Sandia Fracture Challenge Microstructure Characterization
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1 Sandia Fracture Challenge Microstructure Characterization Yuxiong Mao, PhD Mark Horstemeyer, CAVS Chair Professor Center for Advanced Vehicular Systems Mississippi State University
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Sandia Fracture Challenge Microstructure Characterization. Yuxiong Mao, PhD Mark Horstemeyer, CAVS Chair Professor Center for Advanced Vehicular Systems Mississippi State University. 15-5PH Stainless Steel Plate. - PowerPoint PPT Presentation
Transcript of Sandia Fracture Challenge Microstructure Characterization
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Sandia Fracture ChallengeMicrostructure Characterization
Yuxiong Mao, PhDMark Horstemeyer, CAVS Chair
ProfessorCenter for Advanced Vehicular
Systems Mississippi State University
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15-5PH Stainless Steel Plate
• Six samples were made from the received specimen to observe the Longitudinal-Transverse (LT1<2), Longitudinal-Thickness (LS1&LS2), Transverse-Thickness (TS1&TS2) sections.
• Samples were mounted and polished. Then etched with Vilella's reagent for 90 seconds.
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LT1 & LT2 Before Etch
LT1 Overview LT2 Overview
LT sections are homogeneous. Very few inclusions can be found in these sections.Note the lines here are polish scratches.
Inclusions
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LT1 Before Etch
High Resolution View
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LS1 Before EtchNear Surface
Center
High Resolution View
Overview
Inclusions
Banding and inclusions can be observed in LS sections. The inclusions are aligned along the longitudinal direction. The bands run through the entire sample and are clustered in the center region.
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LS2 Before EtchNear Surface
Center
High Resolution View
Overview
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TS1 Before EtchNear Surface
Center
High Resolution View
Overview
Banding and inclusions can also be observed in TS sections. The bands are shorter compared to those in LS sections.
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TS2 Before EtchNear Surface
Center
High Resolution View
Overview
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Quantitative Analyses of the inclusions observed in LS and TS un-etched sections
Area Fraction(%) Number Density(/um^2) Average Area (um^2)Average NND(um)
LS1 0.1014 4.261E-04 2.379 18.578LS2 0.0825 3.164E-04 2.608 20.318TS1 0.1534 7.093E-04 2.162 16.138TS2 0.1649 8.394E-04 1.965 14.474
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LT1 After Etch: Martensite Dominated
Overview High Resolution View
Homogenous Martensitic matrix covers the entire LT sections.
Martensitic matrix
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LT2 After Etch
Overview High Resolution View
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LS1 After Etch: Ferrite Banding is an Issue
Overview
Banding
Near Surface
Center
High Resolution View
Ferrite Stringer
Banding/segregations can be observed in LS sections. The bands run through the entire sample and are clustered in the center region. The bands are aligned along the longitudinal direction. These segregations may have detrimental effects on the mechanical properties(a).
(a) B. Potter, “NDT of Precipitation Hardened Steels Using Fluorescent Magnetic Particle Testing,” NDT Solution, December 2003
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LS2 After Etch
Overview
Near Surface
Center
High Resolution View
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TS1 After Etch
Overview
Near Surface
Center
High Resolution View
Banding/segregations can also be observed in TS sections. The bands are aligned along the transverse direction and are shorter than those in LT sections.
Banding
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TS2 After Etch
Overview
Near Surface
Center
High Resolution View
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Grain Boundary Segmentation
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Grain Size Distributions: Change Hardening Behavior Locally
Sample LT1 LT2 LS1 LS2 TS1 TS2Average
Grain Size (um)
4.54 4.80 4.01 4.30 3.71 3.56
