Drill collar

Size Range 3-1/8”——11” Brief Introduction Hengshan drill collars are made of AISI 4145 H or 4145 H modified alloy steel. The chemical composition is controlled strictly during the refining and forging process. It can be divided into the following three types according to the appearance and material: Type A(Cylindrical) Be Made of alloy steel and the cross sections of the inside and outside pipe are both round. Type B(Spiral) Be Made of alloy steel and the outside pipe has spiral grooves. Type C(Non-magnetic) Be Made of stainless alloy steel with rather low Magnetic permeability and the cross sections of the inside and outside pipe are both round. Mechanical Properties A type and B type drill collarODYield Strength MPaTensile StrengthMPaElongation%Brinell HardnessHBImpact APVJmmin79.4 171.431/8 63/4≥758≥965≥13285 341≥54177.8 279.47 11≥689≥930≥13285 341≥54C type drill collarODYield Strength MPaTensile StrengthMPaElongation%Brinell HardnessHBImpact APVJmmin79.4 171.431/8 63/4≥758≥827≥18 177.8 279.47 11≥689≥758≥20 Usage As an important part of drill stem, drill collar can supply the drilling pressure for the drill bit and increase the rigidity of drill stem.