The authors present in this paper the experimental results and conclusions obtained after conducting a comparative study on three samples of forged semi-finished products from the steel brands 10CrMo9-10, 25CrMo4, and 42CrMo4. These are common heat-resistant alloy steels used in various industries nationally and internationally. This study aimed to test under the same identical experimental conditions of forging and heat treatment of three samples made of three different brands of steels 10CrMo9-10, 25CrMo4, and 42CrMo4. Analyzing the experimental results obtained, it can be seen for which of the three brands of tested steels the best forging and heat treatment parameters are obtained. Following experimental research, the best material was determined by analyzing the results obtained for the mechanical characteristics (tensile tests according to DNVGL-RP0034-SFC2 and NACE MR0175–hardness 207-235 HBW) and austenitic grain size. The authors determined that among the three types of steels analyzed, 10CrMo9-10 best meets the imposed requirements. This statement is in view of the comparative analysis of the results of experimental research.

In an integrated steel flow, the costs related to the consumption of metallurgical coke represent approx. 25% of the production cost of the shards obtained by continuous casting. As the price of coal returns to about 50% of that of coke, the technology of insufflating coal dust at the blast furnaces mouths, which transfers the coking process to the blast furnace, can reduce the cost of slag by 4-5%. It cannot be used to blow into the furnace any type of coal. The coal used must meet certain requirements, based on its physical and chemical properties. By thermo-derivatographic analysis, important properties of coals can be established. The authors present in this paper the results of thermal derivatographic analyzes performed on certain types of coal.