Chromium free hardfacing materials

Abstract

Disclosed are embodiments of Fe-based alloys for use as a hardfacing material having high hardness while avoiding the use of chromium. The alloys can be twin arc or thermally sprayed as coatings on different types of equipment. In some embodiments, the alloys can be readable even after heating of the alloys.

What is claimed is: 
     
         1 . A work piece having at least one surface, the work piece comprising:
 a coating applied to the at least one surface, the coating comprising an Fe-based alloy having substantially no chromium, having substantially no carbides, and having substantially no borides;   wherein the alloy comprises a Vickers hardness of at least 500 and an adhesion strength of at least 5,000 psi.   
     
     
         2 . The work piece of  claim 1 , wherein the coating comprises Fe and, in weight percent:
 B: about 0-4;   C: about 0-0.25;   Si: about 0-15;   Mn: about 0 to 25;   Mo: about 0-29;   Nb: about 0-2;   Ta: about 0-4;   Ti: about 0-4;   V: about 0-10;   W: about 0-6;   Zr: about 0-10;   wherein B+C+Si is about 4-15; and   wherein (Mo+Mn+Nb+Ta+Ti+V+W+Zr) is about 5 to 38.   
     
     
         3 . The work piece of  claim 1 , wherein the coating comprises Fe and in weight percent:
 C: about 0 to 0.25;   Mn: about 5 to 19;   Mo: about 7 to 23;   Ni: about 0 to 4; and   Si: about 5 to 10.   
     
     
         4 . The work piece of  claim 1 , wherein the coating comprises one or more of the following compositions in weight percent:
 Fe, Mn: about 5, Mo: about 13, Si: about 10, Al: about 2; or   Fe, Mn: about 5, Mo: about 7, Si: about 10, Al: about 2.   
     
     
         5 . The work piece of  claim 1 , wherein the coating is non-magnetic and the coating thickness can be accurately measured with an Elcometer™ thickness gauge or similar device after it has been exposed to temperatures exceeding about 1100 K for 2 hours or more and then slow cooled at a rate of 10K/s or less. 
     
     
         6 . The work piece of  claim 1 , wherein the coating is amorphous. 
     
     
         7 . The work piece of  claim 1 , wherein the coating is nanocrystalline, as defined by having a grain size of 100 nm or less. 
     
     
         8 . The work piece of  claim 1 , wherein the coating is applied via a thermal spray process. 
     
     
         9 . The work piece of  claim 1 , wherein the coating is applied via a twin wire arc spray process. 
     
     
         10 . The work piece of  claim 1 , wherein the work piece is a yankee dryer. 
     
     
         11 . The work piece of  claim 1 , wherein the work piece is a roller used in a paper making machine. 
     
     
         12 . An article of manufacture comprising:
 an Fe-based coating having substantially no chromium;   wherein the coating possesses a melting temperature of 1500K or below;   wherein the coating possesses a large atom concentration of at least 5 atom %, large atoms being of the group consisting of Mn, Mo, Nb, Ta, Ti, V, W, and Zr; and   wherein the coating is a primarily single phase fine-grained structure of either martensite, ferrite, or austenite.   
     
     
         13 . The article of manufacture of  claim 12 , wherein the coating comprises, in weight percent:
 B: about 0-4;   C: about 0-0.25;   Si: about 0-15;   Mn: about 0 to 25;   Mo: about 0-29;   Nb: about 0-2;   Ta: about 0-4;   Ti: about 0-4;   V: about 0-10;   W: about 0-6;   Zr: about 0-10;   wherein B+C+Si is about 4-15; and   wherein (Mo+Mn+Nb+Ta+Ti+V+W+Zr) is about 5 to 38.   
     
     
         14 . The article of manufacture of  claim 12 , wherein the coating comprises Fe and in weight percent:
 C: about 0 to 0.25;   Mn: about 5 to 19;   Mo: about 7 to 23;   Ni: about 0 to 4; and   Si: about 5 to 10.   
     
     
         15 . The work piece of  claim 12 , wherein the coating comprises one or more of the following compositions in weight percent:
 Fe, Mn: about 5, Mo: about 13, Si: about 10, Al: about 2; or   Fe, Mn: about 5, Mo: about 7, Si: about 10, Al: about 2.   
     
     
         16 . The article of manufacture of  claim 12 , wherein the coating is non-magnetic and the coating thickness can be accurately measured with an Elcometer™ thickness gauge or similar device after it has been exposed to temperatures exceeding about 1100 K for 2 hours or more and then slow cooled at a rate of 10K/s or less. 
     
     
         17 . The article of manufacture of  claim 12 , wherein the coating comprises a Vickers hardness of at least 500 and an adhesion strength of at least 5,000 psi. 
     
     
         18 . The article of manufacture of  claim 12 , wherein the coating is applied via the twin wire arc spray process. 
     
     
         19 . The article of manufacture of  claim 12 , wherein the coating is amorphous. 
     
     
         20 . The article of manufacture of  claim 12 , wherein the coating is nanocrystalline, as defined by having a grain size of 100 nm or less. 
     
     
         21 . The article of manufacture of  claim 12 , wherein the coating is applied via a thermal spray process. 
     
     
         22 . The article of manufacture of  claim 12 , wherein the coating is applied onto a roller used in a paper making machine. 
     
     
         23 . The article of manufacture of  claim 12 , wherein the coating is applied onto a Yankee Dryer. 
     
     
         24 . The article of manufacture of  claim 12 , wherein the coating is applied onto a boiler tube. 
     
     
         25 . A work piece having at least one surface, the work piece comprising:
 a coating applied to the at least one surface, the coating comprising an Fe-based alloy having less than 1 wt. % chromium, less than 5 vol. % carbides, and less than 5 vol. % borides;   wherein the alloy comprises a Vickers hardness of at least 500 and an adhesion strength of at least 5,000 psi.   
     
     
         26 . The work piece of  claim 25 , wherein the alloy has less than 1 vol. % carbides and less than 1 vol. % borides.