Cobalt-Chrome Alloy ERCoCr-B-SR (Stress relieved)
Heat-treated state
UNS R30006
Choose when the substrate (e.g. Cr-Mo steel) requires PWHT or when overlay cracking risk on thick sections must be reduced; overlay hardness is essentially unchanged or slightly higher from carbide precipitation.
Values for the SR condition
Other ERCoCr-B tempers and conditions
ERCoCr-B is listed in 3 conditions; see the grade overview at ERCoCr-B.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AWDefault As-welded deposit | Standard reference condition: fully undiluted Co-Cr-W overlay as deposited by GTAW/PTA/oxy-fuel, no post-weld heat treatment. | 620 | 830 | 1 | 45 HRC | 2 % IACS |
As cast | Solid cast parts (valve trim, nozzles, wear inserts) made to the same Co-Cr-W chemistry when a full-section wear alloy rather than an overlay is required. | 620 | 830 | 1 | 46 HRC | 2 % IACS |
SRThis page Stress relieved | Choose when the substrate (e.g. Cr-Mo steel) requires PWHT or when overlay cracking risk on thick sections must be reduced; overlay hardness is essentially unchanged or slightly higher from carbide precipitation. | 640 | 830 | 1 | 46 HRC | 2 % IACS |
What is ERCoCr-B-SR?
ERCoCr-B-SR is ERCoCr-B heat treated to SR — choose when the substrate (e.g. Cr-Mo steel) requires PWHT or when overlay cracking risk on thick sections must be reduced; overlay hardness is essentially unchanged or slightly higher from carbide precipitation. ERCoCr-B-SR has a yield strength of 640 MPa (92.8 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 77% of cobalt-chrome alloy grades. Elongation at break is 1% and the elastic modulus is 228 GPa (33.1 Msi). ERCoCr-B-SR has a density of 8.6 g/cm³ (0.311 lb/in³), heavier than 63% of cobalt-chrome alloy grades. It melts at 1,280°C (2,336 °F). AW 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 87% of cobalt-chrome alloy grades
Limitations
- Low fracture toughness — 10 MPa·√m (9.1 ksi·√in), worse than 100% of cobalt-chrome alloy grades
ERCoCr-B-SR properties
Typical room-temperature values for ERCoCr-B-SR; 22 are specific to this condition. Other listed values are ERCoCr-B reference data and may not represent this condition. Bars are the position among cobalt-chrome alloy grades.
Physical3
ERCoCr-B-SR has a density of 8.6 g/cm³ (0.311 lb/in³), heavier than 63% of cobalt-chrome alloy grades. It melts at 1,280°C (2,336 °F).
Mechanical16
ERCoCr-B-SR has a yield strength of 640 MPa (92.8 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 77% of cobalt-chrome alloy grades. Elongation at break is 1% and the elastic modulus is 228 GPa (33.1 Msi).
Thermal5
ERCoCr-B-SR is rated for continuous service to 800°C (1,472 °F). It conducts heat at 14.5 W/m·K (8.38 BTU/hr·ft·°F), better than 64% of cobalt-chrome alloy grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
ERCoCr-B-SR conducts electricity at 2 % IACS, better than 79% of cobalt-chrome alloy grades.
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 71% of cobalt-chrome alloy grades.
Sustainability4
Producing a kilogram of ERCoCr-B-SR takes about 130 MJ of energy and emits 9.5 kg of CO₂ — less than 89% of cobalt-chrome alloy grades. Typical recycled content is 20%.
Manufacturability7
ERCoCr-B-SR's machinability is not recommended (7/100, worse than 75% of cobalt-chrome alloy grades); weldability fair (35/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ERCoCr-B-SR
Is ERCoCr-B easy to machine?
Finish by grinding (SiC/CBN wheels) or lapping; if turning is unavoidable use negative-rake carbide/ceramic, rigid setup, low speed and heavy feed — no HSS tooling.
Can ERCoCr-B be welded?
Deposit with GTAW, oxy-acetylene, PTA or laser cladding; preheat 300–500 °C for steel substrates, keep interpass hot, limit dilution and cool slowly under insulation — some transverse check cracking is normal and generally acceptable.
Can ERCoCr-B be formed, bent or molded?
Not formable: the deposit is a hard hypereutectic carbide structure with ~1 % elongation, so all shaping is done by weld deposition, casting or grinding.
What surface finishes work on ERCoCr-B?
Grinds and laps to a mirror sealing face with excellent gall resistance; no plating or coating is needed, and passivation/pickling is only for cleanup of weld oxide.
ERCoCr-B 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 |
|---|---|---|
| Chigher than ERCoCr-A, gives more Cr-W carbide | 1 – 1.7 | 1.35 |
| Cr | 26 – 32 | 29 |
| W | 7 – 9.5 | 8.3 |
| Ni | ≤ 3 | — |
| Femax (undiluted deposit / filler analysis) | ≤ 3 | — |
| Si | ≤ 2 | 1 |
| Mn | ≤ 2 | 0.5 |
| Mo | ≤ 1 | — |
| Other, total | ≤ 1 | — |
| Co | balance | — |
ERCoCr-B-SR — frequently asked
What is ERCoCr-B-SR used for?
ERCoCr-B-SR is typically used for valve seat overlay welding, pump sleeves and steam turbine wear surfaces. In short: most-used cobalt hardfacing filler; balanced wear and corrosion; stellite 6 equivalent deposit.
What is the yield strength of ERCoCr-B-SR?
ERCoCr-B-SR has a typical yield strength of 640 MPa (92.8 ksi) and a tensile strength of 830 MPa (120 ksi) — stronger than 77% of cobalt-chrome alloy grades. Strength varies by condition: see the 3 listed tempers.
Is ERCoCr-B-SR easy to machine?
Not especially — machinability is rated not recommended (7/100, worse than 75% of cobalt-chrome alloy grades). Finish by grinding (SiC/CBN wheels) or lapping; if turning is unavoidable use negative-rake carbide/ceramic, rigid setup, low speed and heavy feed — no HSS tooling.
Can ERCoCr-B-SR be welded?
With care — weldability is rated fair (35/100). Deposit with GTAW, oxy-acetylene, PTA or laser cladding; preheat 300–500 °C for steel substrates, keep interpass hot, limit dilution and cool slowly under insulation — some transverse check cracking is normal and generally acceptable.
What surface finishes work on ERCoCr-B-SR?
Grinds and laps to a mirror sealing face with excellent gall resistance; no plating or coating is needed, and passivation/pickling is only for cleanup of weld oxide.
Can ERCoCr-B-SR be formed, bent or molded?
Not formable: the deposit is a hard hypereutectic carbide structure with ~1 % elongation, so all shaping is done by weld deposition, casting or grinding.
What is the maximum service temperature of ERCoCr-B-SR?
ERCoCr-B-SR is rated for continuous use to about 800°C (1,472 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between ERCoCr-B-AW and ERCoCr-B-SR?
AW is the default condition — standard reference condition: fully undiluted Co-Cr-W overlay as deposited by GTAW/PTA/oxy-fuel, no post-weld heat treatment. SR: choose when the substrate (e.g. Cr-Mo steel) requires PWHT or when overlay cracking risk on thick sections must be reduced; overlay hardness is essentially unchanged or slightly higher from carbide precipitation. Yield strength is 620 MPa in AW versus 640 MPa in SR.
Sources
- AWS A5.21/A5.21M — Specification for Bare Electrodes and Rods for Surfacing — American Welding Society (2021)
- ASM Handbook Vol. 2 — Properties and Selection: Nonferrous Alloys (Cobalt Wear-Resistant Alloys) — ASM International (1990)
- ASM Handbook Vol. 6 — Welding, Brazing and Soldering (Hardfacing) — ASM International (1993)
- Stellite 12 alloy technical data (rod, wire, powder) — Kennametal Stellite / Deloro (2023)
- UNS R30012 / R30006 alloy designations (Metals & Alloys in the Unified Numbering System) — SAE/ASTM (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.