Experimental analysis of Fe-based shape memory alloy behavior under thermomechanical cyclic loading W. Khalil a,b , L. Saint-Sulpice c,⇑ , S. Arbab Chirani c , C. Bouby a,b , A. Mikolajczak d , T. Ben Zineb a,b,e a Université de Lorraine, LEMTA, UMR 7563, Vandoeuvre-lès-Nancy F-54500, France b CNRS, LEMTA, UMR 7563, Vandoeuvre-lès-Nancy F-54500, France c ENIB, LBMS, Technopôle Brest-Iroise, CS73862, 29238 Brest Cedex 3, France d Université de Lorraine, ESSTIN, Vandoeuvre-lès-Nancy F-54500, France e Khalifa University of Science, Technology, and Research, Abu Dhabi Campus, P.O. Box 127788, Abu Dhabi, United Arab Emirates article info Article history: Received 23 November 2012 Received in revised form 26 March 2013 Available online 18 April 2013 Keywords: Fe-based SMA Thermomechanical behavior Plastic strain Transformation strain Cyclic loading Stress–temperature diagram abstract In this work, the specific thermomechanical behavior of Fe-based Shape Memory Alloys (SMAs) was investigated experimentally. Results show that: (i) such behavior is governed by martensitic transformation and/or plasticity, and depends on both testing temperature and applied mechanical loading level; (ii) phase transformation and plasticity yield stresses are interactive and interdependent; (iii) at low temperatures, the stress-induced martens- ite is activated first, then followed by plasticity activation at a higher loading level, which leads to a coupling of the two mechanisms; (iv) at high temperatures, plasticity activation precedes the possible formation of strain-induced martensite at high stress levels; (v) behavior under thermomechanical cyclic loading shows that the cumulative plasticity sig- nificantly affects the martensitic transformation mechanism. This plasticity seems to pre- vent martensitic variants from forming, and to reduce the shape memory effect. Finally, the stress–temperature diagram was obtained from these experimental results. It summarizes all the possible Fe-based SMA behavior under various thermomechanical loadings. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction Intelligent materials exhibit interesting behavior under multi-physical loadings such as thermomechanical or elec- tromechanical loadings. Among these materials, piezoelec- tric ceramics and shape memory alloys (SMAs) play an important role in various industrial fields. SMAs are con- sidered for applications in many domains such as tighten- ing, transport, civil engineering, etc. Among the main SMA families, Fe-based SMAs have received less interest than for example NiTi, due to their limited corrosion resistance (Charfi et al., 2009; Soderberg et al., 1999) and their low shape memory effect (SME), which is around 3 to 4% (Awaji et al., 2008). However, their good machinability, weldabil- ity and workability (Wen et al., 2007), high mechanical strength and good formability (Bouraoui et al., 2008), and of course their relatively low cost (Sato et al., 2006) are all very attractive attributes, especially for mass-produced applications. Moreover, they present a very large thermal hysteresis, which prevents reverse transformation (mar- tensite to austenite) during cooling. These properties are of great interest in fastening applications like tightening rings for pipeline connections (Awaji et al., 2008) or fish- plate systems used to prevent clearances between crane rails (Maruyama et al., 2008). As it has been well documented, the SME is obtained by heating in order to recover the martensitic transformation strain. In the literature, many experimental studies focus on improving the SME and the corrosion resistance of Fe- based SMAs by applying a thermomechanical training treatment (Charfi et al., 2009; Zhao et al., 1999; Stanford 0167-6636/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.mechmat.2013.04.002 ⇑ Corresponding author. Tel.: +33 2 98 05 66 67. E-mail address: luc.saint-sulpice@enib.fr (L. Saint-Sulpice). Mechanics of Materials 63 (2013) 1–11 Contents lists available at SciVerse ScienceDirect Mechanics of Materials journal homepage: www.elsevier.com/locate/mechmat