CORROSION PROTECTION FOR HEAD SECTION OF EARTH BORING BIT.

摘要

An earth boring bit has a steel body having at least one leg with a depending bearing pin. A cone having cutting elements is rotatably mounted to the bearing pin. A ball plug weld is on the outer surface of the leg. A layer of hardfacing applied to part of the outer surface of the leg, the hardfacing having carbide particles in a matrix. A corrosion resistant coating containing at least 50% nickel is formed on parts of the outer surface of the leg that are free of the layer of hardfacing both above and below the ball plug weld.