Stainless Steel Alloy 28-AW (As-welded deposit)
Heat-treated state
UNS N08028 · ASTM B463/B668 · EN 1.4563, X1NiCrMoCu31-27-4 · also Sanicro 28, Nicrofer 3127hMo
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.
Values for the AW condition
Other Alloy 28 tempers and conditions
Alloy 28 is listed in 5 conditions; see the grade overview at Alloy 28.
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 | — |
AWThis page 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-AW?
Alloy 28-AW is Alloy 28 heat treated to AW — 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. Alloy 28-AW has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 60% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 195 GPa (28.3 Msi). Alloy 28-AW 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). SA is the default condition FabDigit quotes; AW is available on request or by drawing note.
Advantages
- Good corrosion resistance — 76/100, better than 80% 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
Alloy 28-AW properties
Typical room-temperature values for Alloy 28-AW; 22 are specific to this condition. Other listed values are Alloy 28 reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
Alloy 28-AW 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-AW has a yield strength of 320 MPa (46.4 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 60% of stainless steel grades. Elongation at break is 32% and the elastic modulus is 195 GPa (28.3 Msi).
Thermal6
Alloy 28-AW 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-AW conducts electricity at 1.7 % IACS, worse than 93% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (76/100), better than 80% of stainless steel grades.
Sustainability4
Producing a kilogram of Alloy 28-AW 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-AW's machinability is poor (26/100, worse than 84% of stainless steel grades); weldability very good (70/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with Alloy 28-AW
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.
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.
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 | — |
Alloy 28-AW — frequently asked
What is Alloy 28-AW used for?
Alloy 28-AW 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-AW?
Alloy 28-AW has a typical yield strength of 320 MPa (46.4 ksi) and a tensile strength of 600 MPa (87 ksi) — weaker than 60% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is Alloy 28-AW easy to machine?
Not especially — machinability is rated poor (26/100, worse than 84% 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-AW 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-AW?
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-AW 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-AW?
Alloy 28-AW 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.