Publication:
Microstructural Evolution of Lean Duplex Stainless Steels under Different Loading Conditions

dc.contributor.advisor Escobedo-Diaz, Juan Pablo en_US
dc.contributor.advisor Asraf, Mahmud en_US
dc.contributor.advisor Bhattacharyya, Dhriti en_US
dc.contributor.author Ameri, Ali en_US
dc.date.accessioned 2022-03-15T08:28:21Z
dc.date.available 2022-03-15T08:28:21Z
dc.date.issued 2020 en_US
dc.description.abstract Lean Duplex Stainless Steels 2101 and 2404 (LDX 2101 and LDX 2404) are relatively new dual phase steel alloys with equal volume fractions of ferrite and austenite phases. Their attractive mechanical properties (high yield stress, ultimate tensile strength, and ductility), and corrosion properties make them suitable for many applications, such as offshore platforms and in the nuclear industry. Engineering components in such applications are likely to be subjected to different stress states and strain rates. However, the available literature shows a limited number of studies on the mechanical response and microstructural changes of LDX 2101 and LDX 2404. Thus, the aim of this study is understanding the mechanical response of LDX 2101 and LDX 2404 and microstructural changes in their constituent phases under uniaxial stress and uniaxial strain conditions. Compressive uniaxial stress testing at a strain rate of 10-3 s-1 showed that flow stress of both alloys is anisotropic. This anisotropy resulted from strain partitioning between the constituent phases, phase boundaries morphology, grain size, and austenite deformation mechanisms. Compressive uniaxial stress testing at different strain rates showed that LDX 2404 has a higher flow stress. LDX 2101 showed a higher working rate at 10-3 s-1 because of the martensitic transformation and subsequent mechanical twinning within the martensite. Also, increasing strain rate had a higher effect on the flow stress of LDX 2101 due to deformation localization within the hard austenite as strain rate increases. Shock-compression testing of both materials under peak stresses (9-19 GPa) showed that the reversible ferrite to martensite transformation occurs above 18 GPa, the fingerprint of this transformation is the development of {332}<113> twins. Quasi-static compressive testing of post-shocked samples showed that samples shocked above 18 GPa experience a considerable increase in their flow stresses likely because of the aforementioned reversible transformation. Examining the spall response of both material under different peak stresses and deformation histories showed that LDX 2404 has a higher spall strength because it has a higher fraction of the phase boundaries. Incipient spall damage in both materials preferentially occurred within ferrite. Spall damage varied with peak stress from quasi-cleavage fracture in the incipiently spalled samples to brittle fracture in the fully spalled samples. This study showed that the mechanical responses of LDX 2101and LDX 2404 depends on the deformation mechanisms of both constituent phases and the interactions between them in a manner that differs from classical duplex stainless steel alloys. en_US
dc.identifier.uri http://hdl.handle.net/1959.4/65357
dc.language English
dc.language.iso EN en_US
dc.publisher UNSW, Sydney en_US
dc.rights CC BY-NC-ND 3.0 en_US
dc.rights.uri https://creativecommons.org/licenses/by-nc-nd/3.0/au/ en_US
dc.subject.other Loading conditions en_US
dc.subject.other Microstructual evolution en_US
dc.subject.other Lean duplex stainless steels en_US
dc.title Microstructural Evolution of Lean Duplex Stainless Steels under Different Loading Conditions en_US
dc.type Thesis en_US
dcterms.accessRights open access
dcterms.rightsHolder Ameri, Ali
dspace.entity.type Publication en_US
unsw.accessRights.uri https://purl.org/coar/access_right/c_abf2
unsw.date.embargo 2022-03-01 en_US
unsw.description.embargoNote Embargoed until 2022-03-01
unsw.identifier.doi https://doi.org/10.26190/unsworks/2086
unsw.relation.faculty UNSW Canberra
unsw.relation.originalPublicationAffiliation Ameri, Ali, Aerospace, Civil & Mechanical Engineering, UNSW Canberra, UNSW en_US
unsw.relation.originalPublicationAffiliation Escobedo-Diaz, Juan Pablo, Aerospace, Civil & Mechanical Engineering, UNSW Canberra, UNSW en_US
unsw.relation.originalPublicationAffiliation Asraf, Mahmud, Aerospace, Civil & Mechanical Engineering, UNSW Canberra, UNSW en_US
unsw.relation.originalPublicationAffiliation Bhattacharyya, Dhriti, Faculty of Engineering, UNSW en_US
unsw.relation.school School of Engineering and Information Technology *
unsw.thesis.degreetype PhD Doctorate en_US
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