Medical instrument for soft tissue and method for manufacture thereof

Abstract

Ferritic stainless steel was produced by the melting method. The ferritic stainless steel was worked to the shape of a medical device for living soft tissue to obtain a medical device body. The medical device body was brought into contact with gas including nitrogen at a 800° C. treatment temperature or more to make the ferritic stainless steel forming the medical device body absorb the nitrogen and transform at least part of the ferritic stainless steel to austenite.

1 . A method for producing a medical device for living soft tissue having: 
 a melting step of producing ferritic stainless steel by melting method,    a working step of working said ferritic stainless steel to the shape of a medical device for living soft tissue to obtain a medical device body, and    a nitrogen absorption step of bringing said medical device body into contact with a gas containing nitrogen at a predetermined treatment temperature or more to make said ferritic stainless steel forming said medical device body absorb nitrogen to transform at least part of said ferritic stainless steel to austenite.    
   
   
       2 . The method of production of a medical device for living soft tissue as set forth in  claim 1 , wherein said ferritic stainless steel has as main ingredients Fe in an amount of 50 to 90 wt %, Cr and/or Mn in amounts of 10 to 30 wt %, and Mo and/or Ti in amounts of 0 to 10 wt %.  
   
   
       3 . The method of production of a medical device for living soft tissue as set forth in  claim 1 , wherein said ferritic stainless steel has as main ingredients Fe in an amount of 65 to 80 wt %, Cr and/or Mn in amounts of 15 to 25 wt %, and Mo and/or Ti in amounts of 0 to 5 wt %.  
   
   
       4 . The method of production of a medical device for living soft tissue as set forth in  claim 1 , wherein said treatment temperature is in a temperature range of 800 to 1500° C.  
   
   
       5 . The method of production of a medical device for living soft tissue as set forth in  claim 1 , wherein said treatment temperature is in the temperature range of 1100 to 1300° C.  
   
   
       6 . The method of production of a medical device for living soft tissue as set forth in  claim 1 , wherein said ferritic stainless steel is made to contain nitrogen in an amount of at least 0.5 wt %.  
   
   
       7 . The method of production of a medical device for living soft tissue as set forth in  claim 1 , wherein said ferritic stainless steel is made to contain nitrogen in an amount of at least 0.8 wt %.  
   
   
       8 . The method of production of a medical device for living soft tissue as set forth in  claim 1 , wherein at least part of said ferritic stainless steel is transformed to austenite to form a two-phase structure of ferrite and austenite.  
   
   
       9 . The method of production of a medical device for living soft tissue as set forth in  claim 1 , wherein all of said ferritic stainless steel is transformed to austenite.  
   
   
       10 . The medical device for living soft tissue produced by a method of production of a medical device for living soft tissue as set forth in  claim 1 .  
   
   
       11 . The method of production of a medical device for living soft tissue as set forth in  claim 2 , wherein said treatment temperature is in a temperature range of 800 to 1500° C.  
   
   
       12 . The method of production of a medical device for living soft tissue as set forth in  claim 2 , wherein said treatment temperature is in the temperature range of 1100 to 1300° C.  
   
   
       13 . The method of production of a medical device for living soft tissue as set forth in  claim 2 , wherein said ferritic stainless steel is made to contain nitrogen in an amount of at least 0.5 wt %.  
   
   
       14 . The method of production of a medical device for living soft tissue as set forth in  claim 2 , wherein said ferritic stainless steel is made to contain nitrogen in an amount of at least 0.8 wt %.  
   
   
       15 . The method of production of a medical device for living soft tissue as set forth in  claim 2 , wherein at least part of said ferritic stainless steel is transformed to austenite to form a two-phase structure of ferrite and austenite.  
   
   
       16 . The method of production of a medical device for living soft tissue as set forth in  claim 2 , wherein all of said ferritic stainless steel is transformed to austenite.  
   
   
       17 . The medical device for living soft tissue produced by a method of production of a medical device for living soft tissue as set forth in  claim 2.