Effect of strain path on forming limits and retained austenite transformation in Q&P 1180 steel

Forming limits and retained austenite (RA) transformation in Q&P 1180 steel are quantified as a function of plastic strain levels for three different strain paths. In-plane uniaxial tension testing was performed in a standard test frame, while limiting dome height tooling was employed for out-of...

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Bibliographic Details
Published inMaterials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 734; pp. 192 - 199
Main Authors Cramer, Jeff, Adams, Derrik, Miles, Michael P., Fullwood, David T., Homer, Eric R., Brown, Tyson, Mishra, Raj K., Sachdev, Anil
Format Journal Article
LanguageEnglish
Published Lausanne Elsevier B.V 12.09.2018
Elsevier BV
Subjects
Austenite
Austenitic transformations
Axial stress
Dependence
Electron backscatter diffraction
Forming limit
Forming limits
High strength steel
Necking
Plane strain
Plastic deformation
Q&P steel
Retained austenite
Steel alloys
Strain path
Tension tests
Tooling
Transformations
Yield stress
Retained austenite
Q&P steel
Strain path
Forming limit
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Summary:Forming limits and retained austenite (RA) transformation in Q&P 1180 steel are quantified as a function of plastic strain levels for three different strain paths. In-plane uniaxial tension testing was performed in a standard test frame, while limiting dome height tooling was employed for out-of-plane biaxial and plane strain tension experiments. Sheet specimens were tested incrementally for each strain path, and the RA content at each level of strain was measured using electron backscatter diffraction (EBSD). The biaxial tension strain path resulted in the greatest effective strain prior to necking at 0.355, compared to 0.123 for plane strain and 0.142 for uniaxial tension. EBSD measurements for various levels of plastic strain reveal a clear dependence of RA rate of transformation on strain path for the three linear strain paths that were employed in this work. Thinning strains appear to provide a slightly better correlation to RA transformation than effective strain levels, where biaxial tension achieved the greatest level just prior to necking, followed by plane-strain tension, and then uniaxial tension.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2018.07.062