Optimization of preheating mode when restoring interlocks of drill pipe by welding

The article is devoted to the optimization of technology of drill pipe repair by welding in respect of selection mode preheating. Thepaper analyzes modern sources of information on the selection mode preheating. The microstructural state of the metal body of the castle drill after the restoration was studied;the ways of further improving the technology were planned.
Materials and methods
Research subject of drill pipe tool joints after recovery, its chemical composition. Industrial standards were used to analysis.Also were used an optical microscope «Leitz» MM6, microprobe analyzer «Jeol» Superprobe 733, and atomic emission spectrometry with inductively coupled plasma PMI Master.
Results
Welding technology should be conducted to ensure the minimum depth of welding of the base metal. It could be accomplished if the thickness of welding metal was decreased to point that providesa proper repair and the risk free quality of such repair. Identification of the optimum thickness of a weldmetal is the goal of the further study.
Сonclusions
The surfacing samples study revealed the positive impact of preheating metal parts of the castle before applying surfacing. According to the combination ofthe studied characteristics as the best mode should be recognized the preheating in the inductorat a temperature of 250°C and calcination of flux at 350°C.