Download file (2.62MB)
Download as zip (2.02MB)

コレクション

引用

説明:

Extremely low cycle fatigue tests, up to a total axial strain amplitude of 10%, were conducted on Fe-15Mn-10Cr-8Ni-4Si bidirectional transformation-induced plasticity (B-TRIP) steel. The fatigue life was approximately five times longer than that of SUS316 when the total strain amplitude was 4% or higher. The improved fatigue life of Fe-15Mn-10Cr-8Ni-4Si was attributed to reversible bidirectional γ ↔ ε transformation during fatigue deformation, which might mitigate fatigue damage. In contrast, the fatigue life tended to decrease with increasing strain rate when the strain rate was varied from 0.1 to 2.5%/s with a total strain amplitude of 10%. Fractography revealed that the fracture surface varied significantly with strain rate. At low strain rates, crystallographic fracture surfaces characterized by facets and secondary cracks were observed, whereas these features were not observed at high strain rates. Electron backscatter diffraction measurements of the postmortem microstructure showed that frequent ε-martensite formation occurred at low strain rates, whereas martensitic transformation was suppressed at high strain rates. The change in the specimen surface temperature was evaluated in terms of the Gibbs free energy difference between γ-austenite and ε-martensite (i.e., ΔGγ→ε), and the effect of strain rate on the extremely low cycle fatigue was discussed from the viewpoint of the deformation mechanism. At a low strain rate, the condition for B-TRIP to work effectively, that is, ΔGγ→ε is negative but close to zero, was maintained over the entire life span. At a high strain rate, the deformation mechanism changed to one in which γ-austenite was dominant because of the increase in ΔGγ→ε caused by self-heating; the fatigue damage mitigation mechanism provided by B-TRIP was less likely to occur at high strain rates, which reduced the fatigue life.

権利情報:

• In Copyright
  

キーワード: fatigue, fracture surface, extremely low cycle fatigue, microstructure, martensitic transformation, seismic damper

刊行年月日: 2024-07-01

出版者: Japan Institute of Metals

掲載誌:

• MATERIALS TRANSACTIONS (ISSN: 13459678) vol. 65 issue. 7 MT-Z2024002

研究助成金:

• 日本学術振興会 19K14853 (疲労損傷のマルチスケール的観察が結びつける転位-塑性変形-き裂関係)
• 日本学術振興会 23K13227 (可逆双方向TRIPを活用した疲労き裂制御による耐疲労合金創製)
• 日本学術振興会 20K04170 (大地震を模擬した高速ひずみ速度の極低サイクル繰り返し変形による疲労損傷の解明)

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.2320/matertrans.mt-z2024002

関連資料:

その他の識別子:

連絡先:

更新時刻: 2024-08-03 08:30:22 +0900

MDRでの公開時刻: 2024-08-03 08:30:22 +0900