MRP - Material Refining Process

As the traditional form of melting technology, the arc furnace constitutes the basis for the high quality steel produced at C. Grossmann. This method offers the option of using scrap to produce high-grade steel for a wide range of applications or as the primary material for refinement in the MRP converter. The interaction of the metallurgical possibilities of the arc furnace with the refinement in the converter is almost perfect for the production of steels subject to special requirements. During the process, the steel reduced in phosphorous contents prepared in the electric arc, is transferred for further processing into the converter. The refining process for reducing carbon and gases is initiated with the aid of oxygen injected via jets in the floor. In the subsequent refining process with argon flushing, the steel is purified and desulphurised by adding lime.

The MRP converter is essential for low carbon qualities (C 0.02%) in the high-alloy industry. Furthermore, the sulphur contents are 0.01% in the LBO, as opposed to 0.002% in the MRP converter. This value is extremely important for improving the toughness and particularly the low temperature properties of a steel. As such, the MRP converter is almost predestined for the production of high-strength fine-grained tempering steels with good welding properties. The high-strength fine-grained steels CEGRO Grade III and CEGRO Grade IV developed by Grossmann are particularly worth mentioning here. They are melted as MRP steel and were the basis for the acceptance as G22NiMoCr5-6 into the engineering standards. The converter has proven its worth in the case of the material G32NiCrMO6-4 also developed by Grossmann for running gears (chain links, guiding wheels and drive wheels) used in large crawler excavators. These machines are frequently used in cold regions, in which the material has proven its positive properties. In addition to being extremely tough even at low temperatures, the material also guarantees outstanding surface hardenability using the inductive and flame-hardening techniques. The tendency to cracking is significantly diminished as a result of using the converter.