A new process for production of corrosion-resistant steels provides for refining of the high-alloy semifinished product produced in electrical furnaces in a converter with bottom blowing. Before pouring into the converter, solid metal additions in a quantity of 10-12% of the weight of the heat are added to the semifinished product.The refining is done by blowing the metal bath with gaseous mixtures with different oxidation potentials, which leads to alternation of oxidation and reduction service conditions of the lining. To correct the slag conditions of the heat, lime and fluorspar are added to the converter bath.The gas--oxygen refining (GOR) process is conducted in a converter with a detachable bottom in the center portion of which are located "tube in tube" telescopic tuyeres for supplying gases to the molten metal.In oxidation periods I and II of the heat the metal bath is blown with oxygen with a protective (natural) gas and with a mixture of oxygen and a neutral gas, respectively, and in period III, the reducing period, with only neutral gas.The converter has the form and dimensions normal for similar 60 ton converters. Its walls are lined with fired periclase--chromite parts and the bottom with unfired periclase--carbon ones.Testing in the converter lining of periclase--chromite parts of sintered periclase powder and chromium ore showed their insufficient wear resistance (not more than 53 heats), which was responsible for the use of PShPKh parts made of expensive and scarce fused materials, periclase--chromite, chrome-alumina spinel, and periclase. Under similar service conditions PShPKh parts provide a converter life of up to 80 heats but their use has a significant influence on the economic indices of the process as the result of their high cost.During service of the lining the slag belt, the life of which limits the length of a campaign, is subjected to especially intense wear.The basic failure factors acting on the lining of a GOR converter are the high temperature of the process (up to 1700-1720~ the alternating oxidation--reduction character of the gaseous atmosphere and the molten slag, the aggressiveness of the slag, the unjustifiably long time of contact of the lining with the slag in period III, and the long interheat downtimes.With positive test results in the lining of a GOR converter of PShPKh parts the question of replacement of them with refracturies equivalent in wear resistance but less expensive made of not so scarce and expensive original materials remains a pressing one.

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At present in the developed capitalist countries 75% of all corrosion-resistant steel is melted by the argon-oxygen decarburization process [i]. Metal of significantly higher quality, particularly steel with a low carbon content (less than 0.03%), than in arc electric melting furnaces is obtained by this process.In addition special original charge materials are not required and the heat is melted with a normal charge.The service conditions of the refractories in different portions of the lining of an argon-oxygen decarburization vessel differ significantly from the service conditions of refractories in converters with top blowing.The zone of maximum heating of the metal in argon-oxygen decarburization vessels is moved close to the bottom, the bath is agitated more intensely, and the temperature of the tuyere zone lining changes very rapidly.At the same time the temperature of the throat and the top of the cylindrical portion is lower [2][3][4][5].Abroad the specific service conditions of refractories in different zones of an argonoxygen decarburization vessel made it necessary to line the vessel differentially both in form of refractories used and in thickness.In particular the cylindrical portion and the bottom are made of direct-bonded periclase-chromite parts and the zones near the tuyere of materials based on previously synthesized spinel [6][7][8].Normally the throat lining does not cause a problem.As a rule it is made of the same parts as the cylindrical portion or of less expensive periclase-chromite parts. Sometimes the throat lining is made of refractories with a high AI203 content, especially in small capacity vessels [9]. In certain campaigns the life of such a lining reaches i00 heats [6][7][8].Since the 80's a tendency has been observed in World practice toward use for the lining of argon-oxygen decarburization vessels of primarily of highly burnt lime-periclase and periclase-lime refractories with a direct bond made of high-purity dolomites [I0]. As foreign experience (USA, West Germany) shows, a vessel lining made of such refractories provides a campaign length without intermediate repair at the 110-120 heat level with a maximum life of 134 heats [ii]. Domestic experience in use in the lining of a semi-production argon--oxygen refining vessel of different forms is limited primarily to parts of magnesia-spinellide composition, including those made of fused materials [12,13].In domestic industry corrosion-resistant types of steels were first produced in converters by the gas-oxygen refining method in Dnepropetrovsk Special Steel Plant in June 1987.Initially the lining of the gas-oxygen refining vessel was made of chromite--periclase refractories with use of periclase-carbon refractories in the zones of the bottom lining near the tuyeres.The reinforcing layer of the lining of the housing and the bottom is made of type KhP parts laid on edge (115 mm) and the working layer of the housing of type KhPKK parts in two bonded rows (230 + 460 mm) and in a single row in the upper tapered portion of the vessel.