THE ROLE OF DIFFERENT METHODS OF SURFACE TREATMENT IN IMPROVING THE FATIGUE DURABILITY OF PRODUCTS
Journal Title: Вестник Харьковского национального автомобильно-дорожного университета - Year 2018, Vol 82, Issue
Abstract
Problem. Operational properties of machine parts and their joints, and first of all fatigue strength, determine the reliability and durability of their basic functions. Statistics show that over 80% of failures arise as the result of destruction due to metal fatigue processes. As you know, fatigue destruction begins in the surface, so its state plays a prominent role in the development of processes of fatigue, in the nature, place and time of the appearance of the fatigue crack and its development. The purpose of the work is to increase the resistance of fatigue and durability of machine parts due to various surface-action methods. For its solution, studies of the influence of various variants of combined methods of mechanical processing, cementation and defamation on the surface condition, as well as the modern method of bombarding the surface layer with low-energy ions have been carried out. The study of the issue of increasing fatigue strength is particularly important for large-sized and heavy-duty products made of high-strength steels, because at high static strength the probability of fatigue failure increases. It is established that after grinding the surface before cementation, and not after, the endurance limit (σ-1) of steel 20Х2Н4А increases by 41%, since compressive stresses during cementation reduce the effect of harmful stresses that occur during grinding. An even greater increase in σ-1 is achieved after the final blast-furnace treatment due to additional compressive stresses and a significant smoothing of the surface under slander. High efficiency of ionic bombardment of the surface is shown, as a result of which the grain is very ground in the thin surface layer (from 50 μm to 600 nm), the rusted substructure is frozen, defects are rectified (depressions, pores, risks, microcracks) and the surface roughness is significantly reduced. These changes to the surface contributed to a significant increase in durability of products
Authors and Affiliations
I. V. Doshchechkina, V. R. Semenchuk
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