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.

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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 presents the influence of CAD modelling and CAM simulation advanced techniques for hard milling technology. The main aim of simulations is the ability and importance to improve and optimize hard milling process even before the real production of its own products, because their manufacturing process is rather expensive. The reached results present us roughing and finishing process of hard milling and milling strategy or generation of tool-paths in CATIA V5. All simulations of milling experiments show that the proposed clear-up tool path works well in the real cutting process and can improve the machining efficiency of the machining process. At the same time, the manufacturing must have the advanced process equipment and method due to the requirements of the design performance and machining efficiency. Finally, hard milling simulations in CAD/CAM system CATIA V5 were performed in order to determine and evaluation of suitability of the proposed shapes of the hard milling product.

This study investigated the possibility of nitride NiTi instruments using low-temperature plasma nitriding technology in a standard industrial device. Changes in the properties and fatigue life of used NiTi instruments before and after low-temperature nitriding application were investigated and compared. Nontreated and two series of plasma-nitrided NiTi instruments, designed by Mtwo company with tip sizes of 10/.04 taper, 15/.05 taper, and 20/.06 taper, were experimentally tested in this study. All these instruments were used and discarded from clinical use. The instruments were tested in an artificial canal made of stainless steel with an inner diameter of 1.5 mm, a 60° angle of curvature, and a radius of curvature of 3 mm. A low-temperature plasma nitriding process was used for the surface treatment of dental files using two different processes: 550 °C for 20 h, and 470 °C for 4 h. The results proved that it is possible to nitride dental instruments made of NiTi with a low-temperature plasma nitriding process. Promising results were achieved in trial testing by NiTi instruments nitrided at a higher temperature. Plasma-nitrided files were found to have, in some cases, significantly higher values than nontreated files in terms of fatigue life. The results showed that the nitriding process offers promising possibilities for suitably modified surface properties and quality of surface layer of NiTi instruments. Within the limitations of the present study, the cyclic fatigue life of plasma-nitrided NiTi dental files can be increased using this surface technology.

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.