Stainless Steel Alloy 28
UNS N08028 · ASTM B463/B668 · EN 1.4563, X1NiCrMoCu31-27-4 · also Sanicro 28, Nicrofer 3127hMo
Alloy 28 (N08028, 1.4563, X1NiCrMoCu31-27-4, also sold as Sanicro 28 and Nicrofer 3127hMo) is a high-nickel, high-molybdenum, copper-bearing superaustenitic alloy covered by ASTM B463/B668 and resistant to both oxidizing and reducing acids.
Reference datasheet — Alloy 28 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 SA condition
Alloy 28 tempers and conditions
Alloy 28 is supplied in 5 conditions, soft to hard. SA is the default FabDigit quotes; the values on this page are for it.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Hot Finished / Hot Rolled + solution annealed bar and plate | Specify for large-section bar and heavy plate delivered hot rolled and solution annealed; properties are close to the solution treated state but the surface is mill scale or pickled. | 250 | 600 | 45 | 175 HB | 1.7 % IACS |
SADefault Solution Annealed | Pick as the standard supply condition for plate, tube and bar solution annealed at 1100–1180 °C and water quenched, giving the best corrosion resistance at 260 MPa yield and 45 % elongation. | 260 | 620 | 45 | 170 HB | — |
As-welded deposit | Use these values for weld joints left without post-weld solution treatment; overalloyed Ni-base filler offsets segregation, giving 320 MPa yield but corrosion resistance below the annealed base. | 320 | 600 | 32 | 180 HB | 1.7 % IACS |
Cold drawn | Choose for bar and seamless tube needing higher yield (520 MPa) and tighter dimensional accuracy after annealing plus a light draw, accepting 28 % elongation and reduced formability. | 520 | 750 | 28 | 21 HRC | 1.7 % IACS |
High-strength cold worked tube | Use heavily drawn thin-wall tube with no final anneal for subsea umbilicals and high-pressure lines at 750 MPa yield, accepting 15 % elongation and very limited further forming. | 750 | 900 | 15 | 30 HRC | 1.7 % IACS |
What is Alloy 28?
Alloy 28 (N08028, 1.4563, X1NiCrMoCu31-27-4, also sold as Sanicro 28 and Nicrofer 3127hMo) is a high-nickel, high-molybdenum, copper-bearing superaustenitic alloy covered by ASTM B463/B668 and resistant to both oxidizing and reducing acids. It is specified for phosphoric and sulfuric acid duty and supplied as solution-annealed plate and tube, cold-drawn tube, hot-worked/cold-worked and hot-finished bar and as-welded pipe, with 260 MPa yield, 620 MPa tensile, 45 % elongation and 170 HB. Service is limited to about 500 °C and machinability is low (score 28). For chloride pitting rather than acid service, a 6Mo grade such as S31254 is the closer choice. Alloy 28 has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,350°C (2,462 °F). Alloy 28 has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
What is Alloy 28 used for?
- phosphoric acid production
- flue gas desulfurization
- oil and gas tubulars
- chemical process equipment
Advantages
- Good corrosion resistance — 82/100, better than 90% of stainless steel grades
- Ductile — tolerates forming and impact — 45%, better than 76% of stainless steel grades
Limitations
- High embodied carbon — 8 kg CO₂/kg, worse than 99% of stainless steel grades
- Poor heat conductor — 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades
- Low electrical conductivity — 1.7 % IACS, worse than 93% of stainless steel grades
- Low strength — 260 MPa (37.7 ksi), worse than 84% of stainless steel grades
Alloy 28 properties
Typical room-temperature values for Alloy 28-SA; bars are the position among stainless steel grades.
Physical3
Alloy 28 has a density of 8 g/cm³ (0.289 lb/in³), heavier than 92% of stainless steel grades. It melts at 1,350°C (2,462 °F).
Mechanical14
Alloy 28 has a yield strength of 260 MPa (37.7 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 84% of stainless steel grades. Elongation at break is 45% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
Alloy 28 is rated for continuous service to 500°C (932 °F). It conducts heat at 11.5 W/m·K (6.64 BTU/hr·ft·°F), worse than 97% of stainless steel grades. Thermal expansion is 14.5 µm/m·K (8.06 µin/in·°F).
Electrical3
Alloy 28 conducts electricity at 1.7 % IACS, worse than 93% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (82/100), better than 90% of stainless steel grades.
Sustainability4
Producing a kilogram of Alloy 28 takes about 105 MJ of energy and emits 8 kg of CO₂ — more than 99% of stainless steel grades. Typical recycled content is 40%.
Manufacturability6
Alloy 28's machinability is poor (28/100, worse than 79% of stainless steel grades); weldability very good (70/100); formability good (65/100).
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. Alloy 28 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Alloy 28
Is Alloy 28 easy to machine?
Work hardens sharply and conducts heat poorly: use rigid clamping, sharp positive-rake tooling, low speed with heavy feed and keep the cut continuous. Supply high-volume emulsion coolant or high-pressure through-tool coolant.
Can Alloy 28 be welded?
GTAW, GMAW and SMAW are all suitable; use over-alloyed nickel-base filler (ERNiCrMo-3 / Alloy 625 type) to compensate for molybdenum segregation. Keep heat input low and interpass temperature ≤150 °C; no preheat and no slow-cooled post-weld stress relief.
Can Alloy 28 be formed, bent or molded?
Cold formability is good, but springback and work hardening are pronounced, so allow higher forming forces and plan intermediate solution annealing. Hot work at about 1150–900 °C, followed by mandatory water-quench solution treatment.
Alloy 28 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 |
|---|---|---|
| Clow carbon for intergranular corrosion resistance | ≤ 0.03 | 0.02 |
| Si | ≤ 1 | 0.5 |
| Mn | ≤ 2.5 | 1.5 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Cr | 26 – 28 | 27 |
| Ni | 29.5 – 32.5 | 31 |
| Mo | 3 – 4 | 3.5 |
| Cukey for sulfuric/phosphoric acid resistance | 0.6 – 1.4 | 1 |
| Febalance, approx. 35% | balance |
What surface finishes work on Alloy 28?
Pickle and passivate in HNO₃-HF to restore the passive film after welding and hot work. The alloy can be mechanically polished to a mirror finish and needs no plating; do not leave iron contamination on the surface.
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 Alloy 28 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does Alloy 28 cost?
Alloy 28 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.
Alloy 28 — frequently asked
What is Alloy 28 used for?
Alloy 28 is typically used for phosphoric acid production, flue gas desulfurization, oil and gas tubulars and chemical process equipment. In short: phosphoric acid workhorse; high-Mo, copper-bearing austenitic; wet corrosion, not high heat.
What is the yield strength of Alloy 28?
Alloy 28 has a typical yield strength of 260 MPa (37.7 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 84% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is Alloy 28 easy to machine?
Not especially — machinability is rated poor (28/100, worse than 79% of stainless steel grades). Work hardens sharply and conducts heat poorly: use rigid clamping, sharp positive-rake tooling, low speed with heavy feed and keep the cut continuous. Supply high-volume emulsion coolant or high-pressure through-tool coolant.
Can Alloy 28 be welded?
Yes — weldability is rated very good (70/100). GTAW, GMAW and SMAW are all suitable; use over-alloyed nickel-base filler (ERNiCrMo-3 / Alloy 625 type) to compensate for molybdenum segregation. Keep heat input low and interpass temperature ≤150 °C; no preheat and no slow-cooled post-weld stress relief.
What surface finishes work on Alloy 28?
Pickle and passivate in HNO₃-HF to restore the passive film after welding and hot work. The alloy can be mechanically polished to a mirror finish and needs no plating; do not leave iron contamination on the surface.
Can Alloy 28 be formed, bent or molded?
Cold formability is good, but springback and work hardening are pronounced, so allow higher forming forces and plan intermediate solution annealing. Hot work at about 1150–900 °C, followed by mandatory water-quench solution treatment.
What is the maximum service temperature of Alloy 28?
Alloy 28 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between Alloy 28-SA and Alloy 28 HW-CW?
SA is the default condition — pick as the standard supply condition for plate, tube and bar solution annealed at 1100–1180 °C and water quenched, giving the best corrosion resistance at 260 MPa yield and 45 % elongation. HW-CW: use heavily drawn thin-wall tube with no final anneal for subsea umbilicals and high-pressure lines at 750 MPa yield, accepting 15 % elongation and very limited further forming. Yield strength is 260 MPa in SA versus 750 MPa in HW-CW.
How much does Alloy 28 cost?
Alloy 28 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 B668 — UNS N08028 Seamless Tube — ASTM International (2019)
- ASTM B709 — UNS N08028 Plate, Sheet and Strip — ASTM International (2018)
- EN 10088-2 / X1NiCrMoCu31-27-4 (1.4563) — CEN (2014)
- Sanicro 28 alloy datasheet — Alleima (formerly Sandvik Materials Technology) (2023)
- Nicrofer 3127 hMo — Alloy 28 material data sheet — VDM Metals (2020)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
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.