Tool steels are used in technological processes of forming and cutting and as cutting tools due to their good mechanical properties. During their working cycle, steels are exposed to several aggressive conditions, such as thermal stress, fatigue and various forms of wear. In this article, the selected 90MnCrV8 tool steel slid against the Si3N4 testing ceramic bearing ball. All measurements were performed on a universal tribometric device UMT TriboLab (TA Instruments, New Castle, Delaware, USA) under dry conditions. The main objective of the performed experiments was to analyse the frictional properties and compare the wear of the 90MnCrV8 tested tool steel in contact with the 6.35 mm diameter ceramic ball at different friction speeds. In this measurement evaluation, the authors of the article mainly focused on the influence of the magnitude of the peripheral speed on the wear change and coefficient of friction. Further analysis was focused on the change of surface roughness of the counterpart ceramic balls as well as of the tested tool steel samples. Experimental results show the fact that tested tool steels, which can also be considered as high strength steels, can also successfully represent wear-resistant steels. It has been shown experimentally that increasing the friction speed also leads to significant degradation of the material on the sample surface. Finally, the effect of hardness on wear has also been experimentally demonstrated. The Si3N4 ceramic ball with its high strength also behaves like an abrasive, thus increasing the wear rate on the experimental tool steel samples.

The paper deals with the change in mechanical properties and wear of 90MnCrV8 universal tool steel after plasma nitriding, which is widely used to produce cutting tools with good durability and low operating costs. Plasma nitriding was performed at a temperature of 500 °C for 10 hour period in a standard N2 /H2 atmosphere with 1:3 gases ratio. Microstructure, phase structure, thickness of a nitriding layer and surface roughness of samples were measured with optical microscopes and a profilemeter. Verification of a chemical composition was carried out on the BAS TASMAN Q4 device. Wear resistance was measured on a universal TRIBOLAB UTM 3 tribometer, through a "pin on disc" method. The results of experiments have shown that plasma nitriding process, significantly improves the mechanical and tribological properties of selected materials.

This paper deals with the effect of selected cutting parameter values in machining of OCHN3MFA steel on AFM and SEM microstructural analysis, cutting forces, nanohardness, 2D and 3D surface roughness, and material removal rate of surface layers after machining. OCHN3MFA steel was selected and used to perform experiments. Firstly, the selected steel was investigated before machining tests, due to the checking of the initial microstructure and chemical composition. The microstructure was performed on the Tescan Vega TS 5135 scanning electron microscope (SEM) with the X-ray microanalyzer Noran Six/300, and the Oxford Instruments MFP-3D Infinity atomic force microscope (AFM). Chemical composition was analyzed on Tasman Q4 surface analyzer. All machining tests of the used samples were performed under the selected cutting parameters in the SU 50A lathe machine tool with the CNMG 120408-M5 cementite carbide cutting insert clamped in the suitable DCLNR 2525M12-M cutting tool holder. During the machining process of testing samples, individual components of cutting forces were measured on a Kistler 9257B piezoelectric dynamometer with their subsequent evaluation using software Dynoware. Other experiments following the machining process were performed, evaluating the effect of selected cutting parameters on surface hardening. Surface hardening after machining of testing samples was subsequently measured on Hysitron TI950 Triboindenter with a Cube Corner measuring tip and evaluated by software Triboscan. 2D and 3D surface roughness and material removal rate (MRR) were finally performed on Talysurf CCI Lite and evaluated by software TalyMap Platinum.

Analysis of the high temperature plastic behavior of high-strength steel X153CrMoV12 was developed in the temperature range of 800–1200 °C and the deformation rate in the range of 0.001–10 s−1 to the maximum value of the true strain 0.9%. Microstructural changes were observed using light optical microscopy (LOM) as well as atomic force microscopy (AFM). The effect of hot deformation temperature on true stress, peak stress and true strain was evaluated from the respective flow curves. Based on these results, steel transformation was discussed from the dynamic recovery and recrystallization point of view. Furthermore, a present model, taking into account the Zener–Hollomon parameter, was developed to predict the true stress and strain over a wide range of temperatures and strain rates. Using constitutive equations, material parameters and activation energy were derived, which can be subsequently applied to other models related to hot deformation behavior of selected tool steels. The experimental data were compassed to the ones obtained by the predictive model with the correlation coefficient R = 0.98267. These results demonstrate an appropriate applicability of the model for experimental materials in hot deformation applications.

Tool steels are used in stamping, shearing processes, and as cutting tools due to their good mechanical properties. During their working cycle, steels are subject to aggressive conditions such as heat stress, fatigue, and wear. In this paper, three tool steels, namely X153CrMoV12, X37CrMoV5-1, and X45NiCrMo4 were selected against two types of bearing balls, ZrO2 and X46Cr1. All measurements were performed on a UMT TriboLab universal tribometric instrument under dry conditions. The main objective of the experiment was to analyze and compare tool steel wear in contact with two kinds of bearing balls with a diameter of 4.76 mm. This evaluation is focused on the hardness, surface roughness, and microstructure of all samples and on the impact of the input parameters on the resulting wear. All three types of tool steels were measured in the basic annealed state and, subsequently, in the state after hardening and tempering. Experimental results show that tool steels, belonging to high strength steels, can successfully represent wear resistant steels. The content of carbide elements, their size, and shape in the microstructure play an important role in the friction process and subsequent wear. Three types of loads were used and compared in the experiments 30, 60, and 90 N. Increasing the load results in significant degradation of the material on the sample surface. Lastly, the impact of hardness and roughness of materials on wear has also been proven. If abrasive wear occurs in the friction process, there is a greater degree of wear than that of adhesive wear. This is due to less abrasive particles, which behave like a cutting wedge and are subject to subsequent deformation strengthening due to the load increase, which adversely affects the further friction process. Analysis of the results showed that the ZrO2 ceramic ball showed significantly better wear values when compared to the X46Cr13 stainless steel ball. It also improves the values of the coefficient of friction with respect to the type of wear that occurs when the experimental materials and counterparts are in contact.

This paper deals with the comparison of two tool steels M390 and M398 produced by powder metallurgy of the MICROCLEAN type. The primary use of steel is in the plastics industry to produce screws for injection molding machines. The main purpose of the paper is to analyze the hardness after different stages of heat treatment. The first part of the article evaluates the hardness of steels after hardening, which was performed using a hardening dilatometer DIL805A. A total of 8 different controlled cooling measurements were performed, for both types of powdered tool steels, from a maximum rate of 100 °C/s to a minimum of 0.01 ° C/s. Based on the results of the first set of samples from the hardening dilatometer, the optimal cooling time is evaluated to achieve the highest hardness of both materials. This rate was used to heat treat a second set of samples that had undergone a quenching process from which a selected group was quenched to -78 °C. Freezing was performed to reduce the amount of residual austenite. Before measuring the hardness, the samples were tempered at temperatures of 200, 400, 600 °C for 2x2h. The measured hardness values were then compared with data from the manufacturer BÖHLER.

The paper deals with the effect of temperature and strain rate to microstructure evolution and final hardness of 33NiCrMoV15 steel after the simulation of the deformation process on real samples using of dilatometer DIL805D. The main goal of the simulation is the evaluation of Peak Stress – deformation resistance for different deformation temperatures and rates. Measured values are also processed by regression analysis to define the mathematical model of the monitored dependency. Examined steel is high strength middle alloyed steel with an optimal level of plastic properties used for high loaded parts including howitzers and tanks gun barrels.

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