Resistance to abrasive wear and metallurgical property assessment of nine casing-friendly hard-banding alloy chemistries: Abrasion resistance assessment using ASTM G65 methodology (standard test method for measuring abrasion with dry sand/rubber wheel apparatus)

Modern drilling areas often involve very abrasive formations in conjunction with aggressive drilling practices including short radius well bore sections, long extended horizontal sections, laterals, HDLS, and tortuous wellbores with high torque and drag. Any one of these conditions individually can contribute to wear and the downgrading of a drill string and down-hole tools, and where they occur in combination they often result in severely accelerated wear. Hardbanding of drill pipe tool joints, BHA and tools has long been accepted and used in the drilling industry to provide a replaceable wear component to reduce the effects of down-hole abrasive wear that can render pipe and tools unfit for service, increase the risk of failure, and significantly raise drilling costs. One primary issue for the end-users of these hardfacing alloys then is how well each alloy type protects the drill string and down-hole components from abrasive drilling conditions, extends the life of the pipe and tools, and reduces the number of times a hardfacing material needs to be reapplied during the life of the component. This paper presents the results of metallurgical examinations and abrasion resistance testing using the dry sand/rubber wheel abrasion test (as described in ASTM G-65 - 04 (2010) Standard Test Method for Measuring Abrasion with Dry Sand/Rubber Wheel Apparatus) on nine (9) casing-friendly hardfacing alloys commonly used in oilfield drilling. The total test regime included alloy chemistry, hardness profile, microstructure, and the measured durability / relative life of each hardfacing. The test results show that the best abrasion resistance is provided by hardbanding alloys that have microstructures in which very hard carbide or boride particles are contained within a more ductile matrix. Under sliding abrasion conditions this provides a level of abrasion resistance much greater than that which would be predicted from homogenous steels with comparable bulk hardness (the well-known "particle- reinforced composite effect"). However, in addition to abrasion resistance, other performance properties such as the tendency to cause casing wear and the tendency for relief-check cracking must also be considered. The tendency for cracking can be predicted both from the microstructure and directly observed visually (from test specimens and actual field applications of the materials). Alloys containing continuous networks of primary and/or eutectic carbides or borides tend to be highly susceptible to cracking, while alloys in which the reinforcing carbides are small, isolated particles, fully separated by the more ductile matrix, are much less susceptible. Of the various hardbanding alloy samples examined in this study, a titanium carbide based alloy showed both the highest resistance to abrasive wear and a microstructure indicative of excellent resistance to cracking.