Stainless Steel HC Aged
Heat-treated state
UNS J92605 · ASTM A297 Grade HC
Aged = after prolonged high-temperature service exposure
Design reference for parts already in service: strength holds up but room-temperature toughness and ductility collapse from sigma-phase and 475 °C embrittlement.
Values for the Aged condition
Other HC tempers and conditions
HC is listed in 4 conditions; see the grade overview at HC.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Stress relieved | Choose for dimensionally critical or heavily machined castings to relieve casting and welding stresses; slightly softer, marginally more ductile. | 420 | 640 | 14 | 195 HB | 2.2 % IACS |
FDefault As fabricated | Standard supply condition for furnace hardware; used directly after cleaning and stress relief of risers. | 450 | 690 | 12 | 205 HB | 2.2 % IACS |
Centrifugally cast | Pick for radiant tubes, rolls and cylindrical retorts needing sounder, finer-grained walls than static sand castings. | 470 | 720 | 14 | 210 HB | 2.2 % IACS |
AgedThis page After prolonged high-temperature service exposure | Design reference for parts already in service: strength holds up but room-temperature toughness and ductility collapse from sigma-phase and 475 °C embrittlement. | 520 | 720 | 2 | 20 HRC | 2.2 % IACS |
What is HC Aged?
HC Aged is HC heat treated to Aged — design reference for parts already in service: strength holds up but room-temperature toughness and ductility collapse from sigma-phase and 475 °C embrittlement. HC Aged has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 79% of stainless steel grades. Elongation at break is 2% and the elastic modulus is 200 GPa (29 Msi). HC Aged has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 98% of stainless steel grades. It melts at 1,385°C (2,525 °F). F is the default condition FabDigit quotes; Aged is available on request or by drawing note.
Advantages
- High service temperature — 1,090°C (1,994 °F), better than 93% of stainless steel grades
- High strength — 520 MPa (75.4 ksi), better than 79% of stainless steel grades
- Low embodied carbon — 3.8 kg CO₂/kg, better than 77% of stainless steel grades
- Conducts heat well — 21 W/m·K (12.1 BTU/hr·ft·°F), better than 76% of stainless steel grades
Limitations
- Limited ductility — 2%, worse than 100% of stainless steel grades
- Limited formability — 2/100, worse than 100% of stainless steel grades
- Difficult to weld — 15/100, worse than 98% of stainless steel grades
- Hard to polish — 45/100, worse than 96% of stainless steel grades
HC Aged properties
Typical room-temperature values for HC Aged; 23 are specific to this condition. Other listed values are HC reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
HC Aged has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 98% of stainless steel grades. It melts at 1,385°C (2,525 °F).
Mechanical15
HC Aged has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 79% of stainless steel grades. Elongation at break is 2% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
HC Aged is rated for continuous service to 1,090°C (1,994 °F). It conducts heat at 21 W/m·K (12.1 BTU/hr·ft·°F), better than 76% of stainless steel grades. Thermal expansion is 10.8 µm/m·K (6 µin/in·°F).
Electrical3
HC Aged conducts electricity at 2.2 % IACS, worse than 61% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of HC Aged takes about 55 MJ of energy and emits 3.8 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
HC Aged's machinability is poor (26/100, worse than 84% of stainless steel grades); weldability poor (15/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with HC Aged
Is HC easy to machine?
Machine with rigid setups, sharp carbide tooling, low speed and heavy positive feed to cut under the abrasive Cr-carbide network; avoid dwelling to prevent work hardening.
Can HC be welded?
Weldable with 26Cr-type or high-Ni (ERNiCr) filler using 150–260 °C preheat, low heat input and post-weld anneal near 790 °C to restore some ductility; expect brittle coarse-grained HAZ.
Can HC be formed, bent or molded?
A casting alloy only — sand and investment cast with generous fillets and controlled solidification; no cold forming, and hot working is impractical.
What surface finishes work on HC?
Shot-blast or pickle plus passivate for scale removal; leave uncoated for furnace service since the self-forming chromia scale is the protective layer — painting and plating are pointless above 500 °C.
HC 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 |
|---|---|---|
| CASTM A297 max | ≤ 0.5 | 0.35 |
| Cr | 26 – 30 | 28 |
| Ni | ≤ 4 | 1.5 |
| Si | ≤ 2 | 1.2 |
| Mn | ≤ 1 | 0.7 |
| Moresidual, not intentionally added | ≤ 0.5 | — |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Fe | balance | — |
HC Aged — frequently asked
What is HC Aged used for?
HC Aged is typically used for furnace parts, combustion chamber components, heat treatment fixtures and kiln hardware. In short: low-nickel heat-resisting casting; 1090 °C oxidizing service; brittle after thermal exposure.
What is the yield strength of HC Aged?
HC Aged has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 720 MPa (104 ksi) — stronger than 79% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is HC Aged easy to machine?
Not especially — machinability is rated poor (26/100, worse than 84% of stainless steel grades). Machine with rigid setups, sharp carbide tooling, low speed and heavy positive feed to cut under the abrasive Cr-carbide network; avoid dwelling to prevent work hardening.
Can HC Aged be welded?
Not readily — weldability is rated poor (15/100). Weldable with 26Cr-type or high-Ni (ERNiCr) filler using 150–260 °C preheat, low heat input and post-weld anneal near 790 °C to restore some ductility; expect brittle coarse-grained HAZ.
What surface finishes work on HC Aged?
Shot-blast or pickle plus passivate for scale removal; leave uncoated for furnace service since the self-forming chromia scale is the protective layer — painting and plating are pointless above 500 °C.
Can HC Aged be formed, bent or molded?
A casting alloy only — sand and investment cast with generous fillets and controlled solidification; no cold forming, and hot working is impractical.
What is the maximum service temperature of HC Aged?
HC Aged is rated for continuous use to about 1,090°C (1,994 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between HC-F and HC Aged?
F is the default condition — standard supply condition for furnace hardware; used directly after cleaning and stress relief of risers. Aged: design reference for parts already in service: strength holds up but room-temperature toughness and ductility collapse from sigma-phase and 475 °C embrittlement. Yield strength is 450 MPa in F versus 520 MPa in Aged.
Sources
- ASTM A297/A297M — Steel Castings, Iron-Chromium and Iron-Chromium-Nickel, Heat Resistant, for General Application — ASTM International (2019)
- ASTM A608/A608M — Centrifugally Cast Iron-Chromium-Nickel High-Alloy Tubing for Pressure Application at High Temperatures — ASTM International (2018)
- ASM Specialty Handbook: Heat-Resistant Materials — Cast Heat-Resistant Alloys (ACI H-series) — ASM International (1997)
- ASM Handbook Vol.1 — Cast Stainless Steels — ASM International (1990)
- Steel Founders' Society of America — High Alloy Data Sheets, Heat Series — SFSA (2004)
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.