Development of a hardbanding material for drill pipes based on high-manganese steel reinforced with complex carbides

based on high-manganese steel reinforced with complex carbide
particles was developed by combining thermodynamic modelling
within the CALPHAD approach and first-principles calculations. The
alloy, deposited by flux cored arc welding on a steel substrate, has a
composite structure consisting of manganese-austenite with the
ability to work hardening, fine (up to 5 µm) inclusions of the multicomponent carbide (Nb, Ti, Mo, V) and C the thin layers of (Mo,V)C
at the austenite grain boundaries. The comparative wear tests carried
out with commercially available hardfacing materials of the Fe-W-C
and Fe-Cr-C systems showed that the proposed alloy has the best
combination of properties preventing the wear of the drill casing,
while its abrasion resistance, as well as wear resistance in sliding
friction conditions by steel counter body, is close to hypereutectic
high chromium alloys. The microhardness tests performed on
deformed specimen areas after the friction tests show the presence of
a significant hardness gradient in the range of 800-450 HV at a
distance of about 300 µm when moving perpendicularly away from
the zone of friction contact. During the microscopic observation of
the layer deposited with the developed alloy and the interfaces
between the deposit and the base steel, no cracks or pores
delamination were detected, indicating a strong metallurgical
bonding. The hardbanding process was performed for drill pipe joints
with the worn Fe-based high chromium alloy hardbanding after
exploitation, which allows the drill pipe to be re-used with the same
durability.