Analysis of Magnetic Particle Indication on Welding Line of Drill Pipe

The magnetic particle induction occurred on the welding line of drill pipe is a typical quality problem during the drill pipe production. The characteristics of and influence factors on the magnetic particle indication on the welding line of drill pip are analyzed,metallographic observation is conducted and energy spectrum identification by scanning electron microscope is made. After above jobs it is found there are two kinds of magnetic particle indications on the welding line of drill pipe which are strip type and dot type,all adjacent and parallel to the welding line,appearing in a ring type belt area of pipe ends which is 5 mm away from the welding line. Analysis shows the magnetic particle induction occurred on the welding line of drill pipe is caused by the inclusions contained in drill pipe material therefore it is suggested a inspection standard for the magnetic particle induction on the welding line of drill pipe should be set up for judging which is accepted and which is rejected.