The cleaned batch tantalum tubes are placed into the heat-resistant sleeve tube, and then the heat-resistant sleeve equipped with tantalum tubes is sent into the vacuum annealing furnace along the axial direction through the automatic transmission device. The automatic transmission device stops working. The vacuum annealing furnace is a true air induction annealing furnace, and the vacuum induction annealing furnace is provided with a heating section and a cooling section.
Annealing in vacuum induction annealing furnace: Start the automatic transmission device to send tantalum tube at the speed of 10-50cm/min and heat it through the heating section of induction coil of vacuum induction annealing furnace. The heating section is required to heat up to the recrystallization temperature of tantalum tube within 3-5 seconds: The heating temperature is 1300-1600°C. The heat-resistant tube equipped with tantalum tube passes through the heating section of the induction coil continuously, and the axial temperature of the whole tube presents a step distribution. Under this temperature distribution, the pipe crystal texture rules are distributed along the axial direction, and the new crystal nuclei without distortion formed in the recovery process are not easy to aggregate and recrystallize, resulting in grain growth.
Rapid cooling in vacuum induction annealing furnace: the heat-resistant sleeve equipped with tantalum tube from the heating section of the furnace is evenly sent to the cooling water jacket in the cooling section of the furnace for rapid cooling. The tantalum tube is cooled to 300-60(TC) within lmin-2min, at which time the vacuum induction annealing furnace stops heating. Then with the furnace naturally cooled to room temperature.
It has the following advantages: 1 Good organization and performance of the product: due to rapid local heating, rapid cooling. In the process of recrystallization, the grain size is fine and uniform, the grain size is more than three grades better than the traditional vacuum annealing pipe, and the mechanical properties are obviously better than the traditional vacuum annealing furnace. The tensile strength, yield strength and elongation of annealed tantalum tube are 280MPa, 231MPa and 26.4%. At the same time, the temperature is distributed in step along the axial direction, which has the advantage of step heating and annealing. The pipe texture is distributed regularly along the axial direction. The skin effect of induction heating makes the tantalum tube wall temperature rise rapidly, and the tantalum tube wall dissipates heat the fastest, which makes the tantalum tube wall grain size smaller and improves the surface performance. The high vacuum environment of the invention ensures that tantalum is not polluted by oxygen, nitrogen, hydrogen, carbon and other gases in the air or in the heating atmosphere during annealing. The oil on the surface of the pipe and the processing lubricant flapped sharply in the vacuum environment, which also avoided the reaction with the pipe and damaged the performance of the pipe.
