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Постійне посилання на розділhttps://repository.kpi.kharkov.ua/handle/KhPI-Press/35393
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Документ Surface hardening of steel parts(Одеський національний політехнічний університет, 2017) Idan, Alaa Fadhil І; Akimov, O. V.; Kostyk, K. O.Development of new resource-saving and costeffective technologies of combined hardening of steel parts with a significant reduction of the process duration is an important and urgent task. Aim: The aim of the work is to create a technology for combined toughening of steel parts to provide high operational properties of the steel surface layer by intensifying the nitriding process through the laser pre-treatment of steel products. Materials and Methods: Materials for study are types of steels 40, 40Cr and 38Cr2MoAl. Laser treatment of steel was performed at the LATUS-31 installation. Nitriding carried out in the environment of fine nitrogen-containing substance with activators at a temperature of 530…560 ºC during 2…3 hours. The nitriding process was carried out in the closed atmosphere in the chamber furnace without application of the protective atmospheres. Influence of laser pre-treatment and final nitriding on structure, thickness, phase structure, microhardness of surface layers of steel samples has been investigated. Results: It is shown that preliminary hardening by laser increases surface hardness in 0.88…1.15 times after nitriding, depending on brand of steel and speed of a laser beam movement, in comparison with steel nitriding in similar conditions. The combined treatment promotes significant increase in the strengthened layer – up to 0.49 mm for 40 steel type, up to 0.55 mm for 40Cr steel type and up to 0.65 mm for 38Cr2MoAl steel type.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.