Alloys for hardbanding weld overlays

Abstract

Disclosed herein are iron-based alloys having a microstructure comprising a fine-grained ferritic matrix and having a 60+ Rockwell C surface, wherein the ferritic matrix comprises <10 μm carbide precipitates. Also disclosed are methods of welding comprising forming a crack free hardbanding weld overlay coating with such an iron-based alloy. Also disclosed are families of alloys capable of forming crack-free weld overlays after multiple welding passes.

1 - 23 . (canceled) 
     
     
         24 . A composition of matter comprising:
 Fe;   between 4-6 wt. % Cr;   between 0.8-1.2 wt. % Mn;   between 4-5 wt. % Nb;   between 0-1 wt. % V;   between 0.6-1.1 wt. % C;   between 0.1-0.5 wt. % Ti; and   between 0.4-0.75 wt. % Si.   
     
     
         25 . The composition of matter of  claim 24 , further comprising:
 B in an amount of 2.25 wt. % or less; and   Mo in an amount of 4 wt. % or less.   
     
     
         26 . The composition of matter of  claim 24 , wherein the composition is a welding wire. 
     
     
         27 . The composition of matter of  claim 24 , wherein the composition is a weld. 
     
     
         28 . An alloy comprising:
 Fe;   between 4-6 wt. % Cr;   between 0.8-1.2 wt. % Mn;   between 4-5 wt. % Nb;   between 0-1 wt. % V;   between 0.6-1.1 wt. % C;   between 0.1-0.5 wt. % Ti; and   between 0.4-0.75 wt. % Si.   
     
     
         29 . The alloy of  claim 28 , further comprising:
 B in an amount of 2.25 wt. % or less; and   Mo in an amount of 4 wt. % or less.   
     
     
         30 . The alloy of  claim 28 , wherein the alloy has a Rockwell C hardness greater than 50. 
     
     
         31 . The alloy of  claim 30 , wherein the alloy has a Rockwell C hardness greater than 55. 
     
     
         32 . The alloy of  claim 28 , wherein the alloy has a microstructure comprising a fine-grained matrix, wherein the matrix comprises Nb-carbide precipitates having sizes less than 10 μm and hard precipitates having grain sizes less than 10 μm. 
     
     
         33 . The alloy of  claim 28 , wherein the alloy is capable of being deposited as a weld overlay coating. 
     
     
         34 . The alloy of  claim 28 , wherein the alloy is capable of being deposited using a MIG welding technique on a tool joint. 
     
     
         35 . The alloy of  claim 28 , wherein the alloy is capable of being deposited crack-free when deposited on a substrate that is pre-heated to at least 500° F. 
     
     
         36 . The alloy of  claim 28 , wherein the alloy is capable of being welded in two layers onto a 4137 6⅝″ O.D. tool joint to achieve a total weld thickness of at least 8/32″ without cracking. 
     
     
         37 . The alloy of  claim 36 , wherein the alloy is capable of being deposited as a 10/32″ thick double pass weld overlay without cracking. 
     
     
         38 . The alloy of  claim 36 , wherein the alloy exhibits a mass loss less than 0.3 g lost in ASTM G65 Procedure A.