Stainless Steel HD
UNS J93005 · ASTM A297 Grade HD
HD (UNS J93005, ASTM A297 Grade HD) is a 28Cr-5Ni heat-resistant cast alloy that adds nickel to Grade HC for higher high-temperature strength, used for furnace fixtures and radiant tube supports in oxidizing environments to 1090 °C.
Reference datasheet — HD 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 F condition
HD tempers and conditions
HD is supplied in 3 conditions, soft to hard. F 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 |
|---|---|---|---|---|---|---|
Solution annealed ~1040–1065 °C, rapid cool | Optional treatment used to dissolve grain-boundary carbides and re-solution sigma phase, giving the best available room-temperature ductility before machining or welding. | 320 | 560 | 18 | 180 HB | 2.1 % IACS |
FDefault As fabricated | Standard supply condition for all A297 HD castings; no heat treatment is required or normally applied. | 345 | 585 | 16 | 12 HRC | 2 % IACS |
Aged / service-exposed | Represents the embrittled condition after prolonged exposure in the 600–900 °C range; use these values for design checks on repair, handling and thermal-cycling loads. | 415 | 655 | 4 | 20 HRC | 2 % IACS |
What is HD?
HD (UNS J93005, ASTM A297 Grade HD) is a 28Cr-5Ni heat-resistant cast alloy that adds nickel to Grade HC for higher high-temperature strength, used for furnace fixtures and radiant tube supports in oxidizing environments to 1090 °C. Typical properties are 345 MPa yield, 585 MPa tensile, 16% elongation and 190 HB (90 HRB); it is supplied as-cast, solution annealed or aged as sand and investment castings. It is a casting grade only, the Cr carbides are abrasive to machine, and as-cast or aged material is crack-sensitive during welding. HC is cheaper where hot strength demands are lower; HH or HK austenitic castings carry higher loads. HD has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 98% of stainless steel grades. It melts at 1,370°C (2,498 °F). HD has a yield strength of 345 MPa (50 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 54% of stainless steel grades. Elongation at break is 16% and the elastic modulus is 195 GPa (28.3 Msi).
What is HD used for?
- radiant tube supports
- furnace fixtures
- heat treatment baskets
- high-temperature process equipment
Advantages
- High service temperature — 1,090°C (1,994 °F), better than 93% of stainless steel grades
- Low embodied carbon — 3.6 kg CO₂/kg, better than 83% of stainless steel grades
Limitations
- Limited formability — 5/100, worse than 99% of stainless steel grades
- Hard to polish — 45/100, worse than 96% of stainless steel grades
- Limited ductility — 16%, worse than 88% of stainless steel grades
- Difficult to machine — 25/100, worse than 88% of stainless steel grades
- Difficult to weld — 35/100, worse than 86% of stainless steel grades
HD properties
Typical room-temperature values for HD-F; bars are the position among stainless steel grades.
Physical3
HD has a density of 7.6 g/cm³ (0.275 lb/in³), lighter than 98% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical15
HD has a yield strength of 345 MPa (50 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 54% of stainless steel grades. Elongation at break is 16% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal5
HD is rated for continuous service to 1,090°C (1,994 °F). It conducts heat at 19 W/m·K (11 BTU/hr·ft·°F), better than 73% of stainless steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical3
HD conducts electricity at 2 % IACS, worse than 77% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is good (60/100), worse than 58% of stainless steel grades.
Sustainability4
Producing a kilogram of HD takes about 50 MJ of energy and emits 3.6 kg of CO₂ — less than 80% of stainless steel grades. Typical recycled content is 75%.
Manufacturability8
HD'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. 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. HD is highlighted; hover a dot for its name, or open the interactive family chart.
Working with HD
Is HD easy to machine?
Machine with rigid setups, positive-rake carbide, low speed and heavy feed to cut below the work-hardened skin; abrasive carbides give short tool life, so grinding is often preferred for finish surfaces.
Can HD be welded?
Weldable with E/ER 312 (29-9) or matching HD filler; preheat 150–260 °C, keep interpass moderate and slow-cool, then optionally solution anneal — as-cast and aged material is crack-sensitive.
Can HD be formed, bent or molded?
Sand or investment cast only; good fluidity but design generous fillets and avoid restrained sections because of the low hot ductility and high shrinkage of high-Cr alloys.
HD 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 |
|---|---|---|
| C0.50 % max per ASTM A297 | ≤ 0.5 | 0.4 |
| Mn | ≤ 1.5 | 1 |
| Sihigh Si aids scaling resistance | ≤ 2 | 1.5 |
| P | ≤ 0.04 | |
| S | ≤ 0.04 | |
| Cr | 26 – 30 | 28 |
| Ni | 4 – 7 | 5.5 |
| Moresidual, not intentionally added | ≤ 0.5 | |
| Fe | balance |
What surface finishes work on HD?
Normally supplied shot-blasted as-cast; passivate or leave the self-forming Cr₂O₃ scale — no anodizing, and plating adheres poorly to the cast skin.
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 HD in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- J93005
- ASTM
- A297 Grade HD
How much does HD cost?
HD is a premium-cost stainless steel ($$$), cheaper than about 51% 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.
HD — frequently asked
What is HD used for?
HD is typically used for radiant tube supports, furnace fixtures, heat treatment baskets and high-temperature process equipment. In short: stronger than Grade HC; 28Cr-5Ni heat-resisting casting; 1090 °C oxidizing service.
What is the yield strength of HD?
HD has a typical yield strength of 345 MPa (50 ksi) and a tensile strength of 585 MPa (84.8 ksi) — weaker than 54% of stainless steel grades. Strength varies by condition: see the 3 listed tempers.
Is HD easy to machine?
Not especially — machinability is rated poor (25/100, worse than 88% of stainless steel grades). Machine with rigid setups, positive-rake carbide, low speed and heavy feed to cut below the work-hardened skin; abrasive carbides give short tool life, so grinding is often preferred for finish surfaces.
Can HD be welded?
With care — weldability is rated fair (35/100). Weldable with E/ER 312 (29-9) or matching HD filler; preheat 150–260 °C, keep interpass moderate and slow-cool, then optionally solution anneal — as-cast and aged material is crack-sensitive.
What surface finishes work on HD?
Normally supplied shot-blasted as-cast; passivate or leave the self-forming Cr₂O₃ scale — no anodizing, and plating adheres poorly to the cast skin.
Can HD be formed, bent or molded?
Sand or investment cast only; good fluidity but design generous fillets and avoid restrained sections because of the low hot ductility and high shrinkage of high-Cr alloys.
What is the maximum service temperature of HD?
HD 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 HD-F and HD Aged?
F is the default condition — standard supply condition for all A297 HD castings; no heat treatment is required or normally applied. Aged: represents the embrittled condition after prolonged exposure in the 600–900 °C range; use these values for design checks on repair, handling and thermal-cycling loads. Yield strength is 345 MPa in F versus 415 MPa in Aged.
How much does HD cost?
HD is a premium-cost stainless steel ($$$), cheaper than about 51% 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)
- High Alloy Data Sheets, Heat Series (Grade HD) — Steel Founders' Society of America (SFSA) (2004)
- ASM Handbook Vol. 1: Properties and Selection — Irons, Steels, and High-Performance Alloys (Heat-Resistant Castings) — ASM International (1990)
- ASM Handbook Vol. 13B: Corrosion — Materials — ASM International (2005)
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.