Study on cold rolling and annealing co-forming process of TZM alloy sheet
In aerospace, nuclear energy, semiconductor and other high-end fields, the precision forming of high melting point molybdenum base alloy sheet is very high. However, TZM alloy (Mo-0.5Ti-0.1Zr-0.02C), as a typical refractory material, exhibits remarkable work hardening characteristics during cold rolling, and the traditional process is difficult to achieve efficient production of TZM sheet. The cooperative processing system of multi-pass cold rolling and vacuum annealing can solve this problem. Industrial production of 0.1-1.0mm ultra-thin TZM alloy sheet, and greatly improve its comprehensive mechanical properties.
TZM alloy exhibits remarkable work hardening properties during cold rolling. By designing the deformation of 8%-15% per pass, the growth rate of dislocation density is effectively controlled, and the premature formation of micro-cracks is avoided. The special roll system configuration of the four-roll mill (work roll diameter Φ80-120mm) is used to achieve high precision shape control, and the thickness tolerance can be stabilized at ±0.005mm.
TZM sheet vacuum annealing process (1100-1250℃/1-2h) through three stages to achieve material repair: recovery stage (800-1000℃) dislocation rearrangement to form a subcrystalline structure; In the recrystallization stage (1000-1200℃), the new equiaxed grains nucleate and grow. Grain coarsening stage (>1200℃) by controlling secondary recrystallization to inhibit grain overgrowth. The vacuum environment (≤1×10-3Pa) effectively inhibited the high-temperature oxidation, and the surface oxygen increment was controlled below 0.05mg/cm2.
TZM sheet annealing system matching: the step heating strategy is adopted: 300-800℃ heating rate is 5℃/min, which is used to eliminate rolling stress; 800-1200℃ heating rate of 8℃/min, promote recrystallization; The temperature fluctuation in the insulation stage is controlled at ≤±5℃ to ensure the uniformity of the organization.
After three passes of rolling and annealing, the grain size of TZM sheet is refined from the initial 50μm to 8-12μm, and the dislocation density is reduced by two orders of magnitude (from 1015m-2 to 1013m2). Transmission electron microscopy (TEM) analysis showed that the uniform distribution of TiC and ZrC strengthened phases (size 20-50nm) was extracted after annealing, and the strength and plasticity were improved cooperatively.
Mosten Alloy can produce TZM sheet, TZM block, TZM foil, TZM rod, TZM wire, TZM processing workpiece according to customer demand.
