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Recrystallization TZM Alloy Hot Deformation Characteristics

Recrystallization state TZM alloy at room temperature is brittle, and therefore difficult to deform, so alloy cold rolling and warm rolling to avoid full recrystallization annealing. Processing at high-temperature, since the material becomes soft, lower intensity, is conducive to machining distortion. Studying the recrystallization state TZM alloy high temperature deformation has great significant for understanding the effect of recrystallization annealing on TZM alloy microstructure and hardness.

The alloys were annealing at 1100,1200,1300,1400, 1500 and 1600 ℃, and heat preservation for 1h, observing at different annealing temperature the organizational structure of the alloy. After 1100 ℃ annealing, alloy grains become processing state fiber organization, but after 1600 ℃ annealing, the grain becomes coarse strip and grains growth, indicating recrystallization completed. Hardness of the alloy with annealing temperature decreased, at 1600 ℃, the material has been significantly softened.

At 1600 ℃ to operate hot compression deformation on alloy. After compression deformation alloy has significant deformation, shorten its length, radius increases, and the intermediate raised to drum. When the strain capacity is less than 5%, the stress rapidly increases with strain increasing and hardening obvious. When the strain capacity is higher than 5%, the increase rate of stress is become slowed, work hardening rate becomes low as well. After compression, alloy microstructure is strip shape and both ends deformation is small. The middle grains shows oval-shaped, intermediate has large deformation. It is indicated that along the axial deformation of the alloy is uneven. Observation alloy radial direction microstructure found, there is not much difference between the center and the edge of the grain size and shape, indicating relatively uniform along the radial deformation. After heat compression there are many microcracks is formed in line with the compression direction on alloy’s grain boundaries. The alloy after recrystallization grains becomes coarse. And when the orientation is not conducive to plastic deformation there will a lot of stress concentration occurs at grain boundary. When the stress concentration reaches a certain degree, it will crack. Therefore, in the processing of proceeding, it should choose appropriate annealing temperature to prevent cracks.

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