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Title: Direct measurement of critical resolved shear stress of prismatic and basal slip in polycrystalline Ti using high energy X-ray diffraction microscopy

Knowledge of the critical resolved shear stress (CRSS) values of different slip modes is important for accurately modeling plastic deformation of hexagonal materials. Here, we demonstrate that CRSS can be directly measured with an in-situ high energy X-ray diffraction microscopy (HEDM) experiment. A commercially pure Ti tensile specimen was deformed up to 2.6% strain. In-situ far-field HEDM experiments were carried out to track the evolution of crystallographic orientations, centers of masses, and stress states of 1153 grains in a material volume of 1.1mm×1mm×1mm. Predominant prismatic slip was identified in 18 grains, where the orientation change occurred primarily by rotation around the c-axis during specimen deformation. By analyzing the resolved shear stress on individual slip systems, the estimated CRSS for prismatic slip is 96±18 MPa. Predominant basal slip was identified in 22 other grains, where the 2 orientation change occurred primarily by tilting the c-axis about an axis in the basal plane. The estimated CRSS for basal slip is 127±33 MPa. The ratio of CRSS basal/CRSS prismatic is in the range of 1.7-2.1. From indirect assessment, the CRSS for pyramidal < c+a > slip is likely greater than 240MPa. Lastly, grain size and free surface effects on the CRSS value inmore » different grains are also examined.« less
Authors:
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Publication Date:
Grant/Contract Number:
AC02-06CH11357; DESC0002001; AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 132; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; Critical resolved shear stress; Crystal plasticity; High-energy X-ray diffraction; In situ tension test; Titanium
OSTI Identifier:
1373591
Alternate Identifier(s):
OSTI ID: 1397863