Stainless Steel HN
UNS J94213
HN is a higher-nickel heat-resistant cast stainless steel (UNS J94213) to ASTM A297 and A743, available as-cast, centrifugally cast as HN40-CENT, or aged.
Reference datasheet — HN is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the AS-CAST condition
HN tempers and conditions
HN is supplied in 3 conditions, soft to hard. AS-CAST is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AS-CASTDefault no heat treatment, ASTM A297/A743 HN | Standard supply condition for HN furnace hardware; use for all high-temperature service where creep and carburization resistance matter. | 255 | 470 | 11 | 175 HB | — |
HN40 centrifugally cast tube | Choose for radiant tubes, reformer/carburizing furnace tubes: centrifugal casting gives a denser, finer columnar structure and slightly higher strength than static castings. | 275 | 500 | 10 | 185 HB | 1.7 % IACS |
Aged / service-exposed | Reference condition for assessing repair or re-use of furnace parts after prolonged high-temperature service: strength rises slightly, room-temperature ductility and impact energy collapse. | 310 | 490 | 4 | 200 HB | 1.8 % IACS |
What is HN?
HN is a higher-nickel heat-resistant cast stainless steel (UNS J94213) to ASTM A297 and A743, available as-cast, centrifugally cast as HN40-CENT, or aged. The added nickel improves carburization and thermal-fatigue resistance compared with HK, which is why it is used for cyclically heated carburizing-furnace hardware; default properties are 255 MPa yield, 470 MPa tensile, 11% elongation, 175 HB (88 HRB) and service to about 1090 °C. Room-temperature strength is lower than HK and the alloy is castings-only with no forming route. HP is the next step for higher creep-rupture strength. HN has a density of 7.83 g/cm³ (0.283 lb/in³), heavier than 58% of stainless steel grades. It melts at 1,315°C (2,399 °F). HN has a yield strength of 255 MPa (37 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 11% and the elastic modulus is 180 GPa (26.1 Msi).
What is HN used for?
- carburizing furnace fixtures
- radiant tubes
- heat-treatment baskets
Advantages
- High service temperature — 1,090°C (1,994 °F), better than 93% of stainless steel grades
Limitations
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Limited ductility — 11%, worse than 96% of stainless steel grades
- Hard to polish — 45/100, worse than 96% of stainless steel grades
- Low electrical conductivity — 1.7 % IACS, worse than 93% of stainless steel grades
- Poor heat conductor — 12.5 W/m·K (7.22 BTU/hr·ft·°F), worse than 90% of stainless steel grades
HN properties
Typical room-temperature values for HN-AS-CAST; bars are the position among stainless steel grades.
Physical3
HN has a density of 7.83 g/cm³ (0.283 lb/in³), heavier than 58% of stainless steel grades. It melts at 1,315°C (2,399 °F).
Mechanical14
HN has a yield strength of 255 MPa (37 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 87% of stainless steel grades. Elongation at break is 11% and the elastic modulus is 180 GPa (26.1 Msi).
Thermal6
HN is rated for continuous service to 1,090°C (1,994 °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 15.5 µm/m·K (8.61 µin/in·°F).
Electrical3
HN conducts electricity at 1.7 % IACS, worse than 93% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 58% of stainless steel grades.
Sustainability4
Producing a kilogram of HN takes about 60 MJ of energy and emits 5 kg of CO₂ — more than 70% of stainless steel grades. Typical recycled content is 65%.
Manufacturability7
HN's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability fair (40/100); formability not recommended (5/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. HN is highlighted; hover a dot for its name, or open the interactive family chart.
Working with HN
Is HN easy to machine?
Machine with rigid setups, sharp carbide inserts, low speed / heavy positive feed and flood coolant; the massive carbide network and rapid work hardening make interrupted cuts and small drills the main failure modes — grind rather than turn hardened service-aged parts.
Can HN be welded?
Weldable by SMAW/GTAW/FCAW with matching HN or 25Cr-35Ni filler; preheat 150–250 °C, low heat input and slow cool to limit hot cracking, and expect drastically reduced ductility when welding parts already thermally aged (solution treat at ~1100 °C first if possible).
Can HN be formed, bent or molded?
Casting-only grade — sand, investment and centrifugal casting all practical; feed heavy sections generously, avoid abrupt section changes to control hot tearing, and design generous fillets since no cold forming or straightening is possible.
HN 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 |
|---|---|---|
| CHN40 subgrade (A608) narrows to 0.35–0.45 | 0.2 – 0.5 | 0.35 |
| Cr | 19 – 23 | 21 |
| Ni | 23 – 27 | 25 |
| Mn | ≤ 2 | 1.2 |
| Simax; higher Si aids oxidation resistance | ≤ 2 | 1.4 |
| Moresidual, max | ≤ 0.5 | 0.1 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.04 | 0.02 |
| Fe | balance |
What surface finishes work on HN?
Normally supplied shot-blasted or pickled; a self-healing Cr₂O₃/spinel scale forms in service and needs no coating, but aluminizing or diffusion coatings can be applied for severe carburizing/sulphidizing duty.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Passivation
Organic Coating
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel HN in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J94213
How much does HN cost?
HN is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
HN — frequently asked
What is HN used for?
HN is typically used for carburizing furnace fixtures, radiant tubes and heat-treatment baskets. In short: best carburization resistance vs HK; good thermal-fatigue life; lower strength, higher nickel.
What is the yield strength of HN?
HN has a typical yield strength of 255 MPa (37 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 87% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is HN easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Machine with rigid setups, sharp carbide inserts, low speed / heavy positive feed and flood coolant; the massive carbide network and rapid work hardening make interrupted cuts and small drills the main failure modes — grind rather than turn hardened service-aged parts.
Can HN be welded?
With care — weldability is rated fair (40/100). Weldable by SMAW/GTAW/FCAW with matching HN or 25Cr-35Ni filler; preheat 150–250 °C, low heat input and slow cool to limit hot cracking, and expect drastically reduced ductility when welding parts already thermally aged (solution treat at ~1100 °C first if possible).
What surface finishes work on HN?
Normally supplied shot-blasted or pickled; a self-healing Cr₂O₃/spinel scale forms in service and needs no coating, but aluminizing or diffusion coatings can be applied for severe carburizing/sulphidizing duty.
Can HN be formed, bent or molded?
Casting-only grade — sand, investment and centrifugal casting all practical; feed heavy sections generously, avoid abrupt section changes to control hot tearing, and design generous fillets since no cold forming or straightening is possible.
What is the maximum service temperature of HN?
HN 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 HN AS-CAST and HN Aged?
AS-CAST is the default condition — standard supply condition for HN furnace hardware; use for all high-temperature service where creep and carburization resistance matter. Aged: reference condition for assessing repair or re-use of furnace parts after prolonged high-temperature service: strength rises slightly, room-temperature ductility and impact energy collapse. Yield strength is 255 MPa in AS-CAST versus 310 MPa in Aged.
How much does HN cost?
HN is a high-cost stainless steel ($$$$), pricier than about 78% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- ASTM A297/A297M — Steel Castings, Iron-Chromium and Iron-Chromium-Nickel, Heat Resistant, for General Application — ASTM International (2019)
- ASTM A743/A743M — Castings, Iron-Chromium, Iron-Chromium-Nickel, Corrosion Resistant, for General Application — ASTM International (2019)
- ASTM A608/A608M — Centrifugally Cast Iron-Chromium-Nickel High-Alloy Tubing for Pressure Application at High Temperatures (grade HN40) — ASTM International (2018)
- Steel Castings Handbook, Supplement 9 — High Alloy Data Sheets, Heat Series — Steel Founders' Society of America (2004)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (heat-resistant castings) — ASM International (1990)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.