公开(公告)号：US09878366B2

公开(公告)日：2018-01-30

申请号：US14269968

申请日：2014-05-05

Applicant: DENTSPLY SIRONA INC.

Inventor： William B. Johnson

IPC: A61C5/02 ,  B21K5/02 ,  C21D1/26 ,  C21D9/00 ,  C21D9/56 ,  A61C5/42 ,  C22C19/03 ,  C22F1/00 ,  C22F1/10

CPC classification number: B21K5/02 ,  A61C5/42 ,  A61C2201/007 ,  C21D1/26 ,  C21D9/0068 ,  C21D9/56 ,  C21D2201/01 ,  C21D2211/001 ,  C21D2211/008 ,  C22C19/03 ,  C22F1/006 ,  C22F1/10 ,  Y10T29/49567

Abstract: A fatigue-resistant Nitinol instrument has a working portion in the deformed monoclinic martensitic state and an austenite finish temperature in the range of 40° to 60° C. Because the operating environment of the instrument is about 37° C., the working portion remains in the monoclinic martensitic state during its use. The relatively high austenite finish temperature and fatigue resistance is achieved by subjecting the nickel-titanium alloy to a final thermal heat treat in a temperature range of about 410° to 440° C. while the nickel-titanium alloy is under constant strain of about 3 to 15 kg. Further, the high austenite finish temperature is achieved without subjecting the alloy to thermal cycling to produce shape memory. Additionally, there are no intermediate processing steps occurring between obtaining a finished diameter of the wire or blank through cold working and the final thermal heat treat under constant strain.