Large Hollow Castings of Quasi-Monolithic Reinforced Steel

Abstract

To satisfy the current needs of industrial technology, it is often necessary to produce larger and larger steel products. Examples of large single components are the multiton rolls of the “5000” mill, turbine rotors used in nuclear power plants, and large engine shafts. And the forged shaft of a low-speed turbine rotor (1,530 rpm) used in a nuclear power plant with a capacity of 2 million KW is fabricated from a casting weighing between 400 and 500 tons. Thus, the problem of producing steel with a low content of nonmetallic inclusions and detrimental impurities that is more homogeneous is of great importance. As more new techniques of steel desulfurization, dephosphorization, reduction, and degassing have appeared, metallurgists now have the possibility of producing clean molten steel. The main problem is that forging large castings only partly eliminates casting defects. Also, larger forgings retain more casting defects, which are detrimental to the service characteristics of the product.