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the manufacture of steel.
305
ler pieces. The latter are sometimes immediately rolled out into bars, which
are then termed råstänger or rough-bars. But, if a superior, more slagless iron is
to be made, they will have to be heated anew (welded) in hearths or heating
furnaces and are thereupon either hammered into bar iron under a smallish
hammer (termed räclchammare or extending hammer), or rolled under rollers.
Pig iron to be suitable for Lancashire forging should be white or mottled
and contain: 0-2 to 0’3 % of silicon, 0’2 to 0’3 % of manganese, O’oos to O’oio %
of sulphur, 0*05 to 0’07 % of phosphorus, and 4 to 4’2B % of carbon.
The usual consumption per ton of blooms is from 25 to 35 hectoliters of
charcoal and from 1 100 to 1 150 kilograms of pig iron. The output per hearth
with two tuyeres a week is as a rule 15 or 16 tons of blooms.
The Manufacture of Blister Steel.
Manufacture of blister steel during the period from 1891 to 1913. See
Table 58.
Table 58. Output of Blister Steel in Sweden.
Annually Tons
1891—95 ...... 797
1&96-0U...... 920
1901—05 ...... 795
1906—10 ...... 410
191 1........ 436
191 2........ 425
191 3........ 196
The output, as will be seen, is very small and has been steadily
declining. In 1913 there were 3 cementation furnaces in use (2 at Österby,
1 at Svanå).
Blister steel is used chiefly as a raw material in the manufacture of
crucible steel.
The Manufacture of Steel.
By steel in contradistinction from wrought iron is signified steel and
malleable iron which when produced is obtained in a molten condition.
The preparation of ingot iron (steel) is carried out in different manners:
in Bessemer converters, in Siemens-Martin furnaces, in crucibles, and in
electric furnaces.
In Sweden the Bessemer process was first used in 1858, the Uchatii
method of crucible smelting in 1860, the Siemens-Martin process in 1868,
crucible smelting in the ordinary sense of the term in 1871 and electric
steel smelting in 1900.
The Bessemer Process. Although this process bears the name of its
inventor, Henry Bessemer, an Englishman, it may be said to be the
fruit of Swedish work. It was in Sweden and by Swedes that it was
elaborated and rendered practicable, and therefore the history of this
process will always be of very special interest to Sweden.
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