K. Iwasaki, Furukawa Techno Material, Hiratsuka, Japan; T. Tanaka, Furukawa Techno Material Co., Ltd., Hiratsuka-city, Kanagawa pref, Japan
The features of regular Ni-Ti based alloy including excellent recovery from large deformation (super-elasticity) and corrosion resistance, result in it often being chosen for medical devices, such as GUIDE-WIRE application. However, the super-elastic alloy has a yield point on the stress-strain curve; stress is not increased even if more strain is given, when exceeding the yield point, so in this case the wire may not exhibit high PUSH ABILITY.
In contrast the new wire (FHP-NT) has the following 4 features:
- high stiffness like a stainless steel,
- wide deformation range like super-elastic,
- superior straightness,
- no yield point on s/s curve.
Furukawa produce the new FHP-NT wire by mechanical straightening of a cold drawn Ni rich -Ti based alloy and perform measurement of straightness, tensile testing, DSC curve and electrical resistance. FHP-NT exhibits; no yield point on the stress-strain curve, increased linear stress up to 1400MPa at 4% strain and less than 0.15% residual strain after loading to 4% strain. The wire also shows stable characteristics over a wide temperature range, therefore its physical properties do not change according to the environment conditions. Consequently there is no stress-induced Martensitic transformation in macro-view and no visible peak on DSC chart.
Summary: Furukawa produce the new FHP-NT wire has high stiffness like a stainless steel,
wide deformation range like super-elastic, superior straightness, no yield point on s/s curve by mechanical straightening of a cold drawn Ni rich -Ti based alloy.
