Effect of Cold-Working Ratio on Superelastic Cyclic Behavior and Fatigue Life in Ti-41.7Ni-8.5Cu (at%) Shape-Memory Alloy Wire

2002 ◽  
Vol 394-395 ◽  
pp. 257-260 ◽  
Author(s):  
Maho Hosogi ◽  
Nagatoshi Okabe ◽  
Toshio Sakuma ◽  
Keisuke Okita
Keyword(s):  
Fatigue Life ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Cold Working ◽  
Cyclic Behavior ◽  
Shape Memory Alloy Wire ◽  
Alloy Wire

Fatigue properties of a TiNi shape-memory alloy wire subjected to bending with various strain ratios

2003 ◽  
Vol 217 (2) ◽  
pp. 93-99 ◽  
Author(s):  
Y Furuichi ◽  
H Tobushi ◽  
T Ikawa ◽  
R Matsui
Keyword(s):  
Fatigue Life ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Strain Ratio ◽  
Fatigue Properties ◽  
Test Machine ◽  
Shape Memory Alloy Wire ◽  
Alloy Wire ◽  
Rotating Bending ◽  
Alternating Bending

A fatigue-test machine for alternating bending of a wire under strain-controlled conditions was developed. Bending-fatigue tests on a TiNi shape-memory alloy wire were then performed for various strain ratios. The results obtained can be summarized as: (1) the fatigue life curves under alternating bending and pulsating bending, as expressed by the relationship between maximum strain and the number of cycles to failure, systematically follow the order of strain ratio; (2) the larger the strain ratio, the longer the fatigue life; (3) the fatigue life under rotating bending is shorter than that under alternating bending; (4) the increase in temperature during cyclic bending becomes larger in the order: rotating bending, alternating bending, pulsating bending. The fatigue life decreases in proportion to the increase in temperature; and (5) the fatigue limit of strain for alternating bending, pulsating bending and rotating bending is in the region of R-phase transformation.

Cyclic Deformation and Fatigue of a TiNi Shape-Memory Alloy Wire Subjected to Rotating-Bending

1997 ◽  
Author(s):  
H. Tobushi ◽  
T. Hachisuka ◽  
T. Hashimoto ◽  
S. Yamada
Keyword(s):  
Fatigue Life ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Rotational Speed ◽  
Cyclic Deformation ◽  
Rhombohedral Phase ◽  
Shape Memory Alloy Wire ◽  
Alloy Wire ◽  
Deformation Properties ◽  
Rotating Bending

Abstract The cyclic deformation and fatigue of a TiNi shape-memory alloy wire was studied by carrying out rotating-bending fatigue tests at various strain amplitudes, temperatures and rotational speeds in air and in water. The results were summarized as follows: (1) for strain amplitudes in the rhombohedral-phase transformation region, the fatigue life was longer than 107 cycles and the deformation properties did not change under cyclic deformation; (2) for the strain amplitudes in the martensitic transformation region, the fatigue life was shorter than 105 cycles and the higher the temperature, the shorter was the fatigue life; (3) the rotational speed did not affect the fatigue life in water but a higher rotational speed led to a shorter fatigue life in air.

Improvement of Corrosion Fatigue Strength for TiNi Shape Memory Alloy

2016 ◽  
Vol 725 ◽  
pp. 389-393
Author(s):  
Kazuki Yamada ◽  
Ryosuke Matsui
Keyword(s):  
Fatigue Life ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Thermal Oxidation ◽  
Corrosion Fatigue ◽  
Passive Layer ◽  
Treatment Technique ◽  
Shape Memory Alloy Wire ◽  
Oxidation Treatment ◽  
Alloy Wire

In this study, we enhanced the corrosion fatigue life of a TiNi shape-memory alloy wire using a thermal oxidation treatment technique that can generate a passive layer on the wire surface. We followed the following procedure for the thermal oxidation treatment. First, the as-received material with an oxide film was mechanically polished to remove the film using an abrasive paper and a buffing compound. Second, the material was heat-treated in an electrical furnace filled with an N2-20 vol% O2 gas for 1 h at 673 K. Subsequently, the material was allowed to cool in the furnace. The results of this treatment are summarized as follows. (1) A passive layer was uniformly generated on the surface of the TiNi shape-memory alloy wire via thermal oxidation on a macroscopic scale; this significantly improved its corrosion resistance. (2) Thermal oxidation extended the corrosion fatigue life of the treated material more compared with HT in air. In addition, we found that the layer generated via the thermal oxidation treatment can maintain adhesion to the base material even when subjected to a bending strain greater than 1%.

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