Aging Treatment Effect on Microstructure and Mechanical Properties of Ti-5Al-3V-1.5Mo-2Zr Titanium Alloy Drill Pipe
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JMEPEG https://doi.org/10.1007/s11665-020-05191-0
Aging Treatment Effect on Microstructure and Mechanical Properties of Ti-5Al-3V-1.5Mo-2Zr Titanium Alloy Drill Pipe Chun Feng, Ruizhe Li, Yonggang Liu, Le Liu, Wenwen Song, and Fangfang Zhang (Submitted February 20, 2020; in revised form September 9, 2020; Accepted September 20, 2020) Titanium alloy drill pipe material used in the oil and gas industry has excellent characteristics such as highspecific strength, high-temperature resistance, and corrosion resistance. In this study, a systematic examination of the aging process of Ti-5Al-3V-1.5Mo-2Zr drill pipe material, and the microstructure evolution and properties was carried out. The results show that the optimum solution system is 930 °C/1 h/WQ (water quenching). After the aging treatment, the granular changes for a and b phases lead to an increase in the size of the initial lamellar a phase, the volume fraction of the secondary a phase, and the overall strength while the elongation decreases. As the aging temperature increases, the tensile strength and yield strength initially increase by 27 and 29.5%, respectively, and subsequently decrease. The elongation decreases to 9.5%, leading to an excellent performance. With the gradual decrease in the tensile strength and yield strength, the elongation increases gradually. When the heat treatment process is 930 °C/1 h/WQ + 600 °C/6 h/AC, the elongation is 11.5%. TEM observations revealed that a large number of dislocation piles existed at the a/b phase interface after aging treatment, thereby, increasing alloy strength. The more the volume fraction of the secondary a phase precipitated, the smaller the size, leading to a more significant strengthening effect. Keywords
aging Treatment, mechanical microstructure, titanium drill pipe
Properties,
1. Introduction Titanium alloys have high-specific strength, high-temperature resistance, corrosion resistance, and other excellent characteristics. They are not only widely used in aerospace applications, but also for complex conditions such as ultra-deep wells, extended wells, sulfur-containing wells, short radius wells, high temperature, and high-pressure wells in oil and gas well drilling (Ref 1-4). The TA15 alloy is a type of near-a titanium alloy. The Russian equivalent grade is called the BT20. It is solid solution strengthened by the a-stabilizing element Al, and the neutral elements Zr and b-stabilizing elements Mo and V are added to improve the plasticity of the alloy. In order to address the harsh drilling environment (high temperature, high pressure, and high corrosion) and the other problems encountered in the development of the petroleum industry in recent years, Feng Chun and others have actively developed titanium alloy petroleum pipes. Based on the TA15 Chun Feng and Yonggang Liu, State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, CNPC Tubular Goods Research Institute, XiÕan 710077, China; and Ruizhe Li, Le Liu, Wenwen Song, and Fangfang Zhang, State Key
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