Measurement of the fatigue limit of ferromagnetic materials by a nondestructive method

Abstract

The reliability and life of machine parts and elements of structures operating under repeated loads is related to the quality of metals, particularly their~mechanical properties. To evaluate the fatigue properties of metals various tests imitating service conditions to various degrees are used. The majority of the methods are long tests of specimens to failure. Accelerated methods of determination of the fatigue limit are very approximate and also involve failure of the test specimen. The fact is that traditional methods of fatigue tests do not meet the requirements of recent years either in the area of the theory of the fatigue failure of metals [i] or in investigation of the physical nature of the micromechanisms of plastic deformation and fracture [2-4]. New criteria have been revealed which may serve as the basis for development of accelerated nondestructive methods of evaluation of the fatigue properties of materials and parts. Indirect methods of studying fatigue, including eddy current [5], have not been accepted. In our opinion the basis of them is not physical concepts common to the fatigue process.