T/CSBM 0007-2021 Active

Main Technical Content: **Technical Requirements:** **Chemical Composition:** (1) The Ti-24Nb-4Zr-8Sn alloy, designated as Ti2448, shall comply with the chemical composition specified in Table 1. (2) The allowable deviation of the chemical composition of the product during the buyer's reinspection shall comply with the provisions of GB/T 3620.2. **Alloy Melting:** (1) The ingots used for producing Ti2448 alloy processing materials shall be melted in a vacuum self-consuming arc furnace, with a minimum of three melting cycles. (2) The use of tungsten electrodes for GTA welding is prohibited. (3) Any recycled materials of titanium and titanium alloys are not permitted as raw materials for producing ingots and processing materials. **Heat Treatment:** (1) The recommended heat treatment process for solution annealing is: 650°C to 750°C, holding time 0.5h to 1h, air cooling. (2) The recommended heat treatment process for aging annealing is: 450°C to 550°C, holding time 0.5h to 4h, air cooling. (3) The supplier may adjust the heat treatment process as needed. **Mechanical Properties:** (1) The room-temperature mechanical properties of rods shall comply with the specifications in Table 2. (2) The room-temperature mechanical properties of wires shall comply with the specifications in Table 3. (3) The room-temperature mechanical properties of plates shall comply with the specifications in Table 4. (4) The room-temperature mechanical properties of other specifications products shall be reported as measured data. **Microstructure:** (1) The cross-sectional microstructure shall not contain cracks, pores, metallic or non-metallic inclusions, or other visually observable metallurgical defects. (2) The microstructure shall be a single-phase β phase or a two-phase β phase with fine α phase precipitates. The α phase shall have a fine lamellar structure that may not be resolved by optical microscopy, but is essential for obtaining adequate stren