The NiTi based alloy wire, the production manner and the guide wire null stretch stress - for the catheter which uses the aforementioned

摘要

PROBLEM TO BE SOLVED: To provide an NiTi based alloy wire having excellent pushability, controllability and shape recoverability and particularly suitable to a guide wire for a catheter and to provide its production method. SOLUTION: This NiTi based alloy wire has no stress stage parts in a tensile stress-strain curve, further has a high apparent elastic modulus, has straightness by a drooping method of =10 mm/2 m and has a deformation angle of =8 deg. after the application of bending strain of 8.3% for 30 sec subsequently to its coiling around a half of a round bar at a room temperature. In the method for producing the NiTi based alloy wire, an NiTi based alloy wire rod subjected to cold wire drawing, in which the thickness of an oxidized film is =3 m is subjected to heat treatment of applying tension by 20 to 70% of its tensile strength at 300 to 450 deg.C for 5 sec to 1 min.