The Vibratory Stress Relief of Drill Pipe

Abstract

Drill pipe is made from 35CrMnMo. The used drill pipes were curved, when they were aligned and deformed, there is high macro residual stress in the aligned used drill pipe. In active service, the macro residual stress releases and thus causes considerable deformation of the aligned used drill pipe. The vibratory stress relief is introduced to the aligned used drill pipe. The vibratory stress relief of the aligned used drill pipe was carried out. The mechanical properties of the aligned used drill pipe were measured before and after vibration. Seven points vibratory stresses were measured. The macro residual stress was measured before and after vibration. The macro residual stress decreased notably. The mechanical properties changed slightly. The vibratory wave is standing wave. The vibratory stress relief is valid for macro residual stress relieving of the aligned used drill pipe. The aligned used drill pipes were steady in latter active service. The mechanism of the macro residual stress relieving by vibration on the aligned used drill pipe is discussed. The “double-dynamic mechanism” is introduced to explain the course of macro residual stress relieving in the test.