### Abstract

A novel method for calculating the critical resolved shear stress (CRSS) ratios of different deformation system types in polycrystalline non-cubic metals has been developed. The mean CRSS ratios between different deformation systems were calculated for both commercially pure (CP) Ti and Ti-5Al-2.5Sn (wt.%) tensile deformed at ambient temperature and 455 C using an in situ scanning electron microscope-based testing technique combined with electron backscattered diffraction. It was found that the relative activity of the different deformation systems changes as a function of alloying composition and deformation temperature. Prismatic slip was the most active deformation mode for CP Ti. CP Ti exhibited a lower resistance to prismatic slip at both ambient and elevated temperatures compared with Ti-5Al-2.5Sn. For Ti-5Al-2.5Sn, prismatic slip was the most active deformation system at ambient temperature although the basal slip activity significantly increased compared to CP Ti, mostly likely due to an increased c/a ratio resulting in a closer packed basal plane. At 455 C, basal slip exhibited a lower CRSS than prismatic slip for Ti-5Al-2.5Sn. The relative activity of other deformation systems was also affected by alloying and temperature. The statistical resampling technique of bootstrapping was used to generate multiple equivalent data sets from which mean CRSS ratios between different deformation systems, and associated confidence intervals, could be deduced. It was found that the mean CRSS ratios at low and high strains varied slightly for the same testing conditions. Moreover, lesser activated slip systems resulted in relatively larger confidence intervals for the CRSS means. This variability may be attributed to a number of potential factors, including measurement errors, rotations of grains during deformation, local stress state variations, and work hardening. The analysis further suggests that awareness of the intrinsic statistical variability in CRSS ratios should be considered when formulating crystal plasticity constitutive models.

Original language | English (US) |
---|---|

Pages (from-to) | 7555-7567 |

Number of pages | 13 |

Journal | Acta Materialia |

Volume | 61 |

Issue number | 20 |

DOIs | |

State | Published - Dec 2013 |

### Profile

### Keywords

- Critical resolved shear stress
- Deformation behavior
- Schmid factor
- Tension
- Titanium

### ASJC Scopus subject areas

- Ceramics and Composites
- Metals and Alloys
- Polymers and Plastics
- Electronic, Optical and Magnetic Materials

### Cite this

**Methodology for estimating the critical resolved shear stress ratios of α-phase Ti using EBSD-based trace analysis.** / Li, H.; Mason, D. E.; Bieler, T. R.; Boehlert, C. J.; Crimp, M. A.

Research output: Contribution to journal › Article

*Acta Materialia*, vol 61, no. 20, pp. 7555-7567. DOI: 10.1016/j.actamat.2013.08.042

}

TY - JOUR

T1 - Methodology for estimating the critical resolved shear stress ratios of α-phase Ti using EBSD-based trace analysis

AU - Li,H.

AU - Mason,D. E.

AU - Bieler,T. R.

AU - Boehlert,C. J.

AU - Crimp,M. A.

PY - 2013/12

Y1 - 2013/12

N2 - A novel method for calculating the critical resolved shear stress (CRSS) ratios of different deformation system types in polycrystalline non-cubic metals has been developed. The mean CRSS ratios between different deformation systems were calculated for both commercially pure (CP) Ti and Ti-5Al-2.5Sn (wt.%) tensile deformed at ambient temperature and 455 C using an in situ scanning electron microscope-based testing technique combined with electron backscattered diffraction. It was found that the relative activity of the different deformation systems changes as a function of alloying composition and deformation temperature. Prismatic slip was the most active deformation mode for CP Ti. CP Ti exhibited a lower resistance to prismatic slip at both ambient and elevated temperatures compared with Ti-5Al-2.5Sn. For Ti-5Al-2.5Sn, prismatic slip was the most active deformation system at ambient temperature although the basal slip activity significantly increased compared to CP Ti, mostly likely due to an increased c/a ratio resulting in a closer packed basal plane. At 455 C, basal slip exhibited a lower CRSS than prismatic slip for Ti-5Al-2.5Sn. The relative activity of other deformation systems was also affected by alloying and temperature. The statistical resampling technique of bootstrapping was used to generate multiple equivalent data sets from which mean CRSS ratios between different deformation systems, and associated confidence intervals, could be deduced. It was found that the mean CRSS ratios at low and high strains varied slightly for the same testing conditions. Moreover, lesser activated slip systems resulted in relatively larger confidence intervals for the CRSS means. This variability may be attributed to a number of potential factors, including measurement errors, rotations of grains during deformation, local stress state variations, and work hardening. The analysis further suggests that awareness of the intrinsic statistical variability in CRSS ratios should be considered when formulating crystal plasticity constitutive models.

AB - A novel method for calculating the critical resolved shear stress (CRSS) ratios of different deformation system types in polycrystalline non-cubic metals has been developed. The mean CRSS ratios between different deformation systems were calculated for both commercially pure (CP) Ti and Ti-5Al-2.5Sn (wt.%) tensile deformed at ambient temperature and 455 C using an in situ scanning electron microscope-based testing technique combined with electron backscattered diffraction. It was found that the relative activity of the different deformation systems changes as a function of alloying composition and deformation temperature. Prismatic slip was the most active deformation mode for CP Ti. CP Ti exhibited a lower resistance to prismatic slip at both ambient and elevated temperatures compared with Ti-5Al-2.5Sn. For Ti-5Al-2.5Sn, prismatic slip was the most active deformation system at ambient temperature although the basal slip activity significantly increased compared to CP Ti, mostly likely due to an increased c/a ratio resulting in a closer packed basal plane. At 455 C, basal slip exhibited a lower CRSS than prismatic slip for Ti-5Al-2.5Sn. The relative activity of other deformation systems was also affected by alloying and temperature. The statistical resampling technique of bootstrapping was used to generate multiple equivalent data sets from which mean CRSS ratios between different deformation systems, and associated confidence intervals, could be deduced. It was found that the mean CRSS ratios at low and high strains varied slightly for the same testing conditions. Moreover, lesser activated slip systems resulted in relatively larger confidence intervals for the CRSS means. This variability may be attributed to a number of potential factors, including measurement errors, rotations of grains during deformation, local stress state variations, and work hardening. The analysis further suggests that awareness of the intrinsic statistical variability in CRSS ratios should be considered when formulating crystal plasticity constitutive models.

KW - Critical resolved shear stress

KW - Deformation behavior

KW - Schmid factor

KW - Tension

KW - Titanium

UR - http://www.scopus.com/inward/record.url?scp=84886313371&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84886313371&partnerID=8YFLogxK

U2 - 10.1016/j.actamat.2013.08.042

DO - 10.1016/j.actamat.2013.08.042

M3 - Article

VL - 61

SP - 7555

EP - 7567

JO - Acta Materialia

T2 - Acta Materialia

JF - Acta Materialia

SN - 1359-6454

IS - 20

ER -