| 摘要 |
A steel tooth rolling cutter earth boring drill bit comprises a bit body (12) with a threaded upper end (24) for attachment to the end of a drill string, and a lower end comprising three legs (14, 16) extending downwardly from the bit body and with a rolling cutter (18, 20, 22) rotatably mounted on each leg. A layer of wear resistant material is applied to a portion of each rolling cutter and comprises wear resistant particles in a substantially steel matrix (38). The steel matrix (38) is integrally formed with the cutter in a rapid, solid state densification powder metallurgy (RSSDPM) process, and comprises a duplex microstructure comprising from about 10 to 40 volume percent austenite (42) and from about 60 to 90 volume percent martensite (40). The duplex microstructure may be achieved by incorporating a minor fraction of pure nickel and/or manganese powder in the powder mix used in the process, thereby providing nickel or manganese enrichment of the austenitic zones of the matrix. <IMAGE> |
