Performance Test of Weld Zone of Rotary Friction Welding of Titanium Alloy Drill Pipe

Abstract

Abstract With the development of complex oil and gas reservoirs, it is difficult for traditional carbon steel to meet the requirements of drill pipe materials in drilling process. Titanium alloy has gradually become a new choice of drill pipe material because of its low density and good corrosion resistance. Titanium alloy has poor weldability and weld zone of titanium alloy drill string is easy to become initial defect and lead to drill pipe failure. Therefore, it is essential to evaluate the performance of titanium alloy drill pipe weld zone. In this paper, the weld zone of titanium alloy rotary friction welding is tested. Metallographic structure, hardness, tension and impact mechanical tests, fracture toughness evaluation and bending fatigue test are carried out. The test results show that the metallographic structure of weld zone changes under the influence of temperature, resulting in different mechanical properties of weld zone from that of pipe body zone. The yield strength and tensile strength in the weld zone are higher than those in the pipe zone, but the fracture toughness is lower than that in the pipe zone. The fatigue life of specimens in weld zone is more than 107 in drilling mud environment. In general, the mechanical properties of weld zone meet drilling requirements.