This paper is focused on the evaluation of formability of heat resistant steel type 9Cr-1Mo by laboratory numerical simulationhot compression test confirmed by laboratory hot compression test. The 9Cr-1Mo steel represents modern 9%Cr tempered martensitic steel for high temperature applications in advanced thermal power plants. Numerical simulations were computed in software Deform 3D for five proposed sample shapes. On the base of normalized Cockcroft-Latham criterion (nCL), indicating the material damage during deformation, the sample type "tapered roller with four axial notches" was found to be the most suitable for hot workability evaluation. On base of simulations, it is also evaluated the temperature range of the workability of 9Cr-1Mo. The interval of good workability according to the nCL criteria is in the temperature range from 650 to 950 °C.

Steel 7CrMoVTiB10-10 is a Cr-Mo medium alloy steel with addition of vanadium and titanium as microalloying elements and with further addition of boron. The resulting microstructure after the heat treatment takes the form of a tempered bainite. In hot rolling of seamless tubes using this particular steel grade, it is very important to find the optimum heat treatment parameters in order to obtain the final mechanical properties according to STN EN 10216-2+A2. In this paper, various optimization concepts regarding temperature and time of tempering are being presented. Results obtained were utilized in production of seamless steel tubes in Železiarne Podbrezová.

Steel grade 14MoV6-3 is a low-carbon microalloyed steel with addition of chromium and molybdenum. This medium-strength steel exhibits a ferritic-bainitic microstructure after the heat treatment. This grade is designed mainly for power industry applications, withstanding operating temperatures up to 580 °C; in Železiarne Podbrezová, this particular grade is used for production of hot rolled seamless boiler tubes. In this paper we present the basic chemical concept of 14MoV6-3 steel along with its mechanical properties after the heat treatment. Further, analysis of the final microstructure, carbide phases and precipitation of vanadium is being presented as well. For this purpose, the yield stress theory has been proposed along with predictive nomograms for selected ferritic-bainitic phases. According to the results of DTA analyses, necessary conditions for heat treatment after rolling have been proposed. Finally, CCT diagrams for required ferritic-bainitic structure are presented as well.

Along with technologies development rise demands on the technical level of new machinery and equipment and also the reliability and efficiency of tools used in the production processes. One of the options for increasing tool life and wear resistance is the use of tools surface treatment technology called as CVD (chemical vapor deposition) and PVD (Physical Vapor Deposition) process. Chemical vapor deposition is a widely used materials-processing. CVD is an atomistic surface modification process, where a thin solid coating is deposited on an underlying heated substrate via a chemical reaction from the vapor or gas phase, PVD process is atomistic deposition process in which material is vaporized from a solid or liquid source in the form of atoms or molecules, transported in the form of a vapor through a vacuum or low pressure gaseous (or plasma) environment to the substrate where it condenses. The paper introduces the possibilities of application of these processes for cold forming tools used at operating conditions of Železiarne Podbrezová, a.s. Tools (formers and straightening rolls) are evaluated in terms of CVD and PVD coating thickness, microstructure and microhardness of tool material and coating.

In the micro-hardness range of the load, the measurement is complicated by the occurrence of the Indentation Size Effect (ISE) – the measured value of the micro-hardness is affected by the value of the applied load. The paper aims to study the influence of the automatic testers on the character type and size of the ISE. Ten testers and five standard reference blocks were involved in the “round-robin test”. Parameters of the ISE were evaluated using Meyer’s, Hays–Kendall, and PSR methods and also by statistical methods (ANOVA, t-test, regression, and cluster analysis). Despite the assumptions, a statistically significant impact of the hardness tester was found not only on the measured value but also on the character and size of ISE.