Research And Application On The Technology Of Frictional Welding And Heat Treatment Of Drill Pipes

This paper focus on the study of frictional welding and heat treatment technology for drill pipes.In order to meet the requirements of the standard,such as mechanical properties,hardness and metallurgical structure of drill pipes' weld bead,we begin with the study of preparation for pipe body and joint,frictional welding parameter design,heat treatment process planning,which are all affecting weld bead's quality.By means of theoretical design,experimental demonstrate and field inspection,process programs are optimized constantly,until the fictional welding drill pipes are up to standard.Research shows that the energy required for welding have to do with drill pipe thickness and welding area,greater thickness need much more energy.When the moment of inertia by theoretical calculating is between 2 different grades,it is better to choose the higher grade.For smaller thickness,if use the higher grade,we'd better reduce the rotating speed to get the reasonable shortening.Heat treating after frictional welding is an effective method for improving impact toughness.Annealing process also has an effect on impact toughness,and meanwhile,helps to get rid of fins.The main cause leading to bend fracture is imperfect decomposition of quenched martensite.It can promote quenched martensite to decompose completely by increasing drawing temperature and extending holding time,so as to reduce strength and improve plasticity.Frictional welding drill pipes can meet the requirements of property index,different blocks,depth,well types of field drilling.The research and application of this technology has produced positive social and economic benefits,having broad prospects.