Degradation and onset of plastic anisotropy in marine aluminum alloy due to fire exposure by bulk neutron diffraction and in situ loading

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:700

Article

Puplampu, Stephen B.¹  Penumadu, Dayakar¹  Ma, Ran¹  Truster, Timothy J.¹  Woracek, Robin²  Payzant, E. Andrew³  Bunn, Jeffrey R.³ 

[1] Univ Tennessee, Knoxville, TN 37996 USA

[2] European Spallat Source ESS ERIC, SE-22100 Lund, Sweden

[3] Oak Ridge Natl Lab, Oak Ridge, TN 37892 USA

关键词: Neutron scattering;    Strain measurement;    Polycrystal;    Aluminum alloys;    Mechanical properties;    Crystal plasticity;   

DOI  :  10.1016/j.msea.2017.06.050

来源: Elsevier

【 摘 要 】

In this paper, the degradation of mechanical properties of marine structural aluminum alloy AA5083 and onset of lattice plastic anisotropy subsequent to fire exposure is investigated. For virgin and fire-exposed samples, microstructural characterization is carried out for the first time and changes in lattice specific strain responses under step and continuous axial deformation are studied using novel bulk neutron diffraction. Peak fitting of raw data yields d-spacing values of reflections of interest and allows for lattice specific strain calculations. A reduction in yield stress from 260 MPa in the virgin material to 120 MPa in the fire-exposed sample is observed. Virgin material exhibits dynamic strain aging during plastic deformation; this is captured in neutron diffraction measurements. Larger peak broadening for virgin material indicates possible presence of Type II and III residual stresses due to intergranular stress or dislocation stress fields. Stress vs. lattice strain plots show large deviations from linearity post-yield for fire-exposed samples. This is due to strain redistribution among grains as well as grain reorientation. After fire exposure dynamic strain aging does not occur, but individual lattice planes reveal plastic anisotropy in their response to plastic deformation. Results from neutron diffraction, combined with electron backscatter diffraction characterization, provide insight into the yielding mechanisms of AA5083 and effects of fire exposure.

【 授权许可】

Free