Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session S5: Materials Science I |
Hide Abstracts |
Chair: Neil Bourne, Atomic Weapons Establishment Room: Renaissance Ballroom D |
Thursday, June 30, 2011 9:15AM - 9:30AM |
S5.00001: The Role of Interfaces on Dynamic Damage in Two Phase Metals Ellen Cerreta, Saryu Fensin, George Gray III, Adam Farrow, Carl Trujillo, Mike Lopez For ductile metals, the process of dynamic fracture during shock loading is thought to occur through nucleation of voids, void growth, and then coalescence that leads to material failure. Particularly for high purity metals, it has been observed by numerous investigators that voids appear to heterogeneously nucleate at grain boundaries. However, for materials of engineering significance, those with inclusions, second phase particles, or chemical banding it is less clear what the role of grain boundaries versus other types of interfaces in the metal will be on nucleation of damage. To approach this problem in a step-wise fashion four materials have been investigated: high purity copper, copper with 1{\%} lead, 260 brass, and a leaded 360 brass. These materials have all been shock loaded at 2GPa and soft recovered. In-situ VISAR and post mortem metallography reveals significantly less damage in the metals with no lead. The role of lead at grain boundary triple points and its behavior during shock loading will be discussed. [Preview Abstract] |
Thursday, June 30, 2011 9:30AM - 9:45AM |
S5.00002: Effects of grain size and boundary structure on the dynamic tensile response of copper Juan Escobedo, Darcie Dennis-Koller, Ellen Cerreta, Brian Patterson, Curt Bronkhorst Plate impact experiments were conducted to examine the influence of defect density, i.e. grain boundary distribution, on the dynamic tensile response of Cu. Grain boundary distribution and grain size was altered through heat treatment. The peak compressive stress was maintained at $\sim $1.5 GPa for all experiments, low enough to cause an early stage of incipient spall damage that can be correlated to the surrounding. The post-impact metallographic analyses showed that for the materials with grain sizes larger than 30 $\mu $m the void volume fraction and the average void size increased with increasing grain size. In the 30 and 200 $\mu $m samples, void growth and coalescence was observed to dominate the damage behavior, whereas in 60 and 100 $\mu $m sized grains samples, most of the damage was restricted to individual, isolated voids. Electron backscatter diffraction (EBSD) observations showed that voids preferentially nucleate and grow at grain boundaries with high angle misorientation. However, special boundaries corresponding to $\Sigma $l (low angle, $<$5$^{\circ})$ and $\Sigma $3 ($\sim $ 60$^{\circ} \quad <$111$>$ misorientation) type were more resistant to void formation. Finally, micro x-ray tomography results showed 3D views of the damage fields consistent with the 2D surface observations. An overall agreement was found among all the measurements. Work supported by LDRD-DR 20100026. [Preview Abstract] |
Thursday, June 30, 2011 9:45AM - 10:00AM |
S5.00003: Evaluation of the dynamic properties of 30HGSA hardened steel experimentally subjected to shock in the region of solid-to-solid phase transformation Alexander Petrovtsev, Sergey Brichikov, Denis Varfolomeyev, Natalya Zhilyaeva, Evgenii Kozlov, Vladimir Nogin, Vladislav Tarzhanov, Denis Shalkovsky The paper describes models of shear and spall strength for 30HGSA HRc35...40 hardened steel with allowance for the alpha-epsilon transition. The models are based on results of experiments where two- and three-stress-wave configurations were registered in the material. The paper provides some results from the simulation of shock experiments where wave profiles in 30HGSA steel were registered with laser interferometry and compares them with the measured wave profiles and characteristics of fracture visually seen on the cross-sectional photos of recovered samples. The complicated multi-wave pattern of wave profile formation in experiments with shells is discussed. The profile results from the local initiation of the HE-layer, and the evolution of the profiles as the wave converges with the increasing shell thickness. [Preview Abstract] |
Thursday, June 30, 2011 10:00AM - 10:15AM |
S5.00004: Effects of heat-treatment and explosive brisance on fragmentation of high strength steel James Stolken, Mukul Kumar, Vladimir Gold, Ernest Baker Tubes of AISI-4340 steel were heat-treated to three distinct microstructures resulting in nominal hardness values of 25 Rc, 38 Rc and 48 Rc. The specimens were then explosively fragmented using TNT and PETN. The experiments were conducted in a contained firing facility with high fragment collection efficiency. Statistical analyses of recovered fragments were performed. Fragment rank-order statistics and generalized goodness-of-fit tests were used to characterize the fragment mass distributions. These analyses indicated significant interaction effects between the heat-treatment (and the resulting microstructure) and the explosive brisance. The role of the microstructure in relation to the yield-strength and toughness will also be discussed. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. [Preview Abstract] |
Thursday, June 30, 2011 10:15AM - 10:45AM |
S5.00005: Controlled Shock Loading Conditions for Microstructural Correlation of Dynamic Damage Behavior Invited Speaker: Materials performance is recognized as being central to many emergent technologies. Future technologies will place increasing demands on materials performance with respect to extremes in stress, strain, temperature, and pressure. In this study, the dynamic ductile damage evolution of OFHC Cu is explored as a test bed to understand the role of spatial effects due to loading profile and defect density. Well characterized OFHC Cu samples of 30 $\mu $m, 60 $\mu $m, 100 $\mu $m, and 200 $\mu $m grain sizes were subjected to plate impact uniaxial strain loading at 1.5 GPa. This spall geometry produced early stage (insipient) damage in the Cu samples that could be correlated to microstructural features in metallographic analysis. The recovered damaged microstructure was examined using traditional 2D metallographic techniques (optical and electron microscopy) as well as 3D x-ray microtomography. Calculated spall strength from the free surface velocimetry (VISAR) showed no change with respect to changes in grain size, however, the magnitude of the peak after the first pull-back as well as rate of re-acceleration are dependent on grain size and can be correlated to damage observed in the recovered samples. These results reveal a critical length scale for the transition from a nucleation dominated regime to a growth dominated regime for the damage evolution process. The results show that for samples with small (30 $\mu $m) and large (200 $\mu $m) grain sizes the growth of voids is dominated by coalescence, whereas for medium (60 $\mu $m and 100 $\mu $m) grain sizes the growth is restricted to a much slower process of individual void growth. Electron backscatter diffraction reveals that voids preferentially nucleate at grain boundaries with high misorientation angles while special boundaries (low angle $\sum $1 and high angle $\sum $3) proved to be resistant to void nucleation. Based on these findings, mechanisms for the void nucleation/growth and coalescence are proposed. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700