Water Mist Heat Treatment Equipment Manufacturing And Process Research On The Friction Welding Joint Of Oil Drill Pipe

Oil drill pipe is one of the important tools in the process of oil exploration. Using themethod of welding drill pipe and joint could realize reuse of drill pipe. The usability of theoil drill pipe is controlled by heat treatment of the weld zone, while it is substandard ofmechanical performance adopting the conventional air-cooled tempering heat treatmentprocessing which caused insufficient cooling speed of the small size of oil drill pipe. Inthe presence paper, a type of oil drill pipe friction weld heat treatment equipment usingwater as cooling medium was fabricated. The microstructure and mechanical properties ofthe friction welding joint under different heat treatment parameters (water and air pressure)were analyzed using the new equipment to obtain the expected optimal process parameters.The operating system of the water mist heat treatment equipment is designed to controlthe displacement and the precisely motion by PLC+PID dual-loop control and using PID tocontrol the atomization effect. The system cooperated with the timer to ensure processstability and cooling time accurate. It also has the functions of automatic, manual control,self-tuning and fault warning to achieve the full automatic at the beginning of heating.The experimental results of the water mist heat treatment show that the microstructureof3.5inches (Φ88.9mm) and2.7inches (Φ73mm) oil drill pipe welding joint producedby the water mist cooling method of920℃+1min water spray quenching heat and660℃+6min tempering, are with uniform fine tempered sorbite and a little residual austenite.Mechanical performance is:3.5inches-the yield strength of900MPa, tensile strength of930MPa and impact energies of93J;2.7inches-the yield strength of750MPa, tensilestrength of840MPa and impact energies of160J.