Crack resistant hardfacing alloys
Embodiments of an alloy that can be resistant to cracking. In some embodiments, the alloy can be advantageous for use as a hardfacing alloys, in both a diluted and undiluted state. Certain microstructural, thermodynamic, and performance criteria can be met by embodiments of the alloys that may make them advantageous for hardfacing.
1. An article of manufacture for use as a feedstock for hardfacing weld overlay, wherein the article comprises:
an alloy having-a macro-hardness of 50 HRC or greater and a high resistance to stress cracking and hot tearing when welded as a single layer or over a worn existing hardfacing layer;
wherein a resultant hardfacing deposit of the alloy contains greater than 0 volume % grain boundary carbides and/or borides but less than 15 volume % grain boundary precipitates when present in a fully undiluted and a fully diluted state;
wherein the maximum eutectic carbide/boride phase fraction of the alloy is about 15 mole %;
wherein the minimum carbon level in the liquid of the alloy is about 0.5 wt. %; and
wherein the alloy comprises a majority of Fe and, in wt. %:
B: about 0.6-about 0.9;
C: about 0.75-about 1.25;
Cr: about 14.25-about 26; and
Nb+Ti+V: about 3.5-about 4.5.
2. The article of claim 1 , wherein the resultant hardfacing deposit of the alloy has high abrasion resistance as characterized by an ASTM G65A mass loss of less than 0.5 grams.
3. The article of claim 1 , wherein the resultant hardfacing deposit of the alloy contains both carbide and boride precipitates.
4. The article of claim 1 , wherein the resultant hardfacing deposit of the alloy contains greater than 0 volume % grain boundary carbides and/or borides but less than 15 volume % grain boundary precipitates.
5. The article of claim 1 , wherein the alloy further comprises, in wt. %:
Mn: about 1.1;
Mo: about 1; and
Si: about 0.5.
6. The article of claim 1 , wherein the resultant hardfacing deposit of the alloy is primarily martensitic.
7. The article of claim 1 , wherein the resultant hardfacing deposit of the alloy has a matrix comprising at least about 10% by volume martensite.
8. The article of claim 1 , wherein:
the maximum grain boundary formation temperature gap of the alloy is about 80K; and
the alloy comprises both carbides and borides, and the carbides are thermodynamically stable at a temperature equal to or greater than about 80K below the liquid temperature of the austenite or ferrite matrix phase.
9. The article of claim 1 , wherein the alloy comprises:
less than 10 mole % carbides and/or borides at 1300K;
at least one carbide and one boride phase at 1300K; and
eutectic carbides and/or borides at no less than 80K below the liquidus temperature of the ferritic or austenitic iron matrix phase.
10. The article of claim 1 , wherein the article is a welding wire.
11. The article of claim 1 , wherein the article is a powder.
12. The article of claim 1 , wherein the article is configured for application by thermal spray.
13. The article of claim 1 , wherein the article is configured for application by welding.
14. The article of claim 1 , wherein the article is configured for application by a casting process.