Anisotropic intergranular damage development and fracture in a 14Cr ferritic ODS steel under high-temperature tension and creep

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:722

Article

Salmon-Legagneur, H.^1,2,3,4  Vincent, S.^1,5  Gamier, J.¹  Gourgues-Lorenzon, A. F.²  Andrieu, E.³ 

[1] CEA Saclay, DEN, DANS, DMN,SRMA, F-91191 Gif Sur Yvette, France

[2] PSL Res Univ, MINES ParisTech, Ctr Mat, CNRS,UMR 7633, BP87, F-91003 Evry, France

[3] ENSIACET, CIRIMAT, 4 Allee Emile Monso,BP44362, F-31030 Toulouse, France

[4] Res & Dev Automot Applicat ArcelorMittal Montatai, BP 30109,1 Route St Leu, F-60761 Montataire, France

[5] CEN Cadarache, DEN, CAD, DTN,STCP,LCIT, Bat 204,P109, F-13108 St Paul Les Durance, France

关键词: Oxide dispersion strengthened ferritic steels;    Tension;    Creep;    Intergranular damage;   

DOI  :  10.1016/j.msea.2018.02.102

来源: Elsevier

【 摘 要 】

This work addresses damage mechanisms at high temperature of a hot extruded 14Cr oxide dispersion strengthened steel rod, in particular, anisotropy induced by its strong morphological and crystallographic texture. Under uniaxial tension, intergranular damage and unstable fracture increased with test temperature; they appeared much easier along the rod axis than perpendicular to it. Creep fracture of smooth specimens involved crack initiation from the side surfaces and intergranular crack propagation, accompanied by intergranular damage. In order to get rid of fracture surface oxidation by the air environment, a methodology promoting crack nucleation from inside the specimen was built. From tensile and creep tests on notched specimens the fracture initiation location and fracture stability were first mapped as a function of test temperature, maximal stress triaxiality and loading direction. Then, for the first time to the authors' knowledge, interrupted tests on notched tensile and creep specimens, followed by low-temperature fracture allowed revealing fracture surfaces formed at high temperature, but unconnected to the external environment. Intergranular fracture and grain boundary grooving were evidenced there, together with strong chemical reactivity at the surface of internal cavities during damage development at high temperature.

【 授权许可】

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