High-temperature yield strength and its dependence on primary creep and recovery

  1. Get@NRC: High-temperature yield strength and its dependence on primary creep and recovery (Opens in a new window)
DOIResolve DOI: http://doi.org/10.1016/j.msea.2011.03.026
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Journal titleMaterials Science and Engineering A
Pages53665378; # of pages: 13
SubjectAnalytical method; Ceramics; Delayed elasticity; High-temperature; Primary creep; Strain-rate sensitivity; Ti-based Ti-6246; Waspaloy; Yield strength; Alloys; Ceramic materials; Creep; Elasticity; Stress-strain curves; Titanium alloys; Yield stress; Strain rate
AbstractElasto-Delayed-Elastic-Viscous (EDEV), a predictive material model for 'quasi constant-structure' primary creep is used in developing an algorithm for predicting stress-strain diagrams at constant strain rates. The strain rate dependence of the 0.2% offset yield-strength (σy), time to yield, and the amounts of permanent (viscous) and the recoverable (anelastic or delayed elastic) strain components of the 0.2% offset strain can also be evaluated. Six material constants required for calculations can be obtained from short-term (few seconds to a few hours), constant-stress Strain Relaxation and Recovery Tests (SRRTs). The method is illustrated by calculations made for Ni-based fcc alloy, Waspaloy at 732°C (0.62Tm) and Ti-based, alpha (hexagonal)-beta(bcc) alloy Ti-6246 at 600°C (0.45Tm). In the ASTM recommended strain-rate range, 5×10-5s-1 to 1.2×10-4s-1, σy increases by 6% for Waspaloy and 15% for Ti-6246. In this range, the 0.2% offset strain consists of 50% delayed elastic (anelastic) strain for Waspaloy and 70% for Ti-6246. Proportional limit is governed entirely by the delayed elastic effect or the Elasto-Delayed-Elastic (EDE) regime. Intragranular dislocation creep does not play the dominant role up to yield for the materials and temperatures considered, suggesting a shift in paradigm from conventional ideas. The EDEV model, in conjunction with SRRTs (which can be realized using a single specimen), can be used as a tool for characterizing and developing new alloys and ceramics or optimizing processing including grain-boundary engineering. © 2011.
Publication date
AffiliationNational Research Council Canada (NRC-CNRC); Aerospace (AERO-AERO)
Peer reviewedYes
NPARC number21271463
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Record identifierdc33b307-71de-426f-8fc8-bf4c96e0d63d
Record created2014-03-24
Record modified2016-05-09
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