Hard weld overlays resistant to re-heat cracking

Abstract

A hard weld overlay which is resistant to cracking when re-heated, and a method for designing such alloys, is disclosed. The alloys are able to resist re-heat cracking through prevention of the precipitation and/or growth of embrittling carbide, borides, or borocarbides at elevated temperatures. In one embodiment, the thermodynamics of the alloy system possess only primary carbides and secondary ferrite carbides.

1 . (canceled) 
     
     
         2 . A hardfacing weld deposit comprising:
 a hardness of at least 60 HRC; and   a microstructure comprising:
 an iron-based matrix; and 
 carbides and/or borides; 
   wherein the carbides and/or borides comprise only carbides and/or borides which precipitate prior to solidification of the iron-based matrix.   
     
     
         3 . The deposit of  claim 2 , wherein the carbides and/or borides are selected from the group consisting of titanium boride, niobium carbide, chromium boride, iron-chromium boride, and combinations thereof 
     
     
         4 . The deposit  claim 2 , wherein the deposit does not form additional carbides or borides when re-heated to a range of 800° C. to 1300° C. for 1 s to 180 s. 
     
     
         5 . The deposit of  claim 2 , wherein the deposit does not form additional carbides or borides when re-heated to a range of 900° C. to 1200° C. for 1 s to 180 s. 
     
     
         6 . The deposit of  claim 2 , wherein the deposit does not form additional carbides or borides when re-heated to a range of 1000° C. to 1100° C. for 1 s to 180 s. 
     
     
         7 . The deposit of  claim 2 , wherein the deposit comprises at least one of: 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 4.54 Si 0.59 Ti 0.39 V 0.54 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 6 Si 0.59 Ti 1 V 0.54 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 6 Si 0.59 Ti 1 V 2 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 4.5 Si 0.59 Ti i V 0.54 ; 
       Fe ba1 C 1.2 B 2 Mn 1 Si 1.1 Ni 0.07 Cr 8.33 Mo 3.33 V 0.5 W 0.07 Ti 1.83 Nb 4 ; and 
       Fe ba1 C 1 B 2.5 Mn 2 Si 1.1 Ni 0.1 Cr 8.73 Mo 1 V 0.03 W 0.03 Ti 1.91 Nb 4.47 . 
     
     
         8 . A hardfacing weld deposit comprising:
 a hardness of at least 60 HRC; and   a stable carbide and/or boride structure;   wherein a mole fraction of the stable carbide and/or boride structure does not change by more than 25% when reheated.   
     
     
         9 . The deposit of  claim 8 , wherein the stable carbide and/or boride structure in the deposit does not change when re-heated to a range of 800° C. to 1300° C. for 1 s to 180 s. 
     
     
         10 . The deposit of  claim 8 , wherein the mole fraction of the stable carbide and/or boride structure does not change by more than 10% when reheated. 
     
     
         11 . The deposit of  claim 8 , wherein the mole fraction of the stable carbide and/or boride structure does not change by more than 5% when reheated. 
     
     
         12 . The deposit of  claim 8 , wherein the deposit further comprises an iron-based matrix, and the deposit possesses a carbide and/or boride thermodynamic stability such that a mole fraction of the carbides and/or borides does not change by more than 25% over a temperature range between room temperature and a solidification temperature of the iron-based matrix. 
     
     
         13 . The deposit of  claim 8 , wherein the deposit further comprises an iron-based matrix, and the deposit possesses a carbide and/or boride thermodynamic stability such that any carbides and/or borides do not form at temperatures above the solidification temperature of the iron-based matrix, and are only stable at temperatures below a re-heat temperature range. 
     
     
         14 . The deposit of  claim 13 , wherein the re-heat temperature range is about 800° C. to 1300° C. 
     
     
         15 . The deposit of  claim 13 , wherein the re-heat temperature range is about 900° C. to 1200° C. 
     
     
         16 . The deposit of  claim 13 , wherein the re-heat temperature range is about 1000° C. to 1100° C. 
     
     
         17 . The deposit of  claim 8 , wherein the deposit comprises at least one of: 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 4.54 Si 0.59 Ti 0.39 V 0.54 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 6 Si 0.59 Ti 1 V 0.54 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 6 Si 0.59 Ti 1 V 2 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 4.5 Si 0.59 Ti i V 0.54 ; 
       Fe ba1 C 1.2 B 2 Mn 1 Si 1.1 Ni 0.07 Cr 8.33 Mo 3.33 V 0.5 W 0.07 Ti 1.83 Nb 4 ; and 
       Fe ba1 C 1 B 2.5 Mn 2 Si 1.1 Ni 0.1 Cr 8.73 Mo 1 V 0.03 W 0.03 Ti 1.91 Nb 4.47 . 
     
     
         18 . A hardfacing weld deposit comprising:
 a hardness of at least 60 HRC; and   carbides and/or borides;   wherein the carbides and/or borides comprise an iron concentration of 50 wt. % or less.   
     
     
         19 . The deposit of  claim 18 , wherein the carbides and/or borides are selected from the group consisting of niobium carbide, titanium boride, chromium boride, tungsten carbide, molybdenum boride, and vanadium carbide, and combinations thereof. 
     
     
         20 . A hardfacing weld deposit comprising:
 a hardness of at least 60 HRC; and   an austenite to ferrite transition temperature which is outside a re-heat temperature range.   
     
     
         21 . The deposit of  claim 20 , wherein the re-heat temperature range is about 800° C. to 1300° C. 
     
     
         22 . The deposit of  claim 20 , wherein the re-heat temperature range is about 900° C. to 1200° C. 
     
     
         23 . The deposit of  claim 20 , wherein the re-heat temperature range is about 1000° C. to 1100° C. 
     
     
         24 . The deposit of  claim 20 , wherein the deposit comprises at least one of: 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 4.54 Si 0.59 Ti 0.39 V 0.54 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 6 Si 0.59 Ti 1 V 0.54 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 6 Si 0.59 Ti 1 V 2 ; 
       Fe ba1 B 1.45 C 0.91 Cr 4.82 Mn 1.01 Mo 3.22 Nb 4.5 Si 0.59 Ti i V 0.54 ; 
       Fe ba1 C 1.2 B 2 Mn 1 Si 1.1 Ni 0.07 Cr 8.33 Mo 3.33 V 0.5 W 0.07 Ti 1.83 Nb 4 ; and 
       Fe ba1 C 1 B 2.5 Mn 2 Si 1.1 Ni 0.1 Cr 8.73 Mo 1 V 0.03 W 0.03 Ti 1.91 Nb 4.47 .