Characteristic Structural Changes in Stress-Induced Martensitic Transformation and Reverse Transformation of a Polycrystalline Fe-Mn-Si Alloy

Suzuki, Shigeru; Senoo, Shotaro; Maruyama, Toru; Shinoda, Kōzō

doi:10.2320/matertrans.mra2008211

Cited by 10 publications

(4 citation statements)

References 21 publications

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“…This is because the accumulation of irreversible slip increases with an increase in the training cycles [40]. Meanwhile, what cannot be ignored is that irreversible martensite still exists and increases after the heating process at each training cycle [41]. Figure 12 shows the temperature rise during the tension with four training cycles at 1×10 −1 and 493 s −1…”

Section: Experimental Results Of Training Processmentioning

confidence: 99%

Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading

Sun

Cao

Iwamoto

et al. 2021

Sci. China Technol. Sci.

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In the past studies, it has been discovered that the shape memory effect (SME) in the Fe-Mn-Si shape memory alloy (Fe-SMA) can gradually be enhanced by a pre-process called as shape memory training process under cyclic thermo-mechanical loading. On the other hand, it has been shown that the SME of Fe-SMA can also be affected by changing the strain rate. Therefore, it is possible to improve the SME by combining the strain rate sensitivity and shape memory training process. However, the improvement of SME caused by the training process under impact condition is still unclear. For the training process under impact condition, it is difficult to interrupt the test at the desired strain level due to many reflections of stress waves, which reload the specimen from the free ends. In this paper, to obtain reliable experimental results of SME after the training process under impact condition, the stress waves after first loading are eliminated by the double momentum-trap structure introduced into the impact tensile testing apparatus based on the split Hopkinson pressure bar method. In order to achieve an optimum design of the structure used in experiments, the finite element simulation of the structure is performed. Then, tensile tests in the training process of Fe-28Mn-6Si-5Cr alloy at different strain rates including the impact level are conducted and temperature change of the specimen is measured during training and heating process. As a result, the improvement of SME in the alloy after the training process under quasi-static and impact loading is compared with that under quasi-static loading through verification processes. Fe-Mn-Si shape memory alloy, training, cyclic thermo-mechanical process, split Hopkinson pressure bar, momentumtrap, impact deformation Citation: Sun Q, Cao B, Iwamoto T, et al. Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading.

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Section: Experimental Results Of Training Processmentioning

confidence: 99%

Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading

Sun

Cao

Iwamoto

et al. 2021

Sci. China Technol. Sci.

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Section: Discussionmentioning

confidence: 99%

“…For Fe‐Mn‐Si based SMAs, dislocations and α′ martensite will be introduced after deformation besides SIEM 29, 30. After the deformed specimen is annealed, the dislocations and α′ martensite will remain or disappear, depending on the annealing temperature 24, 30. If the annealing temperature is low, the dislocations and α′ martensite will remain, and some stacking faults will be introduced, resulting from the decomposition of thick SIEM during the reverse transformation 17, 18.…”

Section: Discussionmentioning

confidence: 99%

A Role of α′ Martensite Introduced by Thermo‐Mechanical Treatment in Improving Shape Memory Effect of an Fe‐Mn‐Si‐Cr‐Ni Alloy

et al. 2011

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The evolution of α′ martensite with different thermo‐mechanical treatment and its effect on the shape memory effect were studied in an Fe‐14Mn‐5Si‐8Cr‐4Ni alloy. The α′ martensite was introduced by only 5% pre‐deformation, and its amount increased with increasing pre‐deformation up to 20%. The α′ martensite started to transform into austenite when the annealing temperature was 773 K. As the annealing temperature increased to 1 073 K, the α′ martensite almost transformed fully into austenite. The α′ martensite introduced by the thermo‐mechanical treatment could prevent collisions between different ε martensite bands during deformation. The intrusion of α′ martensite was another key reason that the stress‐induced ε martensite bands in Fe‐Mn‐Si based shape memory alloys formed in a domain‐specific manner in addition to that of uniformly distributed stacking faults after thermo‐mechanical treatment.

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“…After being subsequently annealed at 873 K (600°C), the alloy's shape recovery ratio further increased to 90 pct due to the reduction in the dislocations, which inhibit the stress-induced e-martensitic transformation. [13,[37][38][39] On the contrary, after being subsequently annealed at 1373 K (1100°C), the alloy's shape recovery ratio decreased to 76 pct because of the reduction in the amount of stacking faults, which are beneficial to stress-induced e-martensitic transformation. [5] For solution-treated alloy after heating at 1523 K (1250°C) and air cooling, a high density of twin boundaries, which has a negative effect on the shape memory effect, still existed ( Figure 3).…”

mentioning

confidence: 93%

A Novel Training-Free Processed Fe-Mn-Si-Cr-Ni Shape Memory Alloy Undergoing δ → γ Phase Transformation

Peng

Wang

Du³

et al. 2016

Metall Mater Trans A

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We not only suppress the formation of twin boundaries but also introduce a high density of stacking faults by taking advantage of d fi c phase transformation in a processed Fe-19.38Mn-5.29Si-8.98Cr-4.83Ni shape memory alloy. As a result, its shape memory effect is remarkably improved after heating at 1533 K (1260°C) (single-phase region of d ferrite) and air cooling due to d fi c phase transformation.Low-cost Fe-Mn-Si-based shape memory alloys (SMAs), possessing one-way shape memory effect, have attracted much attention for several decades as a possible alternative to the expensive Ti-Ni-based SMAs. [1][2][3][4][5][6] A large recovery strain of 9 pct has been reported in a single-crystalline Fe-30Mn-1Si alloy. [1] However, only 2 to 3 pct recovery strain is attained in ordinary polycrystalline-processed Fe-Mn-Si-based alloys without special treatment. [4][5][6] There are three kinds of special treatment-training, [7][8][9] thermomechanical, [5,10,11] and ausforming [12,13] -that improve the recovery strain of polycrystalline-processed Fe-Mn-Si SMAs to 4 to 5 pct. The preceding treatments not only increase the production cost, but also make it difficult to fabricate the components with complicated shape. Recently, we manufactured a novel training-free cast Fe-20.2Mn-5.6Si-8.9Cr-5.0Ni alloy by simple synthesis processing, consisting only of casting plus annealing, and made a breakthrough to attain a tensile recovery strain of 7.6 pct in this cast alloy. [14] Nevertheless, there are still shortcomings for cast alloys as compared with processed alloys, i.e., lower recovery stress and worse mechanical properties. Thus, we raise an issue regarding how to obtain training-free processed Fe-Mn-Si-based SMAs.Recently, we investigated the interaction between twin boundaries and stress-induced e martensite in Fe-MnSi-based SMAs and found that this interaction not only suppresses the stress-induced e martensitic transformation, but also severely distorts the twin interfaces. [14] As a result, a high density of twin boundaries results in a poor shape memory effect in processed Fe-Mn-Si-based SMAs, and a good shape memory effect could be obtained by inhibiting the formation of twin boundaries. Furthermore, Kajiwara indicated that a high density of stacking faults is beneficial to obtaining a good shape memory effect for processed Fe-Mn-Si-based SMAs. [5] Indeed, the previously mentioned special treatments that effectively improve the shape memory effect introduce the high density of stacking faults besides reducing the twin boundaries for processed Fe-Mn-Si-based SMAs. [5,8,[13][14][15] Here, we also achieve the purpose of both reducing the twin boundaries and introducing the high density of stacking faults using d fi c phase transformation in a Fe-19.38Mn-5.29Si-8.98Cr-4.83Ni alloy. Therefore, in the present article, a novel training-free processed Fe-Mn-Si-Cr-Ni alloy is developed based on d fi c phase transformation.The ingot of Fe-19.38Mn-5.29Si-8.98Cr-4.83Ni SMA was prepared by induction melting in an argon atmosphere. Thi...

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Characteristic Structural Changes in Stress-Induced Martensitic Transformation and Reverse Transformation of a Polycrystalline Fe-Mn-Si Alloy

Cited by 10 publications

References 21 publications

Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading

Effect of impact deformation on shape recovery behavior in Fe-Mn-Si shape memory alloy under shape memory training process with cyclic thermo-mechanical loading

A Role of α′ Martensite Introduced by Thermo‐Mechanical Treatment in Improving Shape Memory Effect of an Fe‐Mn‐Si‐Cr‐Ni Alloy

A Novel Training-Free Processed Fe-Mn-Si-Cr-Ni Shape Memory Alloy Undergoing δ → γ Phase Transformation

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