Unlike beryllium copper (C17200), C72900 is beryllium-free , making it safer to handle in manufacturing (no toxic beryllium dust) while achieving comparable or superior performance in certain applications.
Not recommended for strong oxidizing acids (e.g., nitric) or ammonia-rich environments. uns c72900 c729
| Stage | Process | Temperature (°C) | Time | Resulting Microstructure | Typical Mechanical Properties | |-------|---------|-------------------|------|--------------------------|--------------------------------| | | 1050 °C → water quench | 1050 °C (1920 °F) | 30 min (per 25 mm thickness) | Fully austenitic, supersaturated in Cu | Soft, highly formable (≈ 70 HRB) | | Aging – H900 | 480 °C (900 °F) | 1 h (air cool) | Fine Cu‑rich precipitates (α‑Cu) + retained martensite | Tensile ≈ 1380 MPa; Yield ≈ 1240 MPa; 44‑48 HRC | | Aging – H1025 | 560 °C (1025 °F) | 1 h (air cool) | Coarser precipitates, slight over‑aging | Tensile ≈ 1150 MPa; Yield ≈ 1060 MPa | | Aging – H1075 | 580 °C (1075 °F) | 1 h (air cool) | Over‑aged, more ductile | Tensile ≈ 950 MPa; Yield ≈ 800 MPa; 30‑35 % elongation | | Direct Age Hardening (DAH) | 480 °C (900 °F) after cold work | 1 h | Similar to H900 but with higher residual stress tolerance | Slightly higher strength than H900 with better toughness | | Stress‑Relief | 370 °C (700 °F) | 1 h | Reduces residual stress, maintains most of the precipitates | Minimal change in strength | Unlike beryllium copper (C17200), C72900 is beryllium-free ,
| Process | Rating/Notes | |---------|--------------| | | Moderate (60% of free-cutting brass C36000). Use carbide tooling. | | Forming | Limited; cold formability decreases with strength. AT temper more formable than XT. | | Welding | Poor – not recommended. Use mechanical fastening or brazing. | | Heat Treatment | Solution treat at 1450–1550°F (788–843°C), water quench, then age at 660–750°F (350–400°C) for 2–6 hours. | Use carbide tooling
| Process | Guidelines | |---------|------------| | | Best performed in the annealed condition. Cold working beyond 20 % strain may cause cracking in the hardened states. | | Welding | Pre‑heat not required for thickness ≤ 12 mm. Recommended filler metals: ER308L , ER309L , ER316L for corrosion‑critical zones, or EPRI‑17‑4 filler for matching alloy. Post‑weld heat treat (solution anneal + aging) restores strength. | | Machining | Good machinability in annealed state; H900 is tougher and may require carbide tooling, low feed, high rpm, and ample coolant. Typical cutting speeds: 60–90 m/min (HSS) → 150–200 m/min (carbide). | | Heat‑treatment after machining | If final dimensions are critical, perform solution anneal → water quench → age after machining to avoid distortion. | | Surface finish | Polished to < 0.2 µm Ra for critical corrosion zones; standard 120‑grit (Ra ≈ 2 µm) is adequate for most mechanical parts. |