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Special alloy steel is widely used for the bearings and structural parts for the automobile, the office automation equipment and home electronics. NIPPON STEEL ENGINEERING CO.,LTD (NSEC). Started up first continuous caster for the special alloy steel in 1977. Since then, NSEC have been highly appreciated by special steel industry and have supplied the bloom continuous casters which applied a number of innovative technology to the special steel manufacturer and the integrated iron and steel manufacturer all over the world including Nippon Steel Corporation. In Japan before 1980, the special alloy steel was mainly produced by the vertical type bloom continuous caster in order to reduce the inclusions and the pinholes of bloom. However, the vertical type bloom continuous caster has many problems such as low productivity, expensive construction cost and difficult maintenance. In 1982, NSEC developed and supplied the large radius type large section bloom caster which can produce the special alloy steel for the automobile parts and the bearing, etc and can improve the productivity, the bloom internal and surface quality and the production yield. NSEC’s large radius type large section bloom caster has a number of advantages. Some of the advantages on bloom quality improvements are: （1）Reduction of the surface and internal cracks and internal inclusion thanks to Optimum Roll Profile Engineering. （2）Reduction of the surface cracks thanks to High Accuracy Mold Oscillation, Uniform Secondary Cooling and Bloom Surface Uniform Quenching. （3）Improvement of the center segregation thanks to Tundish Plasma Heater and Optimum Soft Reduction. （4）Decrease of the surface inclusions and pinholes thanks to Optimum M-EMS. （5）Decrease of the center porosity thanks to Innovative Equipment. All the above technology can be applied to new or existing bloom casters supplied not only by NSEC but also by other caster suppliers.