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On the Cyclic Softening Mechanisms of Reduced Activity Ferritic/Martensitic Steels
Author(s) -
Giordana Maria Florencia,
AlvarezArmas Iris,
Armas Alberto
Publication year - 2012
Publication title -
steel research international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.603
H-Index - 49
eISSN - 1869-344X
pISSN - 1611-3683
DOI - 10.1002/srin.201100254
Subject(s) - softening , materials science , martensite , metallurgy , microstructure , dislocation , ferrite (magnet) , cyclic stress , stress (linguistics) , low cycle fatigue , composite material , linguistics , philosophy
Low‐cycle fatigue tests were performed in three different ferrite/martensite steels, i.e., the European RAFM steel EUROFER 97 and the commercials AISI 410 and AISI 420, at room temperature (RT) and at 550°C. After the first few cycles, a cyclic softening that continues up to failure is observed for all these steels. The cyclic softening exhibited by AISI 420 is less pronounced than for the other two steels. The comparison between the mechanical responses of the materials was based on the study of the flow stress components, i.e., the friction and the back stresses, and their correlation with the microstructure evolution. In most cases, the strong cyclic softening observed is produced by the decreasing stress values exhibited by both stress components. However, at RT, for AISI 420, the back stress does not present variation during cycling. The decrease of the free dislocation density inside the subgrains and the growth of the mean subgrain size represent the main microstructural evolution.