemists, Sidney Gilchrist Thomas
and Percy C. Gilchrist, being careful thinkers, concluded
that the question was one of chemistry and not one of
temperature; accordingly they set to work to obtain a basic
lining for the vessel and to produce a basic slag from the
blow which should retain in it the phosphorus of the


iron. After the usual routine of experiment, and against the
doubtings of the experienced, they succeeded, and produced
a steel practically free from phosphorus. For the practi-
cal working of their process it was found better, or neces-
sary, to use iron low in silicon and high in phosphorus,
using the phosphorus as a fuel to produce the high tem-
perature that is necessary instead of the silicon of the
acid process. In the acid process it is found necessary to
have high silicon two percent or more to produce the
temperature necessary to keep the steel liquid; in the
Thomas-Gilchrist process phosphorus takes the place of
silicon for this purpose.

In this way the basic Bessemer process was worked out
and became prominent.

The basic Bessemer process is of great value to England
and to the continent of Europe by enabling manufacturers
to use their native ores, which are usually too high in phos-
phorus for the acid process, so that before this invention
nearly all of the ores for making Bessemer steel were im-
ported from Sweden, Spain, and Africa.

The basic process has found little development in the
United States, because the great abundance of pure ore
keeps the acid process the cheaper, except in one or two
special localities. Where the basic process is profitable in
the United States, it is worked successfully.

At about the time that Bessemer made his invention
William Siemens, afterward Sir William, invented the well-
known regenerative gas-furnace. A Frenchman named
Martin utilized this furnace to melt steel in bulk in the
hearth of the furnace, developing what was known for
some years as Siemens-Martin steel, or open-hearth steel;
the latter name has prevailed, and open-hearth. steel is


the fourth of the general kinds of steel mentioned in the
beginning of this chapter.

At first open- hearth steel was made upon a specially
prepared sand bottom, by first melting a bath of cast iron
and then adding wrought iron to the bath until by the ad-
ditions of wrought iron and the action of the flarne the
carbon and silicon of the cast iron were reduced until the
whole became amass of molten steel. Sometimes iron ore
is used instead of wrought iron as the reducing agent; this
is called the pig and ore process. Now in general prac-
tice wrought iron, steel scrap, and iron ore are used, some-
times alone and sometimes together, as economy or special
requirements make it convenient.

It was found as in the Bessemer, so in the open -hearth,
the sulphur and the phosphorus of the charge remained
in the steel, making it necessary to see that in the charge
there was no more of these elements than the steel would

This is known now as the acid open-hearth process.

After the success of the basic Bessemer process was as-
sured the same principle was tried in the open-hearth;
a basic bottom of dolomite or of magnesite was substituted
for the acid sand bottom, and care was taken to secure a
basic slag in the bath.

Success was greater than in the Bessemer; phosphorus
was eliminated and a better article in every way was made
by this process, now used extensively over the whole civil-
ized world.

This is the basic open-hearth process.

Neither the basic Bessemer process nor the basic open-
hearth removed sulphur, so that this element must still be


kept low in the original charge, until some way shall be
found for its sure and economical elimination.

The four general divisions, then, are :

Converted or Cemented Steel.

Crucible-cast Steel.

Bessemer \ T [ Cast Steel.
( Basic }

{Aoid i
* ~ . [Cast Steel.

Little or nothing more will be said of the first kind, as it
has been so thoroughly superseded by the cast steels.
After a statement of the most patent applications and uses
of the different cast steels the discussions which follow

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