Improvement of shape memory effect by ausforming in Fe–28Mn–6Si–5Cr alloy

Effect of the Manufacturing Process on the Texture and the Fraction of Stress-induced Martensite in an Fe-Mn-Si-Cr-Ni Shape Memory Alloy

“…Tel. : +54-341-4853200; fax: +54-341-4218834 E-mail address: druker@ifir-conicet.gov.ar investigations have followed, for example Sato et al (1984Sato et al ( , 1986, Otsuka et al (1990), Watanabe et al (1993), Gu et al(1994), Kajiwara et al (1999Kajiwara et al ( , 2001, Wang et al(2001), Baruj et al (2004), Stanford and Dunne (2006), Wen et al (2010Wen et al ( , 2011, Min et al (2012). The shape memory effect (SME) is due to a reversible (austenite, FCC) (martensite, HCP) martensitic transformation that is carried out by the selective movement of a/6 [112] Shockley partial dislocations belonging to a single variant, on the {111} planes of the austenite.…”

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

“…[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.…”

“…[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.…”

“…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).…”

Large recovery strain in Fe-Mn-Si-based shape memory steels obtained by engineering annealing twin boundaries

“…In addition, some studies showed that irrespective of the chemical composition, the RS of the Fe-Mn-Si-based SMSs can be improved up to B5% from 2-3% by training, that is, the repetition of a cycle consisting of 3-5% tensile deformation at room temperature and subsequent annealing between 873 and 923 K (refs 6,22-26). In addition to this special thermomechanical treatment, both the thermo-mechanical treatment of a tensile deformation at 973 K, that is, ausforming 27,28 and that of 10% cold rolling and subsequent annealing at B973 K can remarkably enhance their RS 9 , which is also independent of the specific chemical composition. Accordingly, the chemical composition is not the critical factor in controlling the RS in the Fe-Mn-Si-based SMSs.…”