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INTERACTION OF HIGH CYCLE FATIGUE AND CREEP IN 9%Cr‐1%Mo STEEL AT ELEVATED TEMPERATURE
Author(s) -
Vašina R.,
Lukáš P.,
Kunz L.,
Sklenička V.
Publication year - 1995
Publication title -
fatigue and fracture of engineering materials and structures
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.887
H-Index - 84
eISSN - 1460-2695
pISSN - 8756-758X
DOI - 10.1111/j.1460-2695.1995.tb00139.x
Subject(s) - creep , materials science , equiaxed crystals , stress (linguistics) , metallurgy , martensite , stress relaxation , composite material , microstructure , linguistics , philosophy
High‐cycle‐fatigue/creep experiments were performed on a 9%Cr‐1%Mo temperered marten‐site ferritic steel at 873 K in air. The stress ratio R=σ min /σ max ranged from‐1 (“pure” fatigue) to 1 (“pure” creep). The maximum stress σ max was kept constant at 240 MPa. The lifetime depends on the stress ratio R in a non‐monotonic way. In the stress ratio interval 0.6 < R < 1.0 both the creep strain rate and the lifetime are controlled by mean stress σ mass of the stress cycle. In the stress ratio interval — 1 < R < 0.2 the lifetime is controlled by the stress amplitude na. The fatigue/creep interaction occurs in between these intervals. The fatigue/creep loading induces transformation of the tempered martensite ferritic structure into an equiaxed subgrain structure. The resulting subgrain size depends strongly on the stress ratio.