Anti-galling nut assembly

Abstract

Described herein is a nut assembly including a nut and a fastener insert wherein at least one of the components is formed from a nitrogen strengthened stainless steel which is resistant to galling. In addition to reduced galling, fastener inserts formed from the nitrogen strengthened stainless steel exhibits good corrosion resistance and a yield strength which is almost twice that of fastener inserts formed from 304 type stainless steel.

What is claimed is:  
     
         1 . A nut assembly including a fastener insert and a nut having a barrel for receiving the insert, wherein at least one of the components selected for the fastener insert and nut is formed from a nitrogen strengthened stainless steel alloy comprising: 
 a) from about 0.05 to 0.15% carbon;    b) from about 5.0 to 12.0% manganese;    c) from about 2.0 to 6.0% silicon;    d) from about 12.0 to 20.0% chromium;    e) from about 6.0 to 12.0% nickel;    f) from about 0.02 to 0.8% nitrogen;    with the remainder being iron.    
     
     
         2 . The nut assembly of    claim 1    wherein said fastener insert is in the form of a helically coiled wire.  
     
     
         3 . The nut assembly of    claim 2    wherein said helically coiled wire has a substantially diamond shaped cross section.  
     
     
         4 . The nut assembly of    claim 2    wherein said helically coiled wire has about a 60° internal screw thread convolution.  
     
     
         5 . The nut assembly of    claim 1    wherein said helically coiled wire includes a selectively removable tang.  
     
     
         6 . The nut assembly of    claim 1    wherein said assembly is resistant to galling.  
     
     
         7 . The nut assembly of    claim 1    wherein said fastener insert includes at least one geometrically dissimilar convolution.  
     
     
         8 . The nut assembly of    claim 7    wherein said at least one geometrically dissimilar convolution is substantially hexagonal in shape.  
     
     
         9 . A nut assembly for use in association with a threaded fastener comprising: 
 a nut having an internal screw thread barrel; and    a fastener insert disposed within said barrel for receiving said threaded fastener;    wherein at least one of said nut and fastener insert is formed from a nitrogen strengthened stainless steel alloy which is resistant to galling.    
     
     
         10 . The nut assembly of    claim 9    wherein the fastener insert is formed from an alloy comprising: 
 a) from about 0.05 to 0.15% carbon;  
 b) from about 5.0 to 12.0% manganese;  
 c) from about 2.0 to 6.0% silicon;  
 d) from about 12.0 to 20.0% chromium;  
 e) from about 6.0 to 12.0% nickel;  
 f) from about 0.02 to 0.8% nitrogen;  
 with the remainder being iron.  
 
     
     
         11 . The nut assembly of    claim 9    wherein said fastener insert is a helically coiled wire.  
     
     
         12 . The nut assembly of    claim 10    wherein said fastener insert has a substantially diamond shaped cross section.  
     
     
         13 . The nut assembly of    claim 10    wherein said fastener insert has about a 60° internal screw thread convolution.  
     
     
         14 . The nut assembly of    claim 10    wherein said fastener insert includes a selectively removable tang.  
     
     
         15 . The nut assembly of    claim 10    wherein said assembly is resistant to galling.  
     
     
         16 . The nut assembly of    claim 10    wherein said fastener insert includes at least one geometrically dissimilar convolution.  
     
     
         17 . The nut assembly of    claim 16    wherein said at least one geometrically dissimilar convolution is substantially hexagonal in shape.  
     
     
         18 . The nut assembly of    claim 9    wherein said nut is formed from an alloy comprising: 
 a) from about 0.05 to 0.15% carbon;  
 b) from about 5.0 to 12.0% manganese;  
 c) from about 2.0 to 6.0% silicon;  
 d) from about 12.0 to 20.0% chromium;  
 e) from about 6.0 to 12.0% nickel;  
 f) from about 0.02 to 0.8% nitrogen;  
 with the remainder being iron.