Heat Treatment Technology of the Dissimilar Materials' Friction Welded Joints of the Geological Drill Pipe

In this paper, the drill pipe and its tie-in are welded by friction welding successfully. It's the first time to introduce friction welding technology into the geological drill pipe's production. The influence of different post weld heat treatment conditions on the microstructures and mechanical properties of friction welded joints between drill pipe DZ60 steel and its tie-in 40Cr steel has been discussed.Meanwhile, the microstructures and mechanical properties of friction welded drill pipes have been compared with those of hotupsetting drill pipes. As a result, the conventional mechanical properties of drill pipes' friction welded joints have exceeded the values of geological drill pipe (DZ60)that specified by the technical criterions of Geological and Mining Department, and also are greater than that of the hot-upsetting geological drill pipes.Moreover, the results showed that the tensile strength and yield strength of friction welded joints can be improved efficiently if the appropriate tempering condition was adopted. Besides, the mechanical property values will be equal to or exceed the technical standard values of geological drill pipe (DZ60). The technology presented in this paper has been applied in practical geological drill pipe's Production, which can simplify the post weld heat treatment condition and also reduce the production costs.