 Drill Collar Drill Collars are manufactured from AISI 4145H or 36CrNiMo4 modified steel, and are supplied in the "as rolled" surface finish condition. Alternative surface finishes can be provided.  Material: AISI 4145H or AISI 4145H Modified Type: slick and spiral Length:10’~32’ OD size range: 3-1/8"~12" Connection Thread: IF FH REG Trepanning and Heat treatment: Drill collars are trepanned and drifted to API Spec 7. Full-length heat-treatment processes ensure that mechanical properties meet or exceed API Spec 7 requirements. A hardness range of 285-341, Brinell Hardness and Charpy gV h notch minimum impact strength of 40 ft-lb at 70OF are guaranteed one inch below the surface.  |