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Effects of various factors such as the grain size, the morphology of nonmetallic inclusions, and joint microalloying with boron and titanium on the high-temperature ductility of pipe steels are studied. Physical modeling of the conditions of cooling of the skin of a continuous-cast preform in the zone of secondary cooling in a Gleeble facility is performed. Technical recommendations are given for raising the hot ductility of steels under industrial conditions. Key words: hot ductility, continuous casting of steel, physical modeling, pipe steel. INTRODUCTIONReported data on carbon and alloy steels show that ductility drops in continuously cast metal occur in the temperature range of 750 -1050°C [1 -4]. When the crystallization is accompanied by additional impacts on the metal, for example, in the form of thermal or deformation cycles typical for the skin of solidified metal in the zone of secondary cooling in continuous casting machines, the temperature range of the ductility drop widens and deepens [5 -7]. It has been shown in [7,8] that ductility drops typical for the stage of cooling of steel in a continuous casting machine do not manifest themselves during subsequent hot rolling, and the studied pipe steels possess high ductility.The aim of the present work was to test the methods of grain refinement in the process of cooling of the skin of a slab in a continuous casting machine for raising the ductility of the continuously cast metal and to study the changes in the morphology of nonmetallic inclusions in heating for rolling and the effect of microalloying with boron and titanium on the ductility of steels.

Mechanical, damping and specific properties of new structural high-damping steel have been studied in the present research. Studied high-damping steel was specially produced by the JSC Severstal in order to obtain metallic material with specified level of damping and mechanical properties. Experiments show that the damping properties of industrial high-damping steel are comparable with damping properties of high-purity damping alloys, produced using laboratory equipment. Mechanical properties of the industrial high-damping steel were found to be comparable with the level of properties of well-known structural steels, widely used in the modern industry. Analysis of the combination of mechanical and specific properties of the new steel indicates that this material can be used for the construction of rigid structures requiring high damping. Specific features of practical application of high-damping steels are also discussed.

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