The change of the coercive force under fatigue testing of 40X steel specimens

• Main Authors: Вакуленко, К. В., Казак, И. Б., Безлюдько, Г. Я., Ярещенко, В. Г., Елкина, Е. И.
• Format: Article
• Language: Russian
• Published: Інститут енергетичних машин і систем ім. А. М. Підгорного Національної академії наук України 2015
• Subjects: cyclic loading; degradation of structure; submicron fissures; coercive force; surface plastic deformation; healing of defects; УДК 620.178.32; 620.179.141; 620191.33; 539.4; 539.61; циклическое нагружение; деградация структуры; субмикротрещины; коэрцитивная сила; поверхностное пластическое деформирование; залечивание дефектов; циклічне навантаження; деградація структури; субмікротріщини; коерцитивна сила; поверхневе пластичне деформування; заліковування дефектів
• Online Access: https://journals.uran.ua/jme/article/view/46688

The influence of cyclic loading and subsequent surface plastic deformation on the change of the coercive force of normalized 40X steel specimens was studied.  It was found that after a cyclic loading of specimens their coercive force increases by 1.5–2 times throughout entire range of loads used, which indicates an increase in the degree of fatigue damage accumulation in steel structure.  In the same time, the most essential increase in the coercive force is noted at the initial phases of relative elongation (deformation) of the specimens (up to 1–1.5%). It was revealed that implementation of a surface plastic deformation of the specimens, which have undergone a preliminary cyclic loading, leads to lowering of values of coercive force and allows to raise their longevity by 2.8–3.4 times. The hypothesis was expressed that this effect is related to a healing of the submicron discontinuity flaws, formed in the material during cyclic loading.  The hypothesis is based on the concepts of the modern material science concerning a healing of defects in the conditions of hydrostatic compression, on a phenomenon of anomalous mass transfer during a pulsed action on the metal, and on a phenomenon of adhesive interaction of solids.