Refractory Metal 50Cr-50Ni-SR (Stress relieved)
Heat-treated state
UNS R20500 · ASTM A560 Gr 50Cr-50Ni
Pick when complex castings or weld repairs need residual stress removed before machining or thermal cycling service.
Values for the SR condition
Other 50Cr-50Ni tempers and conditions
50Cr-50Ni is listed in 3 conditions; see the grade overview at 50Cr-50Ni.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
SRThis page Stress relieved | Pick when complex castings or weld repairs need residual stress removed before machining or thermal cycling service. | 310 | 520 | 12 | 17 HRC | 1.7 % IACS |
As-welded deposit | Condition of 50Cr-50Ni filler deposited as cladding on boiler supports and incinerator walls; expect low ductility and mandatory preheat. | 330 | 480 | 4 | 23 HRC | 1.7 % IACS |
FDefault As fabricated | Standard supply condition for ASTM A560 castings; use for boiler tube supports and incinerator hardware where only high-temperature corrosion resistance matters. | 340 | 550 | 8 | 20 HRC | 1.7 % IACS |
What is 50Cr-50Ni-SR?
50Cr-50Ni-SR is 50Cr-50Ni heat treated to SR — pick when complex castings or weld repairs need residual stress removed before machining or thermal cycling service. 50Cr-50Ni-SR has a yield strength of 310 MPa (45 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 55% of refractory metal grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi). 50Cr-50Ni-SR has a density of 7.85 g/cm³ (0.284 lb/in³), lighter than 53% of refractory metal grades. It melts at 1,390°C (2,534 °F). F is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Low embodied carbon — 9.5 kg CO₂/kg, better than 91% of refractory metal grades
Limitations
- Hard to polish — 45/100, worse than 98% of refractory metal grades
- Low electrical conductivity — 1.7 % IACS, worse than 93% 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 — 18/100, worse than 80% of refractory metal grades
50Cr-50Ni-SR properties
Typical room-temperature values for 50Cr-50Ni-SR; 23 are specific to this condition. Other listed values are 50Cr-50Ni reference data and may not represent this condition. Bars are the position among refractory metal grades.
Physical3
50Cr-50Ni-SR has a density of 7.85 g/cm³ (0.284 lb/in³), lighter than 53% of refractory metal grades. It melts at 1,390°C (2,534 °F).
Mechanical17
50Cr-50Ni-SR has a yield strength of 310 MPa (45 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 55% of refractory metal grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi).
Thermal5
50Cr-50Ni-SR 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-SR conducts electricity at 1.7 % IACS, worse than 93% of refractory metal grades.
Chemical & Environmental3
Corrosion resistance is excellent (86/100), better than 59% of refractory metal grades.
Sustainability4
Producing a kilogram of 50Cr-50Ni-SR takes about 100 MJ of energy and emits 9.5 kg of CO₂ — less than 93% of refractory metal grades. Typical recycled content is 20%.
Manufacturability8
50Cr-50Ni-SR's machinability is poor (18/100, worse than 80% of refractory metal grades); weldability poor (25/100); formability not recommended (8/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 50Cr-50Ni-SR
Is 50Cr-50Ni easy to machine?
Hard, abrasive duplex structure — use rigid setups, negative-rake carbide or ceramic inserts, low speed and heavy flood coolant; grinding is often preferred for finish surfaces.
Can 50Cr-50Ni be welded?
Weldable only with matching 50Cr-50Ni(-Nb) filler using GTAW/SMAW, 200–300 °C preheat, low heat input and slow cooling; highly crack-sensitive, so avoid restrained joints.
Can 50Cr-50Ni be formed, bent or molded?
Not cold formable — produced exclusively as static, centrifugal or investment castings; allow generous fillets and controlled solidification to avoid hot tears.
What surface finishes work on 50Cr-50Ni?
Relies on its self-forming Cr2O3 scale; blast or pickle castings clean, no anodizing or plating is used, and painting is unnecessary for high-temperature service.
50Cr-50Ni 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 |
|---|---|---|
| Cr | 48 – 52 | 50 |
| C | ≤ 0.1 | 0.05 |
| Si | ≤ 1 | 0.5 |
| Mn | ≤ 0.3 | 0.15 |
| Fe | ≤ 1 | 0.5 |
| Al | ≤ 0.25 | 0.1 |
| Ti | ≤ 0.5 | 0.1 |
| N | ≤ 0.16 | 0.05 |
| P | ≤ 0.02 | — |
| S | ≤ 0.02 | — |
| Nibalance, nominally ~48–50 % | balance | — |
50Cr-50Ni-SR — frequently asked
What is 50Cr-50Ni-SR used for?
50Cr-50Ni-SR is typically used for heat-treating furnace fixtures, radiant tubes, trays and baskets for carburizing and high-temperature process equipment. In short: best carburization resistance; cast-only furnace alloy; very difficult to machine.
What is the yield strength of 50Cr-50Ni-SR?
50Cr-50Ni-SR has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 55% of refractory metal grades. Strength varies by condition: see the 3 listed tempers.
Is 50Cr-50Ni-SR easy to machine?
Not especially — machinability is rated poor (18/100, worse than 80% of refractory metal grades). Hard, abrasive duplex structure — use rigid setups, negative-rake carbide or ceramic inserts, low speed and heavy flood coolant; grinding is often preferred for finish surfaces.
Can 50Cr-50Ni-SR be welded?
Not readily — weldability is rated poor (25/100). Weldable only with matching 50Cr-50Ni(-Nb) filler using GTAW/SMAW, 200–300 °C preheat, low heat input and slow cooling; highly crack-sensitive, so avoid restrained joints.
What surface finishes work on 50Cr-50Ni-SR?
Relies on its self-forming Cr2O3 scale; blast or pickle castings clean, no anodizing or plating is used, and painting is unnecessary for high-temperature service.
Can 50Cr-50Ni-SR be formed, bent or molded?
Not cold formable — produced exclusively as static, centrifugal or investment castings; allow generous fillets and controlled solidification to avoid hot tears.
What is the maximum service temperature of 50Cr-50Ni-SR?
50Cr-50Ni-SR 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-F and 50Cr-50Ni-SR?
F is the default condition — standard supply condition for ASTM A560 castings; use for boiler tube supports and incinerator hardware where only high-temperature corrosion resistance matters. SR: pick when complex castings or weld repairs need residual stress removed before machining or thermal cycling service. Yield strength is 340 MPa in F versus 310 MPa in SR.
Sources
- ASTM A560/A560M — Standard Specification for Castings, Chromium-Nickel Alloy — ASTM International (2021)
- ASM Handbook Vol. 1: Properties and Selection — Heat-Resistant Castings — ASM International (1990)
- ASM Handbook Vol. 13B: Corrosion — Materials for High-Temperature Fuel-Ash Corrosion — ASM International (2005)
- IN-657 / 50Cr-50Ni-Nb alloy technical bulletin — Special Metals / Inco (2004)
- UNS R20500 alloy record — SAE/ASTM Metals & Alloys in the Unified Numbering System (2017)
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.