scholarly journals Effects of Applied Strain and Subsequent Heat Treatment at Intermediate Temperature on Mechanical Properties of a Thin Plate Ti–51 at% Ni Shape Memory Alloy

2006 ◽  
Vol 47 (3) ◽  
pp. 772-779
Author(s):  
Hiromasa Semba ◽  
Nagatoshi Okabe ◽  
Toru Yamaji ◽  
Keisuke Okita ◽  
Kiyoshi Yamauchi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thin Plate ◽  
Applied Strain ◽  
Subsequent Heat Treatment ◽  
Intermediate Temperature

Effect of Repeated Heat-Treatment under Constrained Strain on Mechanical Properties of Ti-Ni Shape Memory Alloy

2012 ◽  
Vol 78 ◽  
pp. 69-74
Author(s):  
Hiroki Cho ◽  
Takaei Yamamoto ◽  
Akihiko Suzuki ◽  
Toshio Sakuma ◽  
Kiyoshi Yamauchi
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Martensitic Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Breaking Strength ◽  
Applied Strain ◽  
Shape Memory Alloy Wire ◽  
Breaking Strain ◽  
Alloy Wire

It is well-known that the Ti-Ni shape memory alloy (SMA) is applicable to the medical stent. The repeated heat-treatment under the constrained strain is necessary for the manufacturing process of the laser-cut SMA stent. In this research, the effect of heat-treatment under the constrained strain on mechanical properties of the Ti-Ni shape memory alloy wire was investigated. The applied strain at single heat-treatment (εap) was 4, 5 and 8%, and the heat-treatment is repeated so as to became total applied strain 40%. In the case of εap=4 and 5%, partial transformation occurs in the SMA wire, and so a necking appears in the SMA wire. Due to this necking, multi-step martensitic transformation, and decreasing of breaking strength / breaking strain are caused. The necking does not occur because the whole of the SMA wire is transformed for εap=8%. The mechanical properties are improved by increasing of εap. Nevertheless, the mechanical properties of each sample are inappropriate for the medical stent. However, the mechanical properties of the as-manufactured sample are improved greatly by training. In addition, it is desirable that the applied strain during training is slightly larger than the requested strain for application.

Influence of Cold Working on Deformation Behavior and Shape Memory Effect of Ti-Ni-Nb

2005 ◽  
Vol 475-479 ◽  
pp. 1953-1956 ◽  
Author(s):  
Keisuke Okita ◽  
Nagatoshi Okabe ◽  
Toshio Sakuma ◽  
Hiromasa Semba ◽  
Yuji Mihara
Keyword(s):  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Deformation Behavior ◽  
Shape Recovery ◽  
Cold Working ◽  
Applied Strain ◽  
Recovery Test ◽  
Shape Memory Properties ◽  
The Wire

Thermo-mechanical characteristic of shape memory alloy depends on cold working and heat treatment, because these processes can control the amount of defects including dislocation and precipitation [1]. In this study, the influence of cold working on the deformation behavior and the transformation characteristics was investigated on the Ti-Ni-Nb shape memory alloy (SMA). Both the tensile test and the shape recovery test were performed for the wire specimens of 1mm in the diameter with some different rates of cold working. The shape recovery tests were performed for the wire specimens of different cold working rates until the various levels of maximum applied strain, and the reverse-transformation characteristics on the process of heating after unloading were studied. It is clarified that the higher cold-working rate improves the shape memory properties of the alloy.

Effect of Heat Treatment Temperature on the Mechanical Property in Cast TiNi Shape Memory Alloy

2007 ◽  
Vol 561-565 ◽  
pp. 1493-1496
Author(s):  
Kazuhiro Kitamura ◽  
Yutaka Sawada ◽  
Toshio Kuchida ◽  
Tadashi Inaba ◽  
Masataka Tokuda ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Shape Memory Alloy ◽  
Tensile Test ◽  
Shape Memory ◽  
Treatment Temperature ◽  
Scanning Calorimetry ◽  
Temperature Synthesis ◽  
Treatment Conditions ◽  
High Temperature Synthesis

The heat treatment effect of a cast shape memory alloy (SMA) from self-propagating high temperature synthesis (SHS) ingot was investigated. The composition of SHS ingot was Ti-50.8at%Ni. DSC and Tensile test specimens were cast by lost-wax process from SHS ingot. The heat treatment conditions were 400°C-60min., 500°C-60min. and 600°C-60min. for DSC and 400°C-60min. and 500°C-60min. for tensile test. Transformation temperatures were measured by differential scanning calorimetry (DSC). Mechanical properties were measured by a tensile test at several temperatures. The effects of heat treatment temperatures were same as a general TiNi wire material.

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