Dynamic strain ageing evidences during low cycle fatigue

A.F. ARMAS; M. AVALOS; I. ALVAREZ ARMAS; C. PETERSEN; R. SCHMITT

JOURNAL OF NUCLEAR MATERIALS

The Netherlands

Lugar: Elsevier; Año: 1998 vol. 258 p. 1204 - 1208

0022-3115

Abstract The in¯uence of dynamic strain ageing (DSA) on the strain cyclic behaviour of ferrite±martensite stainless steels was investigated at temperatures ranging from room temperature to 823 K. For fully annealed AISI 420 initial hardening followed by a saturation stage was observed at each test temperature. This steel was found to be susceptible to DSA as evidenced by the temperature independent stress saturation observed between 523 and 723 K. Normalized and tempered MANET II and F82H mod. softens during cyclic loading at all temperatures. In this steel DSA manifestations were observed on plotting the peak tensile stress di€erence between hysteresis loops obtained at di€erent strain rates. Strongly abnormal behaviour with higher peak tensile stresses corresponding to slower strain rates was observed in the temperature range between 500 and 700 K. It is proposed that DSA mechanisms caused by the drag of solution carbon atoms is responsible for this unusual behaviour. atoms is responsible for this unusual behaviour.