| 摘要 |
Disclosed are methods of hardfacing and hardfaced tool joints used for connecting together drilling pipe for drilling bore holes in the earth, such as drilling to possible oil and gas formations. The hardfacing is welded to the outer surface of the box member of the tool joint and forms a surface harder than silicious earth particles but a surface which does not cut casing through which the drilling pipe and tool joints move. Hardfacing alloys having the foregoing properties contain primary carbides in a matrix which are present in an amount to form a plurality of cracks of not less than one in 3 inches on cooling from molten to solid state are satisfactory. Such cracking causes no damage to the box member, provides an indication of the primary carbides present and hence the abrasion resistance of the hardfacing and provides a long wearing service life for the box member.
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