SOME ASPECTS OF INFLUENCE EXERTED BY LARGE-SCALE EFFECT NATURE AT CYCLIC TESTS ON OPERATION AND RELIABILITY OF ALUMINUM ALLOY PRODUCTS

The article describes a study into the large-scale effect and properties of surface layers of solids in case of the Al–Mg system (AMg2) aluminum alloy. It demonstrates the dependence of surface layer properties on the absolute sizes of bodies. The conclusions obtained can be extended to studying the influence of different shapes of solids on their surface and linear bulk properties. New technology development and technological advance constantly toughen metal consumption requirements of engineering devices thus making it rather difficult to avoid fatigue striations and cracks forming in critical parts. In certain cases they may form at the earliest stages of operation, i.e. parts run with cracks most of their life cycle. Therefore, comprehensive assessment of their performance and life requires reliable data on the evolution of cyclic strength and durability parameters, and maximum information on the process of damage accumulation at all stages of fatigue loading: stages of crack origin and development leading to structural failure. Therefore, the need to improve the methods of fatigue testing and failure pattern detection is one of the most relevant problems of technical advance. It is established that the difference in deformation at a surface leads to changes in work-hardenability that involves changes in surface damageability and strength performance of samples. An approach to the large-scale effect as a phenomenon is considered from the perspective of the difference in surface layer plastic deformation for samples of different absolute sizes.