Coercivity of Metal as a Measure of its Damage at Micro Level in Assessing Fatigue, as well as in Problems of Restoration of Mechanical Properties

摘要

Coercimetry today is the most effective method both informationally and practically (instrumentally and methodically) for assessing fatigue-type damage of metal at micro level in bench tests and during actual operation. Equally effective and useful it is in solving a specific inverse problem when attempts are made to restore the properties of fatigue-affected metal by different types of effects on it to obtain a kind of "healing" of micro fatigue accumulated in the metal. Depending on the mode of loading operation or during the tests performed recovery of desired properties in the surface layers or in the whole volume of the sample or item can be carried out. Properly executed (methodically and instrumentally) coercimetry here too very effectively monitors both qualitatively and quantitatively the degree of recovery in case of micro fatigue type degradation. On the example of cyclic mechanical bench testing of samples of alloy steel used for the manufacture of high-strength mechanical parts, 40X (C, 0.36-0.44; Si, 0.17-0.37; Mn, 0.5-0.8; Cr, 0.8-1.10), is shown such efficiency of coercimetry in assessing degradation of metal under cyclic loading in multicycle fatigue mode, as well as in various technologies of recovery of micro-level damage of metal accumulated during cyclic testing.