METHODS OF REDUCING THE STRENGTH OF STEEL THREADED FASTENING ELEMENTS TO THE DEFORMATION AGING

Deformation aging, the ongoing processes of natural deformation aging and possible artificial deformation aging can lead to a decrease in resistance to both viscous and brittle fracture. Based on the analysis of existing methods for determining the propensity to deformation aging of steel products, the expediency of using a structural method for cold-deformed articles to reduce the propensity to aging is justified, which will also ensure an increase in the complex of mechanical characteristics without additional alloying. Methodology. As a material for this study, M12x1.75x70 bolts of strength class of 20kp steel were chosen. The structure and mechanical properties of bolts after various treatments were investigated. Findings. For steel products produced and operated in a cold-deformed state, a method is proposed that simultaneously increases the complex of their mechanical properties and practical immunity to deformation aging. Originality. A new method for reducing the propensity to deformation aging of cold-deformed steel products is proposed: fasteners obtained by cold volume stamping. This method differs from the known ones in that if in a known structural method a certain (favorable) type of dislocation structure for a given deformation effect during operation is due to a previously created certain initial structural state, then in the proposed method for steel products, in which the negative effect of deformation aging is due to a dislocation structure, formed in them by technological active cold deformation, obtaining a favorable dislocation structure up to is transformed by the transformation of the original structure due to temperature and cyclic deformation effects. Practical value. Understanding the mechanisms of structural changes and obtaining quantitative patterns describing the process of deformation aging of steel products obtained by cold deformation.