Molybdenum and TZM Alloy Plastic Processing Technology

To rational design the plastic processing technology can effectively change the state structure of molybdenum and TZM alloy to improve its performance, especially improved brittleness. In molybdenum and TZM alloy plastic processing, deformation temperature, deformation degree and heat treatment temperature are important parameters affecting its structural state. During plastic processing there is must go through three temperature stages, which are hot working, warm working and cold working.

There are two ways of thermal working. One is processing above recrystallization temperature with large rolling reduction for cogging, and through hot forging, rolling and extrusion can obtain dense structure equiaxed coarse-grained organization, having low dislocation density and internal stress. The second is processing at proximity to or on the recrystallization temperature, through controlling dynamic recrystallization plastic deformation, so the deformation and recovery, recrystallization can reach dynamic equilibrium, so as to obtain significant fine grain structure or sub-grain organization and fine equiaxed grains under high temperatures recovered state. In the hot deformation process, strengthening and softening to achieve a balance, the temperature and deformation degree can control grain size, so in thermal processing is impossible to form the dislocation cellular tissue.

Warm working is processing at a temperature above the plastic - brittle transition temperature, but below the recrystallization temperature. Warm working, it is an important processing step, generally intermediate processing step, but also can be finished product procedure. Through warm processing can obtain sub-structure, so that molybdenum and TZM alloy having high strength and toughness.

Cold working is unlike general room temperature processing, which is processing above plastic - brittle transition temperature, but below t * characteristic temperature. Cold working at t * temperature the crystal lattice Peine strength and yield strength have been significantly improved and the dislocation density have been increased. With the increase of deformation, dislocation chaotically distributed on dislocation forest way, or formed dislocation tangles deformed cells. In the cold working process should follow with stress annealing, so that the process can smoothly.

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