Systems and methods for dissimilar material welding

Abstract

A system is provided comprising a hardened stud body and an unhardened stud subunit coupled to the hardened stud body. The hardened stud body may comprise a first composition having by weight between 17% and 21% chromium, between 2.8% and 3.3% molybdenum, between 50% to 55% nickel, and between 4.75% and 5.5% niobium. The unhardened stud subunit may comprise a second composition having by weight between 20% and 23% chromium, between 8% and 10% molybdenum, at least 58% nickel, and between 3.15% and 4.15% niobium.

What is claimed is: 
     
         1 . A system comprising:
 a hardened stud body; and   an unhardened stud subunit coupled to the hardened stud body.   
     
     
         2 . The system of  claim 1 , wherein the hardened stud body comprises a first composition having by weight between 17% and 21% chromium, between 2.8% and 3.3% molybdenum, between 50% to 55% nickel, and between 4.75% and 5.5% niobium. 
     
     
         3 . The system of  claim 2 , wherein the unhardened stud subunit comprises a second composition having by weight between 20% and 23% chromium, between 8% and 10% molybdenum, at least 58% nickel, and between 3.15% and 4.15% niobium. 
     
     
         4 . The system of  claim 2 , wherein the first composition conforms to ASTM A1014/A1014M. 
     
     
         5 . The system of  claim 3 , wherein the second composition conforms to ASTM B444. 
     
     
         6 . The system of  claim 1 , wherein the hardened stud body is formed from an unhardened stud body and the unhardened stud subunit is coupled to the unhardened stud body. 
     
     
         7 . The system of  claim 6 , wherein the unhardened stud body undergoes a heat treatment to become the hardened stud body. 
     
     
         8 . The system of  claim 6 , wherein the unhardened stud subunit is at least one of friction welded, inertia bonded, explosive welded, resistance welded, laser welded, gas tungsten arc welded, or brazed to an unhardened stud body. 
     
     
         9 . The system of  claim 3 , wherein the unhardened stud subunit is coupled to a substrate. 
     
     
         10 . The system of  claim 9 , wherein the substrate comprises a third composition having by weight between 20% and 23% chromium, between 8% and 10% molybdenum, at least 58% nickel, and between 3.15% and 4.15% niobium. 
     
     
         11 . A method comprising:
 welding an unhardened stud body comprising a first composition to an unhardened stud subunit comprising a second composition, to form a stud having an unhardened subunit portion; and   heat treating the stud.   
     
     
         12 . The method of  claim 11 , wherein the first composition comprises by weight between 17% and 21% chromium, between 2.8% and 3.3% molybdenum, between 50% to 55% nickel, and between 4.75% and 5.5% niobium. 
     
     
         13 . The method of  claim 12 , wherein the second composition comprises by weight between 20% and 23% chromium, between 8% and 10% molybdenum, at least 58% nickel, and between 3.15% and 4.15% niobium. 
     
     
         14 . The method of  claim 12 , wherein the first composition conforms to ASTM A1014/A1014M. 
     
     
         15 . The method of  claim 13 , wherein the second composition conforms to ASTM B444. 
     
     
         16 . The method of  claim 11 , wherein the heat treating comprises a precipitation heat treatment. 
     
     
         17 . The method of  claim 11 , wherein welding the unhardened stud body to the unhardened stud subunit comprises at least one of friction welding, explosive welding, resistance welded, laser welding, or gas tungsten arc welding. 
     
     
         18 . The method of  claim 11 , wherein welding the stud to the substrate comprises capacitor discharge welding. 
     
     
         19 . The method of  claim 11 , wherein the substrate comprises a third composition having by weight between 20% and 23% chromium, between 8% and 10% molybdenum, at least 58% nickel, and between 3.15% and 4.15% niobium. 
     
     
         20 . The method of  claim 19 , further comprising welding the stud to a substrate, wherein a weld created by welding the stud to the substrate is located at least partially on the unhardened subunit portion.