The key process of TZM sheet from powder metallurgy to precision rolling
TZM sheet (titanium zirconium molybdenum alloy sheet) is a high performance high temperature material based on molybdenum, with its excellent high temperature strength, creep resistance and corrosion resistance, is widely used in aerospace, nuclear energy and high temperature industrial fields.
1. Raw material preparation: high purity molybdenum base alloy powder
The production of TZM plate begins with the refinement of high purity raw materials: alloy ratio: molybdenum (Mo, ≥99.2%), titanium (Ti, 0.4%~0.55%), zirconium (Zr, 0.06%~0.12%) and trace carbon (C, 0.01%~0.04%). Powder mixing: molybdenum powder, titanium hydride (TiH₂), zirconium hydride (ZrH₂) and graphite powder are evenly mixed by a ball mill to ensure the uniformity of composition (deviation ≤0.5%). Key control point: powder size should be controlled in 3~10μm, too fine easy oxidation, too coarse will affect the sintering density.
2. Powder metallurgy molding: sintering and densification
TZM alloy billets are prepared by powder metallurgy process: cold isostatic pressing: the powder is pressed into billets under 200~300MPa pressure, and the density reaches 80%~85% of the theoretical value. High temperature sintering: Two-stage sintering in a hydrogen or vacuum environment: Pre-sintering (1200°C, 2 hours) : removal of adsorbed gases and residual stress. Final sintering (2000~2200°C, 4~6 hours) : to achieve diffusion bonding between particles, density increased to ≥98%. Core equipment: cold isostatic press, high temperature molybdenum wire sintering furnace. Technical difficulties: It is necessary to strictly control the sintering temperature and atmosphere to avoid oxidation of titanium and zirconium elements.
3. Hot processing: forging and hot rolling
TZM alloy is brittle at room temperature, and needs to be opened by high temperature plastic processing: forging: the sintered billet is heated to 1350~1450°C (above the recrystallization temperature of molybdenum), and repeatedly forged on the forging press to refine the grains and eliminate the internal pores.
Hot rolling: Under the protection of argon, the billet is rolled into a plate with a thickness of 5~10mm by multi-pass hot rolling process, and the rolling temperature should be maintained at 1200~1300°C. Key parameters: deformation of each pass ≤20%, prevent edge cracking; After rolling, rapid cooling is needed to inhibit grain growth.
4. Cold rolling and annealing: precision sheet forming
Cold rolling combined with annealing process to achieve precision thinning of TZM plate: multi-pass cold rolling: at room temperature through the four-roll mill step by step rolling, the target thickness can reach 0.1~1.0mm, each pass deformation control of 8%~15%. Vacuum annealing treatment: After 3 to 4 passes of rolling, it is necessary to eliminate work hardening in the vacuum annealing furnace (1100 to 1250°C, heat preservation for 1 to 2 hours) and restore the plasticity of the material. Performance improvement: After annealing, the tensile strength of TZM sheet can reach 800~1000MPa, and the elongation is ≥15%. Core equipment: precision four-high rolling mill, vacuum annealing furnace (limit vacuum ≤1×10⁻³Pa).
5. Surface treatment: antioxidant and functional coating
TZM sheet is easy to oxidize at high temperature, and it needs to be improved by surface treatment to improve stability: chemical polishing: The surface oxidation layer is removed by nitric acid-hydrofluoric acid mixture (volume ratio 3:1), and the roughness Ra is less than 0.2μm. Ion coating: Titanium nitride (TiN) or alumina (Al₂O₃) coating is deposited on the surface, suitable for the application of TZM sheets in aerospace thermal protection layers. Silicification: The MoSi₂ protective layer is generated by the siliconizing process, which significantly increases the oxidation resistance temperature (from 600°C to 1600°C). Quality control: Coating thickness (1~5μm) and bonding strength (≥50MPa) need to be strictly tested.
6. Cutting and packing
Precision machining and protection of TZM tablets according to terminal requirements:
Laser cutting: The use of fiber laser (wavelength 1070nm) cutting, to ensure that the edge without burrs, suitable for nuclear grade TZM sheet preparation process. Vacuum package: Put the finished TZM sheet into an aluminum-plastic composite bag, and fill it with argon after vacuuming to avoid oxidation in transportation and storage.
The production process of TZM tablets incorporates cutting-edge technologies such as powder metallurgy, high-temperature plastic machining and surface engineering, and the stability of its performance directly determines its reliability in extreme environments. With the rapid development of aerospace, nuclear energy and high-end equipment manufacturing, high-precision TZM sheet processing technology and TZM sheet functional coating technology will become the key direction of industry breakthroughs.
Mosten Alloy can produce TZM sheet, TZM block, TZM foil, TZM rod, TZM wire, TZM processing workpiece according to customer demand.
