Micromechanics and microstructure evolution during in situ uniaxial tensile loading of TRIP-assisted duplex stainless steels

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2018-09, Vol.734, p.281-290
• Main Authors: Tian, Ye, Lin, Sen, Ko, J.Y. Peter, Lienert, Ulrich, Borgenstam, Annika, Hedström, Peter
• Format: Article
• Language: English
• Subjects: Austenite; Austenitic stainless steels; Austenitic transformations; Crystal structure; Deformation; Deformation-induced martensite; Dependence; Duplex stainless steel; Duplex stainless steels; Edge dislocations; Elastoplasticity; High strength steel; in situ tensile loading; In-situ tensile; Load partitioning; Load transfer; Loading; Martensite; Martensitic stainless steels; Martensitic transformations; Micro-structure evolutions; Micromechanics; Microstructural evolution; Microstructural features; Microstructure; Plasticity; Scanning electron microscopy; Shear bands; Stainless steel; Strain hardening; Structural stability; Synchrotron radiation; Synchrotron x ray diffraction; Tensile strength; Tensile stress; Transformation induced plasticity; TRIP steels; TRIP-assisted steel; TRIP-assisted steels; X ray diffraction
• ISSN: 0921-5093; 1873-4936; 1873-4936
• DOI: 10.1016/j.msea.2018.07.040

Transformation-induced plasticity (TRIP) assisted duplex stainless steels, with three different stabilities of the austenite phase, were investigated by synchrotron x-ray diffraction characterization during in situ uniaxial tensile loading. The micromechanics and the deformation-induced martensitic transformation (DIMT) in the bulk of the steels were investigated in situ. Furthermore, scanning electron microscopy supplemented the in situ analysis by providing information about the microstructure of annealed and deformed specimens. The dependence of deformation structure on austenite stability is similar to that of single-phase austenitic steels with shear bands and bcc-martensite (α′) generally observed, and blocky α′ is only frequent when the austenite stability is low. These microstructural features, i.e. defect structure and deformation-induced martensite, are correlated with the micro- and macro-mechanics of the steels with elastoplastic load transfer from the weaker phases to the stronger α′, in particular this occurs close to the point of maximum rate of α′ formation. A clear strain-hardening effect from α′ is seen in the most unstable austenite leading to a pronounced TRIP effect.