Weldable, crack-resistant co-based alloy and overlay method

Abstract

An alloy for imparting wear- and corrosion-resistance to a metal component wherein the alloy comprises between about 0.12 wt % and about 0.7 wt % C, between about 20 wt % and about 30 wt % Cr, between about 10 wt % and about 15 wt % Mo, between about 1 wt % and about 4 wt % Ni, and balance of Co.

What is claimed is: 
     
         1 . A wear- and corrosion-resistant Co—Cr—Mo alloy comprising between about 0.12 wt % and about 0.7 wt % C, between about 20 wt % and about 30 wt % Cr, between about 10 wt % and about 15 wt % Mo, between about 1 wt % and about 4 wt % Ni, and balance of Co. 
     
     
         2 . The alloy of  claim 1  wherein the alloy has a hypoeutectic microstructure. 
     
     
         3 . The alloy of  claim 1  wherein the alloy has an electron vacancy number between about 2.25 and about 2.80 as calculated using SAE specification AS5491 (Revision B). 
     
     
         4 . The alloy of  claim 1  wherein the alloy has an electron vacancy number between about 2.32 and about 2.75 as calculated using SAE specification AS5491 (Revision B). 
     
     
         5 . The alloy of  claim 1  comprising between about 0.45 wt % and about 0.65 wt % C, between about 21 wt % and about 27 wt % Cr, between about 2 wt % and about 4 wt % Ni, and less than about 0.25 wt % Si. 
     
     
         6 . The alloy of  claim 1  comprising between about 0.50 wt % and about 0.60 wt % C, between about 23 wt % and about 25 wt % Cr, between about 2.7 wt % and about 3.7 wt % Ni, and less than about 0.25 wt % Si. 
     
     
         7 . The alloy of  claim 1  comprising, by approximate weight %: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   C 
                   0.12-0.7  
                 
                     
                   Cr 
                   20-30 
                 
                     
                   Mo 
                   10-15 
                 
                     
                   Ni 
                   1-4 
                 
                     
                   Si 
                   up to about 1 
                 
                     
                   Mn 
                   up to about 1 
                 
                     
                   Fe 
                   up to about 1 
                 
                     
                   W 
                   up to about 1 
                 
                     
                   B + Cu 
                   up to about 3 
                 
                     
                   Co 
                   Balance 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         8 . The alloy of  claim 7  wherein the alloy has an electron vacancy number between about 2.25 and about 2.80 as calculated using SAE specification AS5491 (Revision B). 
     
     
         9 . The alloy of  claim 7  wherein the Co—Cr—Mo alloy has an electron vacancy number between about 2.32 and about 2.75 as calculated using SAE specification AS5491 (Revision B). 
     
     
         10 . The alloy of  claim 7  wherein the alloy has a hypoeutectic microstructure. 
     
     
         11 . The alloy of  claim 1  wherein the alloy is in the form of powder, rod, casting, consumable electrode, or solid or tubular wire. 
     
     
         12 . The alloy of  claim 1  wherein the alloy is in the form of a metal powder for use in forming a wear- and corrosion-resistant overlay on a metal substrate. 
     
     
         13 . The alloy of  claim 1  wherein the alloy is in the form of a tubular wire for use in forming a wear- and corrosion-resistant overlay on a metal substrate, the wire comprising a sheath and metal powder therein, wherein the composite make-up of the sheath and powder comprises between about 0.12 wt % and about 0.7 wt % C, between about 20 wt % and about 30 wt % Cr, between about 10 wt % and about 15 wt % Mo, between about 1 wt % and about 4 wt % Ni, and balance of Co. 
     
     
         14 . The alloy of  claim 11  wherein the alloy has an electron vacancy number between about 2.25 and about 2.80 as calculated using SAE specification AS5491 (Revision B). 
     
     
         15 . The alloy of  claim 11  wherein the alloy has a hypoeutectic microstructure. 
     
     
         16 . The alloy of  claim 15  wherein The method of  claim 11  wherein the alloy microstructure consists essentially of a face-centered cubic Co-based phase and a M 7 C 3  primary carbide phase. 
     
     
         17 . The alloy of  claim 14  wherein the alloy has a hypoeutectic microstructure. 
     
     
         18 . The alloy of  claim 12  wherein the alloy has an electron vacancy number between about 2.25 and about 2.80 as calculated using SAE specification AS5491 (Revision B). 
     
     
         19 . The alloy of  claim 12  wherein the alloy has a hypoeutectic microstructure. 
     
     
         20 . The alloy of  claim 1  wherein the alloy is a weld overlay on a metallic component wherein the weld overlay surface area is greater than 1 m 2  and has a thickness between about 50 microns and 10 mm.