1966 Volume 52 Issue 2 Pages 120-139
The authors have studied the practical aspects of the D. M. Converter for the production of low sulphur steels containing decreased sulphur of under 0.010% by the duplex method with L. D. Converter, and compared these steels of extra low sulphur content with those of normal sulphur content by the ordinary L. D. Converter process.
Test results are summarized as follows.
(1) It is easy to desulphurize the molten steelmaking pig iron (even of comparatively low temperature) to the low sulphur pig iron of under 0.010% by use of the D. M. Converter in two or three minutes' mixing treatment with suitable eccentricity, number of revolutions, inner diameter of the ladle, and with suitable time cycle of clockwise revolution, halt, and counter-clockwise revolution given to the ladle alternately; using calcium carbide of under 1.0wt% as a desulphurizing agent.
(2) It is also technically possible to desulphurize the whole molten steelmaking pig iron from blast furnace to the low sulphur pig iron and to produce the corresponding quantity of low sulphur steels of under 0.010%S by the duplex method with L. D. Converter.
(3) The merit of desulphurizing normal sulphur steels to low sulphur steels of under 0.010%S is not always clear, but the low sulphur steels (JIS SM50 grade) have proved the marked improvement of notch impact toughness and of plastic deformation characteristics, being probably caused by the remarkable decrease of amount of sulphide inclusions.
(4) It is possible to apply desulphurizing process with the D. M. Converter widely, which proved the profitable means for the production of each low sulphur high grade of steels. Desulphurization by the D. M. Converter does not result in variation of other elemental contents. It is supposed that the low sulphur steels of under 0.010%S should become more and more needed in the fields of production of each low cost high grade special steel (of heat treating type) and of quality improvement in the products requiring much less sulphur segregation in future.
