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Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393
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Документ Development of a combined technology for hardening the surface layer of steel 38Cr2MoAl(Технологический центр, 2017) Idan, Alaa Fadhil І; Akimov, Oleg; Kostyk, KaterynaDevelopment of new combined strengthening technologies for treatment of steel surface layer is a topical issue. Influence of conditions of combined hardening treatment on variation of properties of the surface layer of 38Cr2MoAl steel was studied. Experimental data have shown that thickness of the hardened layer of 38Cr2MoAl steel, depending on the process conditions of combined treatment, varied in the range 0.18 to 0.69 mm with the surface hardness being 10.5-12.5 GPa. Mathematical models of the hardened layer thickness and surface hardness were obtained depending on variation of velocity of the laser beam travel and duration of nitriding of steel following the combined treatment. In their structure, the models are regression equations. These regularities have practical technological significance and ensure prediction of values of the hardened layer thickness and surface hardness. Nomograms of simultaneous influence of velocity of the laser beam travel and duration of nitriding on thickness of the hardened steel layer and surface hardness were constructed. Nomograms make it possible to determine concrete conditions of hardening processing, starting from specified thickness of the hardened layer or the surface hardness of 38Cr2MoAl steel, respectively and also to solve inverse problems. This method is suitable for hardening hard-to-reach part sectios and local contact areas.Документ Development of an iron-based alloy with a high degree of shape recovery(Технологический центр, 2017) Ahmed, Sundus Mohammed; Akimov, Oleg; Kostyk, KaterynaWe examined a technological process for receiving an ironbased alloy with a shape memory effect, substantiated the choice of chemical composition of the alloy, and selected thermal treatment modes. Research results into scale resistance revealed at heating the samples in the temperature range of 600-1000 °C, surface oxidation was not observed. In the course of experiment on corrosion resistance of the alloy, we found that the alloy is corrosion resistant and is not inclined to change the weight when exposed to 10 % solution of sulfuric acid. Study into the microstructure confirmed the existence of dispersion hardening in the alloy after the aging regimes. Diffractogram of the alloy after hardening at a temperature of 1150 °C and cooling in the open air showed a surge that corresponds to γ-Fe, therefore, the content of residual austenite in the alloy is 100 %. Research results demonstrated that the degree of shape recovery of the proposed alloy is 78-97 %. The proposed alloy is plastic enough; it may undergo hot, warm and cold deformation in the open air. We constructed mathematical models of the impact of chemical composition of the alloy on tensile strength of the alloy and the values of a shape memory effect. The iron-based alloy with a shape memory effect can be obtained both under laboratory conditions and on industrial equipment.