Non-magnetic drill collars are made of a low-carbon, high-chromium-manganese alloy steel. They are refined through a strict chemical composition ratio and forged to achieve their mechanical properties, resulting in excellent low magnetic permeability, high strength, excellent intergranular corrosion cracking resistance, and superior wear resistance. When the magnetic field strength is 1×10⁵/4π A/m, the relative magnetic permeability μr of the non-magnetic drill collar ≤ 1.010.
The magnetic flux density gradient along the inner hole of the non-magnetic drill collar at any distance of 100 mm is ≤ 0.05 μT.
