Precipitation hardenable austenitic steel

Abstract

The present invention relates to a stainless steel alloy, more precisely a highstrength stainless, precipitation hardenable, austenitic, stainless alloy, containing a well adjusted amount of aluminium and a high silicon content and which has the following composition (in weight-%): C 0-0.07 Si 0.5-3.0 N 0-0.1 Cr 15.0-20.0 Ni 7.0-12.0 Al 0.25-1.5 Cu 0<Cu<4.0 Mn 0-3.0 Mo 0-2.0 Ti 0-1.0 and the balance Fe together with normally occurring impurities and additives and a product that is reduced by cold working, especially drawing, without intermediate heat treatment, the strength of which increases by final heat treatment at 300° C. to 500° C. by not less than 14%, that shows a M d30 -value of between −55 and −100, a loss of force that is smaller than 3.0% at 1 N during 24 h and which is very suitable for use in spring applications, such as springs of round wire and strip steel and in medical applications, such as surgical and dental instruments.

1 . Product, manufactured from a high-strength austenitic stainless alloy, that it is precipitation hardenable and has the following composition (in weight-%): 
 C more than 0 to 0.035    Si 1    N>0-0.1    Cr about 17.5    Ni 9.0-10.0    Al 0.7-1.0    Cu 3    Mn 0.7-1.0    Mo>0-2.0    Ti>0-1.0    and the balance Fe together with normally occurring impurities and additives,    said alloy having been reduced by cold-working without an intermediate heat treatment followed by a final step of heating to a temperature of 300° C. to 500° C. to increase strength by at least 14%.    
   
   
       2 . A product of  claim 1 , which has loss of force which is smaller than 3.0% at 1400 N during 24 h.  
   
   
       3 . A product of  claim 1  in the form of wire, profiles and/or strip.  
   
   
       4 . A product of  claim 1  in the form of springs of round wire and strip steel.  
   
   
       5 . A product of  claim 1  in the form of surgical and dental instruments.  
   
   
       6 . A product of  claim 1 , which has loss of force which is smaller than 3.0% at 1400 N during 24 h.  
   
   
       7 . A product of  claim 1  in the form of wire, profiles and/or strip.  
   
   
       8 . A product of  claim 1  in the form of springs of round wire and strip steel.  
   
   
       9 . A product of  claim 1  in the form of surgical and dental instruments.  
   
   
       10 . Product, manufactured from a high-strength austenitic stainless alloy, that it is precipitation hardenable and has the following composition (in weight-%): 
 C more than 0 to 0.035    Si 1    N>0-0.1    Cr 17    Ni 9.0-10.0    Al 0.7-1.0    Cu 3    Mn 0.7-1.0    Mo>0-2.0    Ti>0-1.0    and the balance Fe together with normally occurring impurities and additives,    said alloy having been reduced by cold-working without an intermediate heat treatment followed by a final step of heating to a temperature of 300° C. to 500° C. to increase strength by at least 14%.