Stainless Steel HT AS-CAST
Heat-treated state · default condition
UNS N08605
Standard supply condition for furnace fixtures and trays; used as-cast because service temperature exceeds any heat-treat benefit.
Values for the AS-CAST condition
Other HT tempers and conditions
HT is listed in 4 conditions; see the grade overview at HT.
Compare all 4 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ASTM A351 low-carbon (0.25–0.35 C) pressure-casting version | Pick when the casting is a pressure-containing part needing better ductility and weld repair tolerance than full-carbon HT. | 240 | 485 | 15 | 170 HB | 1.7 % IACS |
AS-CASTDefaultThis page sand/investment cast, no post-cast heat treatment | Standard supply condition for furnace fixtures and trays; used as-cast because service temperature exceeds any heat-treat benefit. | 275 | 485 | 10 | 180 HB | 1.7 % IACS |
HT50, centrifugally cast tube | Choose for radiant tubes and furnace rolls where a dense, directionally solidified centrifugal tube wall is required. | 275 | 500 | 12 | 185 HB | 1.7 % IACS |
Aged / service-exposed | Use these numbers when designing for room-temperature handling loads on parts that have already seen furnace service. | 310 | 515 | 4 | 200 HB | 1.8 % IACS |
What is HT AS-CAST?
HT AS-CAST is HT heat treated to AS-CAST — standard supply condition for furnace fixtures and trays; used as-cast because service temperature exceeds any heat-treat benefit. HT AS-CAST has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 485 MPa (70.3 ksi) — weaker than 77% of stainless steel grades. Elongation at break is 10% and the elastic modulus is 175 GPa (25.4 Msi). HT AS-CAST has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,340°C (2,444 °F).
Advantages
- High service temperature — 1,100°C (2,012 °F), better than 96% of stainless steel grades
Limitations
- Low stiffness — 175 GPa (25.4 Msi), worse than 99% of stainless steel grades
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Hard to polish — 40/100, worse than 99% of stainless steel grades
- Limited ductility — 10%, worse than 98% of stainless steel grades
- Low electrical conductivity — 1.7 % IACS, worse than 93% of stainless steel grades
HT AS-CAST properties
Typical room-temperature values for HT AS-CAST; 20 are specific to this condition. Other listed values are HT reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
HT AS-CAST has a density of 7.9 g/cm³ (0.285 lb/in³), heavier than 68% of stainless steel grades. It melts at 1,340°C (2,444 °F).
Mechanical14
HT AS-CAST has a yield strength of 275 MPa (39.9 ksi) and a tensile strength of 485 MPa (70.3 ksi) — weaker than 77% of stainless steel grades. Elongation at break is 10% and the elastic modulus is 175 GPa (25.4 Msi).
Thermal5
HT AS-CAST is rated for continuous service to 1,100°C (2,012 °F). It conducts heat at 12.5 W/m·K (7.22 BTU/hr·ft·°F), worse than 90% of stainless steel grades. Thermal expansion is 14.7 µm/m·K (8.17 µin/in·°F).
Electrical3
HT AS-CAST conducts electricity at 1.7 % IACS, worse than 93% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (55/100), worse than 71% of stainless steel grades.
Sustainability4
Producing a kilogram of HT AS-CAST takes about 78 MJ of energy and emits 5.6 kg of CO₂ — more than 87% of stainless steel grades. Typical recycled content is 60%.
Manufacturability8
HT AS-CAST's machinability is poor (25/100, worse than 88% of stainless steel grades); weldability fair (35/100); formability not recommended (5/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with HT AS-CAST
Is HT easy to machine?
Difficult — abrasive primary carbides and rapid work hardening; use rigid setups, carbide/ceramic tooling, low speed with heavy positive feed and flood coolant, avoid dwelling.
Can HT be welded?
Weldable with matching HT (35Ni) or Ni-base (ERNiCr-3) filler; preheat 150–260 °C, low heat input, and expect reduced repair weldability on service-exposed (carburized/sigma-embrittled) parts.
Can HT be formed, bent or molded?
Cast-only alloy — no cold forming; design generous fillets, uniform sections and adequate risers because of the wide freezing range and high solidification shrinkage.
What surface finishes work on HT?
Normally supplied shot-blasted and ground at gates; no anodizing/plating — the protective Cr/Ni oxide scale forms in service, so avoid contaminating surfaces with sulfur or zinc-bearing compounds.
HT 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 |
|---|---|---|
| C0.25–0.35 for A351 HT30 | 0.35 – 0.75 | 0.5 |
| Mn | ≤ 2 | 1.2 |
| Sihigh Si aids carburization resistance | ≤ 2.5 | 1.6 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Cr | 15 – 19 | 17 |
| Ni | 33 – 37 | 35 |
| Moresidual, not intentionally added | ≤ 0.5 | — |
| Fe | balance | — |
HT AS-CAST — frequently asked
What is HT AS-CAST used for?
HT AS-CAST is typically used for carburizing furnace fixtures, radiant tubes and heat-treatment retorts. In short: best carburization resistance; 1100 °C cast grade; cast-only, hard to machine.
What is the yield strength of HT AS-CAST?
HT AS-CAST has a typical yield strength of 275 MPa (39.9 ksi) and a tensile strength of 485 MPa (70.3 ksi) — weaker than 77% of stainless steel grades. Strength varies by condition: see the 4 listed tempers.
Is HT AS-CAST easy to machine?
Not especially — machinability is rated poor (25/100, worse than 88% of stainless steel grades). Difficult — abrasive primary carbides and rapid work hardening; use rigid setups, carbide/ceramic tooling, low speed with heavy positive feed and flood coolant, avoid dwelling.
Can HT AS-CAST be welded?
With care — weldability is rated fair (35/100). Weldable with matching HT (35Ni) or Ni-base (ERNiCr-3) filler; preheat 150–260 °C, low heat input, and expect reduced repair weldability on service-exposed (carburized/sigma-embrittled) parts.
What surface finishes work on HT AS-CAST?
Normally supplied shot-blasted and ground at gates; no anodizing/plating — the protective Cr/Ni oxide scale forms in service, so avoid contaminating surfaces with sulfur or zinc-bearing compounds.
Can HT AS-CAST be formed, bent or molded?
Cast-only alloy — no cold forming; design generous fillets, uniform sections and adequate risers because of the wide freezing range and high solidification shrinkage.
What is the maximum service temperature of HT AS-CAST?
HT AS-CAST 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 HT AS-CAST and HT Aged?
AS-CAST is the default condition — standard supply condition for furnace fixtures and trays; used as-cast because service temperature exceeds any heat-treat benefit. Aged: use these numbers when designing for room-temperature handling loads on parts that have already seen furnace service. Yield strength is 275 MPa in AS-CAST versus 310 MPa in Aged.
Sources
- ASTM A297/A297M — Steel Castings, Iron-Chromium and Iron-Chromium-Nickel, Heat Resistant, for General Application — ASTM International (2019)
- ASTM A351/A351M — Castings, Austenitic, for Pressure-Containing Parts — ASTM International (2018)
- ASTM A608/A608M — Centrifugally Cast Iron-Chromium-Nickel High-Alloy Tubing for Pressure Application at High Temperatures — ASTM International (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (Heat-Resistant Castings) — ASM International (1990)
- Steel Castings Handbook, 6th ed. — High Alloy Data Sheets, Heat Series — Steel Founders' Society of America / ASM (1995)
- ASM Handbook Vol.13B — Corrosion: Materials (high-temperature corrosion of cast Fe-Cr-Ni alloys) — 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.