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The influence of plasma nitriding process conditions on the microstructure of coatings obtained on the substrate of selected tool steels

Mokrzycka Magdalena, Przybyło Adrianna, Góral Marek, Kościelniak Barbara, Drajewicz Marcin, Kubaszek Tadeusz, Gancarczyk Kamil, Gradzik Andrzej, Dychtoń Kamil, Poręba Marek, Jopek Jakub, Pytel Maciej

Advances in Mechanical and Materials Engineering

2024

Vol. 41, nr 1

5-16

This study presents the results of research into the influence of the time of the plasma nitriding process on the microstructure of the coatings obtained. Cold-work tool steels (60WCrV8, 90MnCrV8, 145Cr6), hot-work tool steel (X37CrMoV5-1) and high-speed tool steel (HS6-5-2) were selected as substrate material. The processes were carried out under industrial conditions using an Ionit device from Oerlikon Metaplas with variable process times of 2, 4 and 6 hours. According to literature data, a nitriding mixture consisting of 5% nitrogen and 95% hydrogen was chosen, which allowed the expected diffusion layer to be obtained without a white layer (composed of iron nitrides). Analysis of elemental mapping indicates that the presence and content of nitride-forming elements influences the formation of alloy additive nitrides in the microstructure of the diffusion layer. It was also found that an increase in the duration of plasma nitriding, results in an increase in the depth of the nitrided layers formed on the substrate of high-alloy steels: X37CrMoV5-1 and HS6-5-2. Nitrides of alloying additives, present in the diffusion layer, are formed in the high-alloyed the hot-work steel X37CrMoV5-1, indicating that these steels are the most suitable for plasma nitriding of the entire tool steels analysed.

W pracy przedstawiono wyniki badań wpływu czasu procesu azotowania plazmowego na mikrostrukturę otrzymanych powłok. Jako materiał podłoża wybrano stale narzędziowe do pracy na zimno (60WCrV8, 90MnCrV8, 145Cr6), stale narzędziowe do pracy na gorąco (X37CrMoV5-1) oraz szybkotnące (HS6-5-2). Procesy prowadzono w warunkach przemysłowych z wykorzystaniem urządzenia Ionit firmy Oerlikon Metaplas ze zmiennymi czasami procesu 2, 4 i 6 godzin. Zgodnie z danymi literaturowymi wybrano mieszaninę azotującą składającą się z 5% azotu i 95% wodoru, co pozwoliło na uzyskanie oczekiwanej warstwy dyfuzyjnej bez warstwy białej (złożonej z azotków żelaza). Analiza mapowania pierwiastkowego wskazuje, że obecność i zawartość pierwiastków azototwórczych w pływa na powstawanie azotków dodatku stopowego w mikrostrukturze warstwy dyfuzyjnej. Stwierdzono również, że wydłużenie czasu azotowania plazmowego powoduje zwiększenie głębokości warstw azotowanych powstających na podłożu ze stali wysokostopowych: X37CrMoV5-1 i HS6-5-2. Azotki dodatków stopowych, obecne w warstwie dyfuzyjnej, powstają w wysoko-stopowej stali do pracy na gorąco X37CrMoV5-1, co wskazuje, że stale te są najbardziej odpowiednie do azotowania plazmowego spośród wszystkich analizowanych stali narzędziowych.

Evaluation of Wear Mechanisms of Graphites Used for Crystallisers for Continuous Casting

Brudny Anna, Kulasa Joanna, Juszczyk Barbara, Myalski Jerzy, Roskosz Stanisław, Wycisk R., Kwaśniewski Paweł, Strzępek Paweł, Poręba Marek

Archives of Foundry Engineering

2022

Vol. 22, iss. 4

109--115

This paper presents the results of research concerning the evaluation of tribological properties of graphite materials used, among others, for crystallisers for continuous casting of non-ferrous metals and their alloys. Graphite materials differing not only in their physical properties but also in the technology of their production were selected from a wide range of commercially available products. Wear resistance investigations of the tested graphite materials were carried out on a pin-on-disc tribometer under technically dry friction conditions on a sliding distance of 1000 m. A constant load but variable speed was used in the tests. The mean value of the coefficient of friction and the wear of the material were determined based on the tribological tests carried out. It was observed that as the speed increases, the average value of the coefficient of friction decreases, while the wear increases. A microstructural analysis of the wear track showed that the friction mechanism depends mainly on the graphite formation technology, which is related to the microstructure of the tested materials, and to a lesser extent to their physical and mechanical properties. Varying the speed values made it possible to trace changes in the wear mechanism, on the basis of which it is possible to predict the durability and reliability of graphite crystalliser operation.

Influence of crystallographic orientation on creep resistance of single-crystal superalloy

Kościelniak Barbara, Gancarczyk Kamil, Poręba Marek, Albrecht Robert

Advances in Manufacturing Science and Technology

2020

Vol. 44, nr 3

93--98

This paper focuses on the influence of crystallographic orientation on creep resistance of CMSX-4 nickel-based superalloy. The single-crystal rods of CMSX-4 superalloy were manufactured with the use of the Bridgman method at a withdrawal rate of 3 mm/min. The crystallographic orientation of the rods was determined by the X-ray Ω-scan method with OD-EFG diffractometer and the Laue back-reflection technique. The creep tests were performed at a temperature of 982°C and the value of stress σ = 248 MPa. Microstructural investigation before and after the creep test of CMSX-4 superalloy was performed using a scanning electron microscope. The results showed that the distribution of the values of α angle strongly affects the creep resistance of a single-crystal superalloy