热处理对石油管材用Ti-6Al-4V-0.5Ni-0.05Ru钛合金组织和性能的影响

The new Ti-6A1-4V-0.5Ni-0.05Ru titanium alloy was designed for oil country tubular goods (OCTG) in the rigorous oil & gas exploration environment of China. However, the hot working technology and heat treatment of this new titanium alloy are unclear. The effect of hot rolling process and heat treatment on microstructure and tensile properties of Ti-6AI-4V-0.5Ni-0.05Ru titanium alloy were investigated by optical microscopy, mechanical performance test, electron backscatter diffraction (EBSD) analysis and transmission electron microscope (TEM) observation. The results show that the hot rolled plate has good deformation ability after 80% deformation rolled in alpha+beta two-phase zone (940 degrees C) and beta phase zone (1000 degrees C), and no macroscopic cracks are observed. After hot rolling in alpha+beta phase zone, the single annealing treatment homogenizes the microstructure to a certain extent, but the grain size is still large, and the longitudinal and transverse microstructure of the rolled plate is still quite different. After hot rolling in the beta phase zone, the microstructure is smaller and more uniform than that rolled in alpha+beta two-phase zone (940 degrees C), and the morphology of the longitudinal and transverse microstructure is basically the same. Under different hot rolling temperatures, the smaller and more uniform microstructure will be obtained using double annealing treatment. With the increase of single annealing temperature, the tensile strength of hot rotted plate decreases, and the impact energy and impale toughness increases. When using double annealing treatment, the strength can be improved but the toughness of the plate is reduced. In the same heat treatment process, a good match of strength and toughness can be obtained by increasing the hot rolling temperature to 1000 degrees C and single annealing at 850 degrees C.