Refractories for continuous casting machines: Experience in the solution of problems and prospects

Abstract

At present the requirements for refractories used in continuous casting of steel are determined by economic factors. First, in the whole steel-teeming ladle-tundish-continuous casting machine mold path the steel must not be contaminated with exogenic inclusions and if possible cleansed of both exogenic and endogenic inclusions. Second, it is necessary to keep to a minimum the expenditures normally allowed for per ton of metal, and, third, for the solution of the first and second problems exclusively high-quality refractories, particularly those possessing high service reliability, are necessary.For fulfillment of any of the prospective requirements specific solutions are necessary, and a final positive result is obtained with a composite approach. The producer must introduce certain technical developments while the user must use the new refractories.It should be noted that the high requirements of the market for continuous casting machine refractories are in harmony with pricing factors. For example, in the cost of a continuously cast billet the share due to refractories providing reliable service of the continuous casting machine is 15% [1].Only rigid control over observation of the production operation in all stages of production of refractory parts for continuous casting machines (tubes, stopper monoblocks, submerged nozzles, tundish nozzles, partitions, etc.) from incoming inspection of the raw material to certification of the finished product may guarantee its stable service properties.Conclusions from analysis of the actual quality indices of a number of continuous casting machine refractory parts (physieoehemical properties) [2] made with use of a method developed in Saint Petersburg Refractory Institute agreed with the opinion of the users. Hydrostatically formed parts produced by Bogdanovich Refractory Plant were the most reliable. The authors of [2] showed that systems statistical processing of product certification data at the disposal of the producer makes it possible to evaluate the quality of highly critical refractories from the point of view of service reliability.Previously unknown possibilities of revealing infringements of the method of production and reducing the risk of the user of obtaining refractories with hidden defects are provided by use of x-ray inspection of continuous casting machine parts [3]. During introduction of production equipment for x-ray inspection of parts at Novomoskovsk Refractory Plant the Refractory Institute confirmed the possibility of revealing hidden defects of various origins, including cracks, foreign inclusions, breakdowns in the configuration of channels and variations in wall thickness of tubular parts, nonuniform areas in parts as a result of poor mixing of the mixture. Unquestionably, continuous casting machine refractories must be 100% x-ray inspected in refractory plants similarly to the inspection method used abroad [4, 5].As in the rest of the world, the necessity of production to individual requirements of the customer is becoming ever more pressing. ...