TY - JOUR

T1 - Influence of thermomechanical treatment on the shape memory effect and pseudoelasticity behavior of conventional and additive manufactured Fe–Mn–Si–Cr–Ni-(V,C) shape memory alloys

AU - Mohri, Maryam

AU - Ferretto, Irene

AU - Khodaverdi, Hesamodin

AU - Leinenbach, Christian

AU - Ghafoori, Elyas

N1 - Funding Information: This research was partly supported by the EMPA POSTDOCS-II program that received funding from the European Union Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement number 754364 . The authors thank voestalpine BÖHLER Edelstahl GmbH & Co KG for providing the powder for the LPBF experiments. The authors (M.M and E.G) also gratefully acknowledges Prof. Mahmoud Nili-Ahmadabadi at Advanced Phase Transformation Laboratory, University of Tehran for providing TEM measurment.

PY - 2023/5

Y1 - 2023/5

N2 - This study evaluated the influence of heat treatment and thermomechanical training on the microstructural evolution and mechanical characteristics of conventional and additive-manufactured FeMnSi-based shape memory alloys. The conventional samples were produced by casting and rolling. The additive-manufactured samples were manufactured using the laser powder bed fusion (L-PBF) technique. Both specimens were subjected to the same heat treatment and thermomechanical training. The heat treatment involved solution annealing at 1050 °C for 2 h and aging at 750 °C for 6 h, and the thermomechanical training concluded with a 4% elongation at ambient temperature followed by annealing at 250 °C for 15 min. This training cycle was repeated four times for each sample after heat treatment. The heat treatment improved the pseudoelasticity and shape memory effect of the samples. Although training further enhanced the pseudoelasticity, it also reduced the shape memory effect. Thermomechanical training led to the formation of a large number of stacking faults, which facilitated the inverse phase transformation of martensite (ε) to austenite (γ) during unloading, resulting in improved pseudoelasticity. The heat-treated additive-manufactured samples showed the highest total recovery strain owing to the pseudoelasticity and shape memory effect. This characteristic could be due to the smaller grain size and higher volume fraction of precipitates. The precipitates and grain refinement improved the conditions for partial dislocation motion by increasing the back stresses on the martensite tip.

AB - This study evaluated the influence of heat treatment and thermomechanical training on the microstructural evolution and mechanical characteristics of conventional and additive-manufactured FeMnSi-based shape memory alloys. The conventional samples were produced by casting and rolling. The additive-manufactured samples were manufactured using the laser powder bed fusion (L-PBF) technique. Both specimens were subjected to the same heat treatment and thermomechanical training. The heat treatment involved solution annealing at 1050 °C for 2 h and aging at 750 °C for 6 h, and the thermomechanical training concluded with a 4% elongation at ambient temperature followed by annealing at 250 °C for 15 min. This training cycle was repeated four times for each sample after heat treatment. The heat treatment improved the pseudoelasticity and shape memory effect of the samples. Although training further enhanced the pseudoelasticity, it also reduced the shape memory effect. Thermomechanical training led to the formation of a large number of stacking faults, which facilitated the inverse phase transformation of martensite (ε) to austenite (γ) during unloading, resulting in improved pseudoelasticity. The heat-treated additive-manufactured samples showed the highest total recovery strain owing to the pseudoelasticity and shape memory effect. This characteristic could be due to the smaller grain size and higher volume fraction of precipitates. The precipitates and grain refinement improved the conditions for partial dislocation motion by increasing the back stresses on the martensite tip.

KW - 4D printing

KW - Fe-based shape memory alloy

KW - Metal AM

KW - Pseudoelasticity

KW - Shape memory effect

KW - Training

UR - http://www.scopus.com/inward/record.url?scp=85156166297&partnerID=8YFLogxK

U2 - 10.1016/j.jmrt.2023.04.195

DO - 10.1016/j.jmrt.2023.04.195

M3 - Article

AN - SCOPUS:85156166297

VL - 24

SP - 5922

EP - 5933

JO - Journal of Materials Research and Technology

JF - Journal of Materials Research and Technology

SN - 2238-7854

ER -