• The influence of heat treatment on properties of steel for cementation

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 5 (2019), Issue 1, pg(s) 13-15

    During the injection molding procedure of plastics, the gear pumps in their work are exposed to the effect of elevated pressure and temperature. On one of these pump there has been frequent downtime due to breakage of the driven gear. Gears which were installed as standard spare parts had stood out in operation for three months. On a sample of a broken gear were perfomed laboratory examinations (metallographic examinations, hardness control on cross-section and surface of the fracture was examined). Conclusion was that it was high quench hardening of a steel of which a part is made, the most likely cause of the fracture of a standard gear. In order to extend the useful life, two test gear are made from steel for cementation 20MnCr5. By applying the appropriate parameters of thermal chemical treatment useful life of the gear is significantly extended, after which the test gears have worked for nine months from the moment of installation.



    Machines. Technologies. Materials., Vol. 12 (2018), Issue 3, pg(s) 132-135

    In this paper the laboratory tests on the selected steel for cementation 20MnCr5 was perfomed. The influence of the contact load resistance to the adhesion wear of high-temperature carbonitrided MnCr steels was analyzed. As a representative example was selected a tribosystem drive/driven gear of reducers in which are expressed high contact loads. For the purposes of these tests, the samples were first high-temperature carbonitrided, and then they are carried to the appropriate chemical and metallographic analysis, control of the surface hardnesses and the resistance to the adhesion wear. The aim of this paper was to observe the representative tribosystem as much possible to define its working parameters in order to determine the optimum conditions for testing the influence of the contact load on resistance to the adhesion wear. The analysis results show that high-temperature carbonitrided steel where the atmosphere of furnace at the beginning of carburizing was enriched with nitrogen, and finally with carbon showed significantly greater resistance to the adhesion wear compared to steel that at the beginning of carburizing had atmosphere of furnace rich in carbon, and finally with nitrogen.



    Machines. Technologies. Materials., Vol. 11 (2017), Issue 6, pg(s) 323-326

    In the production of oil in the oil mill parts of the equipment wear due to contact with seeds which contain microabrasive particles. This wear manifests itself by changing the dimensions and geometry of the screw press. The paper analyzes the influence of tribocorrosive wear on the workpieces of the screw press. The appearance of wear is most likely due to the action of aggressive media, in this case the oilseeds. In the experimental part of this paper, on samples made of cast steel and austenistic stainless steel, following laboratory tests were performed: electrochemical testing, testing of chemical composition of the base material, wear analysis, microstructure recording and hardness testing. Based on the laboratory testing, conclusion was that the austenistic stainless steels 304L and 316L with nitrated surfaces exhibit better resistance to tribo-corrosion wear in relation to cast steel GS-42CrMo4.


    Innovations, Vol. 4 (2016), Issue 2, pg(s) 39-41

    For the purposes of testing tribological characteristics of the stainless steel X20Cr13 designed for the parts of process industry plants for the production of sunflower oil, test samples were made and heat treatment by improving on different hardnesses was performed. Final machine processing of the samples was performed out by grinding and polishing. This way, the different characteristics of the surface layer and the different surface topography were achieved. The paper presents the results of the impact of the hardness on characteristics of the stainless steel X20Cr13. By examining the resistance to the adhesion wear it was concluded that the higher wear was on the test samples which have been in the raw condition and who were also loaded by higher forces. Therefore, the quality of the surface wear greatly affects the surface roughness and the coefficient of friction.