Carbide-based hardfacing

Patent metadata

Field	Value
Publication number	US-10946465-B2
Application number	US-201515525021-A
Country	US
Kind code	B2
Filing date	Nov 6, 2015
Priority date	Nov 7, 2014
Publication date	Mar 16, 2021
Grant date	Mar 16, 2021

Abstract

One aspect of the disclosure provides an iron-based hardfacing layer which includes hard or wear resistant phases resulting at least in part from dissolution of silicon and/or boron carbide particles into a liquid iron-based metal during the fabrication process. In an embodiment, the hardfacing layer is formed by a fusion welding process in which carbide particles are added to the molten weld pool. In an example, the filler metal supplied to the welding process is a mild steel. In an embodiment, the hardness as measured at the surface of the hardfacing ranges from 40 to 65 HRC. In an example, the iron-based hardfacing layer also includes tungsten carbide particles.

First claim

We claim:

1. A hardfacing layer joined to at least a portion of a metal surface by a metal fusion bond, the hardfacing layer comprising a first region comprising a first iron-based material, wherein the first iron-based material further comprises:
silicon carbide and boron carbide, and wherein at least a portion of the first iron-based material comprises martensite and retained austenite,
wherein the hardness in the first region is from 55 to 65 Rockwell C (HRC) and wherein the martensite in the first region comprises high-carbon martensite; and

the hardfacing layer further comprising a second region interior to the first region, the second region comprising a second iron-based material, the second iron-based material further comprises:
silicon carbide and boron carbide, and wherein at least a portion of the second iron-based material comprises martensite and retained austenite,
wherein the hardness in the second region is from 40 to 55 Rockwell C (HRC) and wherein the martensite in the second region comprises low-carbon, lath martensite; and
such that high-carbon martensite and retained austenite is observed near a surface of the hardfacing layer, and lath martensite with retained austenite is observed at a junction of the hardfacing layer and the metal surface.

2. The hardfacing layer joined to at least a portion of a metal surface of claim 1 , wherein the metal surface is a tooth, blade, knife, flail, block, hammer, anvil, plate, tang, raiser, drum skin, pocket or screen of an article.

3. The hardfacing layer of claim 1 , wherein at least a portion of the first and second iron-based materials comprise a metal carbide and a metal boride.

4. The hardfacing layer of claim 1 , wherein the first and second iron-based materials comprise a metal carbide and an iron boride.

5. The hardfacing layer of claim 1 , wherein an average amount of boron in the first and second iron-based materials is from 1 wt % to 10 wt %; and an average amount of silicon in the first and second iron-based materials is from 1 wt % to 10 wt %.

6. The hardfacing layer of claim 1 , wherein the silicon carbide and boron carbide includes a mixture of approximately 50 vol. % boron carbide and 50 vol. % silicon carbide.

7. The hardfacing layer of claim 1 , wherein each of the first and second iron-based materials further includes tungsten carbide.

8. The hardfacing layer of claim 1 , wherein the first and second iron-based materials further include chromium carbide.

9. The hardfacing layer of claim 1 , wherein an average amount of chromium in the first and second iron-based material is less than 1 wt %.

10. The hardfacing layer of claim 1 , wherein the first and second iron-based materials further comprise chromium, an average amount of chromium present being from 7 wt % to 28 wt %.

11. A hardfacing layer joined to at least a portion of a metal surface by a metal fusion bond, the hardfacing layer comprising a first region comprising a first iron-based material, wherein the first iron-based material further comprises:
silicon carbide, and wherein at least a portion of the first iron-based material comprises martensite and retained austenite,
wherein the hardness in the first region is from 55 to 65 Rockwell C (HRC) and wherein the martensite in the first region comprises high-carbon martensite; and

the hardfacing layer further comprising a second region interior to the first region, the second region comprising a second iron-based material, the second iron-based material further comprises:
silicon carbide, and wherein at least a portion of the second iron-based material comprises martensite and retained austenite,
wherein the hardness in the second region is from 40 to 55 Rockwell C (HRC) and wherein the martensite in the second region comprises low-carbon, lath martensite; and
such that high-carbon martensite and retained austenite is observed near a surface of the hardfacing layer, and lath martensite with retained austenite is observed at a junction of the hardfacing layer and the metal surface.

12. The hardfacing layer of claim 11 , wherein an average amount of silicon present in the first and second iron-based materials is from 2 wt % to 10 wt %.

13. The hardfacing layer of claim 11 , wherein the first region comprises less than 10 vol % undissolved silicon carbide particles.

14. The hardfacing layer of claim 11 , wherein each of the first and second iron-based materials further includes tungsten carbide.

15. A hardfacing layer joined to at least a portion of a metal surface by a metal fusion bond, the hardfacing layer comprising a first region comprising a first iron-based material, wherein the first iron-based material further comprises:
boron carbide, and wherein at least a portion of the first iron-based material comprises martensite and retained austenite,
wherein the hardness in the first region is from 55 to 65 Rockwell C (HRC) and wherein the martensite in the first region comprises high-carbon martensite; and

the hardfacing layer further comprising a second region interior to the first region, the second region comprising a second iron-based material, the second iron-based material further comprises:
boron carbide, and wherein at least a portion of the second iron-based material comprises martensite and retained austenite,
wherein the hardness in the second region is from 40 to 55 Rockwell C (HRC) and wherein the martensite in the second region comprises low-carbon, lath martensite; and
such that high-carbon martensite and retained austenite is observed near a surface of the hardfacing layer, and lath martensite with retained austenite is observed at a junction of the hardfacing layer and the metal surface.

16. The hardfacing layer of claim 15 , wherein an average amount of boron in the first and second iron-based materials is from 2 wt % to 10 wt %.

17. The hardfacing layer of claim 15 , wherein the first region comprises less than 10 vol % undissolved B 4 C particles.

18. The hardfacing layer of claim 15 , wherein each of the first and second iron-based materials further includes tungsten carbide.

Assignees

• Vermeer Mfg Co

Inventors

• Muchtar Wanti
• Landon David
• Johnson Bjorn

Classifications

• B23K26/34

  Laser welding for purposes other than joining · CPC title

• Y10T428/12625

  Free carbon containing component · CPC title

• Y10T428/12924

  Fe-base has 0.01-1.7% carbon [i.e., steel] · CPC title

• Y10T428/12965

  Both containing 0.01-1.7% carbon [i.e., steel] · CPC title

• B23K35/308

  with Cr as next major constituent · CPC title