Modified flux system in cored electrode

Abstract

A cored electrode having reduced moisture pick-up properties and which forms a weld bead with low diffusible hydrogen in a gas shielded electric arc welding process. The cored electrode includes a metal sheath and a fill composition. The fill composition includes titanium dioxide, slag forming agent and a sodium-silica-titanate compound.

What is claimed is: 
     
         1 . A method of forming a weld bead having a low diffusible hydrogen content by use of an electrode having reduced moisture pick-up comprising:
 providing a cored electrode that includes a metal sheath and a fill composition, said fill composition including titanium dioxide, a slag forming agent and a moisture resistant compound, said moisture resistant compound comprising a sodium-silico-titanate compound, wherein said sodium-silico-titanate compound is formed of a combination of a titanium compound, a potassium compound, a sodium compound and colloidal silica, said moisture resistant compound having an average particle size of 30-250 mesh, said moisture resistant compound including over 50 weight percent titanium compound, said moisture resistant compound having a weight ratio of sedum compound to potassium compound of about 1.1-5:1, said moisture resistant compound including at least about 1 weight percent colloidal silica, said colloidal silica having an average particle size of less than about 40 nm; and,   at least partially melting said cored electrode by an electric current to cause said melted portion of said cored electrode to be deposited on a workpiece.   
     
     
         2 . The method as defined in  claim 1 , including the step of
 directing a shielding gas to said workpiece to at least partially shield said melted portion of said cored electrode being deposited on a workpiece.   
     
     
         3 . The method as defined in  claim 2 , wherein
 said shielding gas includes argon, carbon dioxide or mixtures thereof.   
     
     
         4 . The method as defined in  claim 1 , wherein
 said titanium dioxide minus any titanium dioxide in said moisture resistant compound is about 2-40 weight percent of said fill composition.   
     
     
         5 . The method as defined in  claim 2 , wherein
 said titanium dioxide minus any titanium dioxide in said moisture resistant compound is about 2-40 weight percent of said fill composition.   
     
     
         6 . The method as defined in  claim 1 , wherein
 said slag forming agent constitutes about 10-50 weight percent of said fill composition.   
     
     
         7 . The method as defined in  claim 5 , wherein
 said slag forming agent constitutes about 10-50 weight percent of said fill composition.   
     
     
         8 . The method as defined in  claim 1 , wherein
 said slag forming agent includes a metal oxide.   
     
     
         9 . The method as defined in  claim 7 , wherein
 a majority of said slag forming agent includes said metal oxide.   
     
     
         10 . The method as defined in  claim 1 , wherein
 said moisture resistant compound constitutes about 1-40 weight percent of said fill composition.   
     
     
         11 . The method as defined in  claim 9 , wherein
 said moisture resistant compound constitutes about 1-40 weight percent of said fill composition.   
     
     
         12 . The method as defined in  claim 1 , including
 a metal alloying agent, said metal alloying agent including aluminum, magnesium, silicon, titanium, and mixtures thereof.   
     
     
         13 . The method as defined in  claim 1 , wherein said fill composition includes: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   TiO 2   
                   2-50% 
                 
                     
                   Sodium-silico-titanate compound 
                   1-55% 
                 
                     
                   Slag forming Agent 
                   1-60% 
                 
                     
                   Metal Alloying Agent 
                   0-70% 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
       
     
     
         14 . The method as defined in  claim 1 , wherein said fill composition includes: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   TiO 2   
                    3-40% 
                 
                     
                   Sodium-silico-titanate compound 
                    1-55% 
                 
                     
                   Slag forming Agent 
                   20-50% 
                 
                     
                   Metal Alloying Agent 
                    0-55% 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
       
     
     
         15 . The method as defined in  claim 1 , wherein said moisture resistant compound includes by weight percent: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   TiO 2   
                   60-90%  
                 
                     
                   Sodium silicate 
                   1-20% 
                 
                     
                   Potassium silicate 
                   1-15% 
                 
                     
                   Sodium compound 
                   1-20% 
                 
                     
                   Colloidal Silica 
                   1-10% 
                 
                     
                   Other components 
                   0-5%  
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         16 . The method as defined in  claim 15  wherein
 said moisture resistant compound having reduced moisture pick-up such that the moisture pick-up of said moisture resistant compound over a 96 hour period at 80° F. and 80% relative humidity is less than about 0.2% for particles having an average particle size of 40-200 mesh. 
 
     
     
         17 . The method as defined in  claim 15  wherein said moisture resistant compound includes by weight percent: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   TiO 2   
                   70-90% 
                 
                     
                   Sodium silicate 
                    4-15% 
                 
                     
                   Potassium silicate 
                    1-10% 
                 
                     
                   Sodium carbonate 
                    3-16% 
                 
                     
                   Colloidal Silica 
                   2-6% 
                 
                     
                   Other components 
                   0-1% 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
               
            
           
         
       
     
     
         18 . The method as defined in  claim 17  wherein said moisture resistant compound includes by weight percent: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   TiO 2   
                   70-80%  
                 
                     
                   Sodium silicate 
                   3.5-10%   
                 
                     
                   Potassium silicate  
                   1.5-6%   
                 
                     
                   Sodium carbonate 
                    5-15% 
                 
                     
                   Colloidal Silica 
                   2-5%  
                 
                     
                   Other components 
                    0-0.5%