Rapid vacuum annealing method for tantalum tube. It consists of the following steps: the tantalum tube is cleaned and dried. The cleaned tantalum tube is placed into the heat-resistant tube and sent into the vacuum induction annealing furnace along the axial direction. A three-stage vacuum system is used to pump it to a vacuum of 10-2Pa. Ensure its internal high vacuum state. Tantalum tube is annealed in vacuum induction annealing furnace, that is, heating and rapid cooling are completed in the furnace. This method is used for annealing, the tantalum tube heating up quickly, the tantalum tube product structure and performance is good, the tantalum tube quality consistency is good, low energy consumption, low operating cost, annealing equipment investment is small, simple disassembly and maintenance. No long time heat preservation, low power consumption. After annealing, the allowable stress of tantalum tube increases by about 60% compared with that of traditional vacuum annealing furnace, and the tantalum material can be saved by about 40% under the same service strength, and the economic benefit is remarkable.
Work hardening occurs in cold processing such as rolling or drawing, and annealing is generally required at 1000-120(TC) high temperature before further processing to eliminate the internal stress and restore the processing plasticity of the tantalum pipe, which is convenient for further processing such as diameter reduction and wall reduction to reach the desired size. Most of the finished pipe is soft or semi-hard state, need full annealing before use for recrystallization or incomplete annealing to eliminate internal stress. Because tantalum has strong chemical activity at high temperature, it will interact with oxygen, nitrogen, hydrogen and other gas components in the air or heating atmosphere, as well as with processing lubricants and oil on the surface of the pipe, so as to make the surface of the tantalum pipe inhale or oxidize, and damage the performance of the tantalum tube. According to the relevant literature, for a long time, all the annealing of tantalum tubes at home and abroad are performed by the traditional vacuum annealing furnace. In the traditional vacuum annealing of tantalum tube, resistance heating is adopted, and the heat transfer mode is radiation heat transfer, and the temperature rises slowly. The deformation energy stored in the tantalum lattice is gradually consumed, and the nucleation capacity of recrystallization is weakened. The grains after annealing are coarse and slow in cooling, so that the grains gradually grow up in the cooling process. The strength and plasticity of the product are relatively low.
Because of the high melting point of tantalum, the recrystallization annealing temperature is correspondingly high. The traditional vacuum annealing furnace is limited by materials and has a low temperature limit. For the recrystallization annealing of high melting point tantalum, even if the holding time is excessively prolonged, it is difficult to achieve the purpose of recrystallization annealing. After vacuum annealing, the tensile strength, yield strength and elongation of tantalum tube are 210MPa, 140MPa and 25% respectively.
