I. During drilling in highly hard (rock hardness coefficient F14–16) and highly abrasive formations, the carbide teeth of down-the-hole drill bits are subjected to intense impact and cutting‑friction against the tough rock. Conventional manufacturing processes often result in carbide teeth with poor surface stress states, insufficient surface densification, and relatively low toughness. Under sustained loading, microcracks propagate rapidly, leading to premature failure modes such as tooth chipping, fracture, and excessive wear, ultimately rendering the drill bit unusable. Frequent replacement of drill bits not only significantly increases mining consumables costs but also severely disrupts continuous production operations.

Unlike conventional approaches that focus on marginal improvements in process parameters—such as optimizing alloy composition ratios or fine-tuning sintering conditions—this method employs post‑treatment of the alloy column‑tooth surface. By means of mechanical plastic modification, it optimizes the microstructure and stress state of the tooth’s surface layer, thereby fundamentally enhancing the wear resistance and fracture toughness of the alloy teeth. Its advantages are:

(1) There is no need to alter the alloy tooth substrate material; performance can be significantly enhanced through surface mechanical strengthening.

(2) Optimize the surface stress state by introducing stable residual compressive stresses, which effectively counteract the alternating tensile stresses imposed during drilling, inhibit the initiation and propagation of surface microcracks, enhance the fatigue‑impact resistance of alloy teeth, and prevent brittle fracture under transient impact loads.

(3) Enhance surface hardness and improve wear and corrosion resistance; mechanical strengthening can densify the porous microstructure on the alloy tooth surface, refine the carbide grain size, and form a dense, highly hardened strengthened layer on the tooth surface.

(4) Enhance fracture toughness KIC and improve fracture resistance. Mechanical strengthening can repair the original micro‑defects on the alloy tooth surface, optimize the stress field distribution in the surface layer, passivate crack tips, effectively inhibit crack propagation, and significantly increase the fracture toughness KIC of the alloy teeth.

II. Comparative Testing

1. Operating conditions: A large domestic tungsten–molybdenum mine, where the ore is dense and extremely hard, with a rock hardness coefficient f = 14–16. The strata exhibit excellent integrity and high abrasiveness, making this a typical operating scenario characterized by the most severe drill‑bit wear.

2. Test Results:

(1) Post-processing of alloys

(2) Ordinary alloy

Results: The overall drill bit life was improved by 10%, with stable performance, high penetration rates, and a 20% reduction in tooth breakage.

III. Conclusion

The post‑processing technique for alloy components, by means of surface‑level mechanical strengthening and modification, can effectively optimize the physical properties and stress state of the alloy teeth on downhole drill bits, fundamentally enhancing their wear resistance and impact toughness, thereby addressing the core failure issue of rapid tooth wear and easy fracture in high‑hardness rock formations.