Specifications drill collar used for OIL/GAS drilling

Spiral Drill Collars 3 1/8"? 1.sizes: 3-1/8 to 11 inches?
2.Material:AISI 4145H?
3.API Spec 7?

Full-length heat-treatment processes ensure that mechanical properties meet or exceed API Spec 7 requirements. Drill collar material and process traceability are maintained from receipt of mills’ certified raw material to completion of all the manufacturing. Serial numbers are die stamped on bar bodies. Drill collar thread roots, as well as elevator recess upper radius, are cold-rolled. Cold rolling creates a compressive recess upper radius stress condition that increases fatigue life by minimizing crack initiation. All tool joint connections are phosphate-coated or copper plated to improve resistance to corrosion. Optional slip and elevator recesses to improve handling efficiency and safety are also available.? ? ? ? ? ? ? ? ? ? ?