Subbotina V. Effect of residual stress state on fatigue durability of high-strength steels after surface plastic deformation.

Subject: High-strength steels after hardening, caused by superficial plastic deformation. Purpose: Identifying the principles of residual stress state forming as a result of deformation, caused by use of rollers; development of types of managing residual macro-stress state and issuance of recommendations for optimization the modes and technologies of use of rollers. Research methods: Methods used include X-ray tensometry, X-ray structural and metallographic analysis, as well as methods of identifying mechanical characteristics. Tests have been carried out in order to identify the fatigue durability both for the samples and for natural details. Theoretical and practical results: the principles of residual stress state forming as a result of deformation, caused by use of rollers, have been identified. Also, major principles of under-hardened local zones creation as a result of use of rollers have been identified and theoretically grounded. These principles decrease effectiveness of superficial plastic deformation maintenance and identify their fatigue durability. Another result is grounding the principles of choosing a technological scheme for rollers usage, which guarantees uniformity of residual stress state distribution across the overall sample surface and, consequently, the uniformity of durability of processed samples. Extent of implementation: technology of superficial plastic deformation, caused by use of rollers for high-strength steels heavy-weight samples has been improved and has been implemented at the state enterprise "Malyshev Plant" (Kharkiv city). Application field: Machine-building.