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Title: Bauschinger effect in macro and micro sized high strength low alloy pipeline steels
Author: Pereira, Thiago Soares
ISNI:       0000 0004 6063 0397
Awarding Body: University of Birmingham
Current Institution: University of Birmingham
Date of Award: 2017
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The Bauschinger effects in X70, X80 and X100 high strength low alloy pipeline steels were presented. The microstructure of the as-received alloys was characterized. A variety of microstructures was present across the different alloys, ranging from a refined granular ferrite with small amounts of perlite to a bainitic structure containing martensite/austenite islands, retained austenite and small cementite constituents along with a small amount carbides. Similarly, the dislocation structures varied from homogeneously distributed across the ferrite grains to clusters/walls of dislocations. Mechanical tests on macro and micro sized samples were carried out up to 1% and 2% plastic strains. A micro-device for Bauschinger test was designed and manufactured using micro-electro-mechanical-system (MEMS) technology and was incorporated onto a FIB/SEM in order to prepare the micro sized samples and perform the micro Bauschinger tests. The Bauschinger stress parameter showed that the Bauschinger effect becomes more obvious in samples with higher yield strength and also with increasing pre-strain. In addition, the Bauschinger effect remained similar on the samples of different sizes in the current study. The results indicate that the cause of the early yielding during reverse loading of these alloys is dominated by the dislocation-dislocation interaction.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: TN Mining engineering. Metallurgy