Advanced Shape Memory Alloys: From Additive Manufacturing to Smart Steel Structures

Webinar 1

SPEAKER I

Xiebin Wang (University of Shandong, China)

Additive Manufacturing of NiTiNb Shape Memory Alloys

 

Abstract: Adding ternary alloying elements is an efficient strategy to modulate the phase transformation behavior and functional properties, thus expanding the practical applications of NiTi-based shape memory alloys (SMAs). However, it is quite challenging to fabricate ternary SMAs via conventional metallurgical techniques, mainly due to the large difference in melting points, as well as the high chemical reactivity of the elements. Laser powder bed fusion (L-PBF), as an additive manufacturing technique, is attracting increasing interest due to its ability to fabricate geometrically complex structures. Also, L-PBF is a potential approach for in-situ alloying, since the melt-pool flow behavior is very dynamic due to the Marangoni convection and recoil pressure, which lead to intensive mixing of the melts. Together with the ability to fabricate complex structures and the feasibility to tune the phase transformation behavior, L-PBF provides great potential for producing NiTi-based shape memory alloy structures with novel functionalities.

 

Related publications:

  • R. Xi, H. Jiang, S. Kustov, Z. Zhang, G. Zhao, K. Vanmeensel, J. Van Humbeeck, X. Wang. Influence of Nb addition and process parameters on the microstructure and phase transformation behavior of NiTiNb ternary shape memory alloys fabricated by laser powder bed fusion. Scripta Materialia, 2023, 222: 114996. https://doi.org/10.1016/j.scriptamat.2022.114996
  • X. Wang, J. Yu, J. Liu, L. Chen, Q. Yang, H. Wei, J. Sun, Z. Wang, Z. Zhang, G. Zhao, J. Van Humbeeck. Effect of process parameters on the phase transformation behavior and tensile properties of NiTi shape memory alloys fabricated by selective laser melting. Additive Manufacturing, 2020, 36: 101545. https://doi.org/10.1016/j.addma.2020.101545

SPEAKER II

Elyas Ghafoori (Leibniz University of Hannover, Germany)

Memory-Steel for Smart Steel Structures

 

Abstract: This presentation explores the development and application of iron-based shape memory alloy (Fe-SMA), the so-called memory-steel, for steel structures. First, the studies on the material properties of Fe-SMA in terms of shape memory effect and superelasticity are discussed. Next, the use of Fe-SMA in a prestressed strengthening of steel structures is explained, including the applications in strengthening steel girders, connections, and fatigue crack repairs. Various strengthening solutions such as using mechanically anchored or adhesively-bonded Fe-SMA, as well as the studies on the behavior of the Fe-SMA-to-steel bonded joints, are discussed. The use and application of Fe-SMA for strengthening a 113-years steel bridge has been explained. In addition, studies on the innovative application of the Fe-SMA as pipe couplers are presented. In the end, innovative ongoing research on the additive manufacturing of architected Fe-SMA (4D-printing) is discussed.

 

Related publications:

  • Wang, S., Mohri, M., Li, L., Izadi, M., Jafarabadi, A., Pichler, N., & Ghafoori, E. (2023). Memory‐Steel for Smart Steel Structures: A Review on Recent Developments and Applications. ce/papers, 6(3-4), 949-958.