Ingots with a daisy-shaped cross section are used to make wrought-steel wheels. This appreciably complicates the deformation process and increases the likelihood that the timished product will need to be repaired or rejected. Thus, one prerequisite to improving the quality of the semifhiished products used to make wrought-steel wheels is a changeover to continuous-casting of the wheel steel. Not only is continuous-casting more economical, but the use of this technology to obtain semitimished products with a circular cross section makes it easier to produce axisymmetric shapes --especially wrought-steel wheels and tread bands.The fact that railroad wheels and tread bands are subject to increasingly severe service conditions means that these products must meet higher standards with respect to quality: the rim and tread must have sufficient strength and hardness --which determine wear resistance and contact strength --and must simultaneously have high ductility characteristics, guaranteeing strength and resistance to the growth of defects under dynamic and thermal loads. The web must first of all have a good combination of ductility and strength, thus ensuring the requisite resistance to fatigue during high-cycle shock loading. Products with these properties can be obtained through a correct choice of material and manufacturing technology, including refining and teeming of the steel, mechanical shaping, and heat treatment of the timished product. Continuous-cast semifinished products fit these needs. Continuous-cast semitimished products have been used at the Nizhnedneprovsk Pipe Plant (NPP) to make wrought-steel wheels.After a study of features of the structure of 410-ram-diam. continuous-cast wheel blanks composed of Czech-made vacuum converter steel, it was found that their surface quality is quite high. There were no visible defects of metallurgical origin that are typically seen in conventional ingots. The semitimished products were characterized by a uniform chemical composition, a small (compared to ingots) number of shrinkage and segregation defects, and a uniform and dense macrostructure (Fig. 1) except for the narrow axial region. The width of this region was one-fifth the width typically seen in ingots. The timeness of the dendritic and nondendritic grains was twice as great as in wheel ingots, the content of nonmetallic inclusions was one-quarter as great, and the metal was more ductile [1][2][3].Efficient methods were sought for the commercial production of 960-ram-diam. rolled wheels and tread bands from 410-ram-diam. continuous-cast blanks. It was discovered that there is a distinctive feature to the deformation of such blanks, due to the substantial difference in the geometric dimensions of continuous-cast semitimished products and semitimished products (blocks) obtained from ingots: the ratio of height to diameter differs by a factor of more than two. Thus, it was found that the rolling operation takes place more efficiently with the use of continuous-cast blanks that are smaller in diameter but tal...
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