Method for applying hardfacing to a matrix substrate of a drill bit
View Patent ↗A method for hardfacing a drill bit includes applying a hardfacing material to a matrix metal forming the substrate of the drill bit. The hardfacing material is applied using a plasma arc welding process. A metallurgical bond is formed between the matrix metal and the hardfacing material. The matrix metal may include tungsten carbide and a braze filler metal.
1. A method for reinforcing a drill bit defining a gauge portion and having at least one blade defining a face and a backside, having a plurality of cutter pockets formed therein, and having a web portion formed between adjacent cutter pockets, comprising:
applying a hardfacing material, using a plasma arc welding process, to a substrate of the at least one blade, the substrate comprising a matrix metal, the hardfacing material applied to the web portion of the at least one blade;
forming a metallurgical bond between the matrix metal and the hardfacing material; and
after forming the metallurgical bond, securing a plurality of polycrystalline diamond compact cutters into the respective cutter pockets.
2. The method of claim 1 wherein securing the plurality of polycrystalline diamond compact cutters comprises brazing the cutters into the respective cutter pockets.
3. The method of claim 1 wherein the matrix metal comprises tungsten carbide.
4. The method of claim 3 wherein the matrix metal comprises a braze filler metal.
5. The method of claim 4 wherein the braze filler metal is selected from a group consisting of manganese, nickel, zinc, and copper.
6. The method of claim 1 wherein the hardfacing material comprises tungsten carbide and is harder than the matrix metal.
7. The method of claim 1 wherein the hardfacing material is also applied to the face of the at least one blade.
8. The method of claim 7 wherein the hardfacing material is also applied to the backside of the at least one blade.
9. The method of claim 8 wherein the hardfacing material is also applied to the gauge portion.
10. The method of claim 6 wherein the hardfacing material comprises spherical tungsten carbide in a binder.
11. The method of claim 10 wherein the binder is selected from a group consisting of nickel, copper, boron, and zinc.
12. The method of claim 1 wherein the plasma arc welding process comprises heating a tip of an electrode within a plasma arc welding torch to approximately 30,000 degrees Fahrenheit.
13. The method of claim 1 wherein the plasma arc welding process comprises forcing plasma through an arc-constricting nozzle of a plasma arc welding torch.
14. The method of claim 1 wherein the plasma arc welding process includes an electrode comprising tungsten.
15. The method of claim 14 wherein the electrode comprises sintered tungsten.
16. The method of claim 1 wherein the plasma arc welding process is a transferred arc process.