Effect of True Strains in Isothermal <i>abc</i> Pressing on Mechanical Properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> Alloy
The paper analyzes the microstructure and mechanical properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> alloy (at.%) under uniaxial tension at room temperature after isothermal <i>abc</i> pressing to true strains <i>e</i> = 0.29 − 8.44 at <i>T</...
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MDPI AG
2020-09-01
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| Series: | Metals |
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| Online Access: | https://www.mdpi.com/2075-4701/10/10/1313 |
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| author | Oleg Kashin Konstantin Krukovskii Aleksandr Lotkov Victor Grishkov |
| author_facet | Oleg Kashin Konstantin Krukovskii Aleksandr Lotkov Victor Grishkov |
| author_sort | Oleg Kashin |
| collection | DOAJ |
| description | The paper analyzes the microstructure and mechanical properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> alloy (at.%) under uniaxial tension at room temperature after isothermal <i>abc</i> pressing to true strains <i>e</i> = 0.29 − 8.44 at <i>T</i> = 723 K. The analysis shows that as the true strain <i>e</i> is increased, the grain–subgrain structure of the alloy is gradually refined. This leads to an increase in its yield stress σ<sub>y</sub> and strain hardening coefficient θ = <i>d</i>σ/<i>d</i>ε at linear stage III of its tensile stress–strain curve according to the Hall–Petch relation. However, the ultimate tensile strength remains invariant to such refinement. The possible mechanism is proposed to explain why the ultimate tensile strength can remain invariant to the average grains size (<i>d<sub>av</sub></i>). It is assumed that the sharp increase of the ultimate tensile strength σ<sub>UTS</sub> begins when (<i>d<sub>av</sub></i>) is less than the critical average grain size (<i>d<sub>av</sub></i>)<sub>cr</sub>. In our opinion, for the investigated alloy (<i>d<sub>av</sub></i>)<sub>cr</sub> ≈ 0.5 µm. In our study, the attained average grain size is larger the critical one. The main idea of the mechanism is next. In alloys with an average grain size (<i>d<sub>av</sub></i>) less than the critical one, a higher external stress is required for the nucleation and propagation of the main crack. |
| first_indexed | 2024-03-10T15:55:50Z |
| format | Article |
| id | doaj.art-53a0062c081b4925a7310898c886b7a3 |
| institution | Directory Open Access Journal |
| issn | 2075-4701 |
| language | English |
| last_indexed | 2024-03-10T15:55:50Z |
| publishDate | 2020-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Metals |
| spelling | doaj.art-53a0062c081b4925a7310898c886b7a32023-11-20T15:41:28ZengMDPI AGMetals2075-47012020-09-011010131310.3390/met10101313Effect of True Strains in Isothermal <i>abc</i> Pressing on Mechanical Properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> AlloyOleg Kashin0Konstantin Krukovskii1Aleksandr Lotkov2Victor Grishkov3Institute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Sciences, 634055 Tomsk, RussiaInstitute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Sciences, 634055 Tomsk, RussiaInstitute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Sciences, 634055 Tomsk, RussiaInstitute of Strength Physics and Materials Science of the Siberian Branch of the Russian Academy of Sciences, 634055 Tomsk, RussiaThe paper analyzes the microstructure and mechanical properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> alloy (at.%) under uniaxial tension at room temperature after isothermal <i>abc</i> pressing to true strains <i>e</i> = 0.29 − 8.44 at <i>T</i> = 723 K. The analysis shows that as the true strain <i>e</i> is increased, the grain–subgrain structure of the alloy is gradually refined. This leads to an increase in its yield stress σ<sub>y</sub> and strain hardening coefficient θ = <i>d</i>σ/<i>d</i>ε at linear stage III of its tensile stress–strain curve according to the Hall–Petch relation. However, the ultimate tensile strength remains invariant to such refinement. The possible mechanism is proposed to explain why the ultimate tensile strength can remain invariant to the average grains size (<i>d<sub>av</sub></i>). It is assumed that the sharp increase of the ultimate tensile strength σ<sub>UTS</sub> begins when (<i>d<sub>av</sub></i>) is less than the critical average grain size (<i>d<sub>av</sub></i>)<sub>cr</sub>. In our opinion, for the investigated alloy (<i>d<sub>av</sub></i>)<sub>cr</sub> ≈ 0.5 µm. In our study, the attained average grain size is larger the critical one. The main idea of the mechanism is next. In alloys with an average grain size (<i>d<sub>av</sub></i>) less than the critical one, a higher external stress is required for the nucleation and propagation of the main crack.https://www.mdpi.com/2075-4701/10/10/1313TiNiisothermal <i>abc</i> pressingmechanical propertiesaverage grain–subgrain size |
| spellingShingle | Oleg Kashin Konstantin Krukovskii Aleksandr Lotkov Victor Grishkov Effect of True Strains in Isothermal <i>abc</i> Pressing on Mechanical Properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> Alloy Metals TiNi isothermal <i>abc</i> pressing mechanical properties average grain–subgrain size |
| title | Effect of True Strains in Isothermal <i>abc</i> Pressing on Mechanical Properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> Alloy |
| title_full | Effect of True Strains in Isothermal <i>abc</i> Pressing on Mechanical Properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> Alloy |
| title_fullStr | Effect of True Strains in Isothermal <i>abc</i> Pressing on Mechanical Properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> Alloy |
| title_full_unstemmed | Effect of True Strains in Isothermal <i>abc</i> Pressing on Mechanical Properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> Alloy |
| title_short | Effect of True Strains in Isothermal <i>abc</i> Pressing on Mechanical Properties of Ti<sub>49.8</sub>Ni<sub>50.2</sub> Alloy |
| title_sort | effect of true strains in isothermal i abc i pressing on mechanical properties of ti sub 49 8 sub ni sub 50 2 sub alloy |
| topic | TiNi isothermal <i>abc</i> pressing mechanical properties average grain–subgrain size |
| url | https://www.mdpi.com/2075-4701/10/10/1313 |
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