Abstract
Sulphur is said to be detrimental to pig iron. The author studied what amount of the sulphur would develop detrimental properties in practice. The result of the experiment was summarized as follows:
(1) The running property of the melt becomes worse with increase of the sulphur, and especially worse when the sulphur is more than 0·282%.
(2) When the sulphur reaches 0·282%, there appears a chill phenomenon, the shrinkage becomes maximum, and blow holes are found.
(3) The combined carbon increases abruptly at 0·282% sulphur.
(4) The graphitic carbon becomes somewhat refined and the cementite more distinct at 0·282% sulphur. The grain size of manganese sulphide is maximum at 0·282% sulphur.
(5) The tensile strength is enhanced with increase of the sulphur, but tends to be lower at around 0·282% sulphur.
(6) The transverse load and the deflection shows a tendency similar to that of the tensile strength.
(7) The hardness sharply rises at 0·282% sulphur.
(8) The tensile strength sharply rises at 0·282% sulphur.
(9) The reduction of area becomes lower at 0·282% sulphur.
(10) The impact value becomes abruptly to decrease at 0·282% sulphur.
(11) The fatigue limit gradually rises with increase of the sulphur.
(12) The wear amount becomes conspicuous at above 0·282% sulphur.
, (13) The tensile strength at elevated temperatures is lower by about 2kg/mmmm2 at 400°C than that at the normal temperature. The tendency of the strength-sulphur curve is similar to that observed at room temperature. At 800°C, the strength somewhat decreases at the sulphur content lower than 0·282%, but becomes somewhat higher at above 0·282%, the increase being about 4-5kg/mmmm2.
(14) In the growth test, the volume somewhat increases at the sulphur content below 0·186%, but tends to decrease at 0·282% sulphur. Decarburization at elevated temperatures in checked with increase of the sulphur.
(15) In the corrosion test, the effect of sulphur is not perceived excepting for sulphuric and nitric acid.
(16) Distribution and amount of the sulphur in cast iron is roughly observed with the sulphur print.
In conclusion, the greatest effect of the sulphur is hot brittleness at elevated temperatures. Although an impact test at elevated temperatures was not made, it was presumed from the tendency cutves of the impact strength at room temperatures and the tensile strength at high temperatures, that the sulphur content lower than 0·186% confers no harmful effect. Even in case such amount of the sulphur should happen to exert a very harmful effect, it would be presumed that it was not due to the sulphur per se, but rather to the oxygen (as the element congenial to sulphur) as well as to the cooling rate.