The drill collar is
according to SY/T********7 and API **1 " Specification for Rotary Drill Stem Elements" standard, the material uses AISI
***5H alloy
structural steel to
carry on the deep hole processing, before thread and
spiralgroove
processing against the total cross-section to quenching and the
temperingheat treatment. After thread
examination qualified, and carries on cold
rollingprocessing
to the thread root and the slips, reduces the thread part fatigue
failureto
increase the drill collar service life.
