Refractory Metal 50Cr-50Ni-Cb-AC (Spheroidize annealed)
Heat-treated state · default condition
UNS R20501 · ASTM A560 Gr 50Cr-50Ni-Cb
Standard supply condition for sand/investment castings — tube supports, hangers, burner parts for fuel-ash corrosion service.
Values for the AC condition
Other 50Cr-50Ni-Cb tempers and conditions
50Cr-50Ni-Cb is listed in 4 conditions; see the grade overview at 50Cr-50Ni-Cb.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
As-cast plus stress relief | Choose when castings are heavily welded or machined and residual stress could cause distortion or cracking on first heat-up. | 370 | 570 | 9 | 205 HB | 1.6 % IACS |
As-welded deposit | Condition of weld repairs and of protective weld overlays applied to cheaper substrates in boiler fuel-ash zones. | 380 | 560 | 5 | 19 HRC | 1.6 % IACS |
ACDefaultThis page Spheroidize annealed | Standard supply condition for sand/investment castings — tube supports, hangers, burner parts for fuel-ash corrosion service. | 390 | 590 | 8 | 16 HRC | 1.6 % IACS |
Hot isostatic pressed | Specify for critical, thermally cycled or pressure-containing castings where shrinkage porosity must be closed to raise ductility and creep life. | 400 | 630 | 12 | 16 HRC | 1.6 % IACS |
What is 50Cr-50Ni-Cb-AC?
50Cr-50Ni-Cb-AC is 50Cr-50Ni-Cb heat treated to AC — standard supply condition for sand/investment castings — tube supports, hangers, burner parts for fuel-ash corrosion service. 50Cr-50Ni-Cb-AC has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 61% of refractory metal grades. Elongation at break is 8% and the elastic modulus is 190 GPa (27.6 Msi). 50Cr-50Ni-Cb-AC has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 54% of refractory metal grades. It melts at 1,370°C (2,498 °F).
Advantages
- Low embodied carbon — 10.5 kg CO₂/kg, better than 88% of refractory metal grades
Limitations
- Hard to polish — 45/100, worse than 98% of refractory metal grades
- Low electrical conductivity — 1.6 % IACS, worse than 96% of refractory metal grades
- Poor heat conductor — 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 90% of refractory metal grades
- Limited formability — 8/100, worse than 90% of refractory metal grades
- Difficult to machine — 12/100, worse than 86% of refractory metal grades
50Cr-50Ni-Cb-AC properties
Typical room-temperature values for 50Cr-50Ni-Cb-AC; 23 are specific to this condition. Other listed values are 50Cr-50Ni-Cb reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
50Cr-50Ni-Cb-AC has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 54% of refractory metal grades. It melts at 1,370°C (2,498 °F).
Mechanical17
50Cr-50Ni-Cb-AC has a yield strength of 390 MPa (56.6 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 61% of refractory metal grades. Elongation at break is 8% and the elastic modulus is 190 GPa (27.6 Msi).
Thermal6
50Cr-50Ni-Cb-AC is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 14 W/m·K (8.09 BTU/hr·ft·°F), worse than 90% of refractory metal grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
50Cr-50Ni-Cb-AC conducts electricity at 1.6 % IACS, worse than 96% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (88/100), better than 64% of refractory metal grades.
Sustainability4
Producing a kilogram of 50Cr-50Ni-Cb-AC takes about 135 MJ of energy and emits 10.5 kg of CO₂ — less than 91% of refractory metal grades. Typical recycled content is 30%.
Manufacturability8
50Cr-50Ni-Cb-AC's machinability is not recommended (12/100, worse than 86% of refractory metal grades); weldability poor (25/100); formability not recommended (8/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 50Cr-50Ni-Cb-AC
Is 50Cr-50Ni-Cb easy to machine?
Very difficult and abrasive — use rigid setups, ceramic or coated-carbide inserts, low speed with heavy positive feed, flood coolant; grinding or EDM for finish features on hard duplex structure.
Can 50Cr-50Ni-Cb be welded?
GTAW/SMAW with matching 50Cr-50Ni-Nb filler only, low heat input, interpass temperature control and minimal restraint; highly sensitive to hot cracking and post-service embrittlement, so field repair of aged parts is generally not recommended.
Can 50Cr-50Ni-Cb be formed, bent or molded?
Not cold formable — parts are produced as sand or investment castings (air or vacuum melt); allow generous fillets and controlled solidification to avoid shrinkage porosity.
What surface finishes work on 50Cr-50Ni-Cb?
Service protection comes from the self-forming Cr₂O₃ scale; shot blast or pickle to remove casting scale, no plating or anodizing needed and paint is pointless at service temperature.
50Cr-50Ni-Cb chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Crduplex Cr-rich α phase former; source of fuel-ash resistance | 48 – 52 | 50 |
| Nbcolumbium (Cb) — carbide/grain-boundary stabilizer, creep strength | 1 – 2 | 1.5 |
| C | ≤ 0.1 | 0.06 |
| Si | ≤ 0.5 | 0.3 |
| Mn | ≤ 0.3 | 0.15 |
| Ti | ≤ 0.5 | 0.2 |
| Al | ≤ 0.25 | 0.1 |
| Fe | ≤ 1 | 0.5 |
| S | ≤ 0.02 | — |
| P | ≤ 0.02 | — |
| Nibalance, nominally ~46–48 % | balance | — |
50Cr-50Ni-Cb-AC — frequently asked
What is 50Cr-50Ni-Cb-AC used for?
50Cr-50Ni-Cb-AC is typically used for furnace muffles and retorts, heat-treat baskets, high-temperature fixturing and carburizing/nitriding equipment. In short: creep-stabilised 50/50 casting; thermal-cycling furnace grade; cast-only, not formable.
What is the yield strength of 50Cr-50Ni-Cb-AC?
50Cr-50Ni-Cb-AC has a typical yield strength of 390 MPa (56.6 ksi) and a tensile strength of 590 MPa (85.6 ksi) — stronger than 61% of refractory metal grades. Strength varies by condition: see the 4 listed tempers.
Is 50Cr-50Ni-Cb-AC easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 86% of refractory metal grades). Very difficult and abrasive — use rigid setups, ceramic or coated-carbide inserts, low speed with heavy positive feed, flood coolant; grinding or EDM for finish features on hard duplex structure.
Can 50Cr-50Ni-Cb-AC be welded?
Not readily — weldability is rated poor (25/100). GTAW/SMAW with matching 50Cr-50Ni-Nb filler only, low heat input, interpass temperature control and minimal restraint; highly sensitive to hot cracking and post-service embrittlement, so field repair of aged parts is generally not recommended.
What surface finishes work on 50Cr-50Ni-Cb-AC?
Service protection comes from the self-forming Cr₂O₃ scale; shot blast or pickle to remove casting scale, no plating or anodizing needed and paint is pointless at service temperature.
Can 50Cr-50Ni-Cb-AC be formed, bent or molded?
Not cold formable — parts are produced as sand or investment castings (air or vacuum melt); allow generous fillets and controlled solidification to avoid shrinkage porosity.
What is the maximum service temperature of 50Cr-50Ni-Cb-AC?
50Cr-50Ni-Cb-AC is rated for continuous use to about 1,100°C (2,012 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 50Cr-50Ni-Cb-AC and 50Cr-50Ni-Cb-HIP?
AC is the default condition — standard supply condition for sand/investment castings — tube supports, hangers, burner parts for fuel-ash corrosion service. HIP: specify for critical, thermally cycled or pressure-containing castings where shrinkage porosity must be closed to raise ductility and creep life. Yield strength is 390 MPa in AC versus 400 MPa in HIP.
Sources
- ASTM A560/A560M — Castings, Chromium-Nickel Alloy — ASTM International (2020)
- IN-657 (50Cr-50Ni-Nb) alloy data for fuel-ash corrosion resistance — Special Metals / Inco-type producer literature (2004)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 13B — Corrosion: Materials (high-temperature fuel-ash corrosion) — ASM International (2005)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.