Stainless Steel Alloy 20 · temper · default condition
Stainless Steel Alloy 20 Annealed
Properties of the Annealed condition, compared with the other Alloy 20 tempers.
Default stock condition for plate, sheet, bar, pipe and fittings in acid-service equipment.
What is Alloy 20 Annealed?
Alloy 20 Annealed is Alloy 20 in the Annealed temper — default stock condition for plate, sheet, bar, pipe and fittings in acid-service equipment. Alloy 20 Annealed has a yield strength of 310 MPa (45 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 40% and the elastic modulus is 193 GPa (28 Msi). Alloy 20 Annealed has a density of 8.08 g/cm³ (0.292 lb/in³), heavier than 99% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Advantages
- Good corrosion resistance — 80/100, better than 88% of stainless steel grades
- Forms and bends easily — 72/100, better than 83% of stainless steel grades
- Readily welded — 80/100, better than 79% of stainless steel grades
Limitations
- Low electrical conductivity — 1.6 % IACS, worse than 99% of stainless steel grades
- High embodied carbon — 7.5 kg CO₂/kg, worse than 97% of stainless steel grades
- Poor heat conductor — 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 92% of stainless steel grades
Alloy 20 Annealed properties
Typical room-temperature values for Alloy 20 Annealed — 14 properties are specific to this condition; the rest are grade-level values shared by every Alloy 20 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
Alloy 20 Annealed has a density of 8.08 g/cm³ (0.292 lb/in³), heavier than 99% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical13
Alloy 20 Annealed has a yield strength of 310 MPa (45 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 63% of stainless steel grades. Elongation at break is 40% and the elastic modulus is 193 GPa (28 Msi).
Thermal6
Alloy 20 Annealed is rated for continuous service to 500°C (932 °F). It conducts heat at 12 W/m·K (6.93 BTU/hr·ft·°F), worse than 92% of stainless steel grades. Thermal expansion is 14.8 µm/m·K (8.22 µin/in·°F).
Electrical3
Alloy 20 Annealed conducts electricity at 1.6 % IACS, worse than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 88% of stainless steel grades.
Sustainability4
Producing a kilogram of Alloy 20 Annealed takes about 100 MJ of energy and emits 7.5 kg of CO₂ — more than 98% of stainless steel grades. Typical recycled content is 45%.
Manufacturability8
Alloy 20 Annealed's machinability is fair (38/100, better than 63% of stainless steel grades); weldability very good (80/100); formability very good (72/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other Alloy 20 tempers and conditions
Alloy 20 is also supplied in 4 other conditions. The full side-by-side table is on the Alloy 20 overview.
- AnnealedDefaultDefault stock condition for plate, sheet, bar, pipe and fittings in acid-service equipment.310 MPa yield · 160 HB
- Cold Worked HardMaximum strength condition for springs, fasteners and thin-wall tubing; ductility and formability are much reduced.790 MPa yield · 32 HRC
- Cold DrawnHigher strength and better surface/tolerance for machined shafts, fasteners and pump parts.620 MPa yield · 24 HRC
- Hot FinishedChoose for heavy sections, forgings and large-diameter seamless pipe where scale/tolerance is acceptable.300 MPa yield · 170 HB
- Solution AnnealedFull solution treatment for maximum corrosion resistance after heavy cold work or fabrication welding.290 MPa yield · 155 HB
Working with Alloy 20 Annealed
Is Alloy 20 easy to machine?
Machines like a tough austenitic: rigid setups, positive-rake sharp carbide, heavy constant feed, low-to-moderate speed and flood coolant to avoid work-hardened glazing; rating ≈ 40% of B1112.
Can Alloy 20 be welded?
Readily welded by GTAW/GMAW/SMAW with matching 20Cb-3 or ENiCrMo-3/ERNiCrMo-3 filler; keep heat input and interpass temperature low, no preheat, PWHT normally unnecessary thanks to Nb stabilization.
Can Alloy 20 be formed, bent or molded?
Good cold formability with high work-hardening — allow extra springback and interstage annealing at 925–1010 °C; hot work at 1040–1180 °C and quench after forming.
What surface finishes work on Alloy 20?
Pickle (HNO3-HF) and passivate per ASTM A967 after hot work or welding; electropolishing gives the smoothest acid-service surface; not anodizable, plating rarely used.
Alloy 20 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 |
|---|---|---|
| Niprimary austenite stabilizer, SCC resistance | 32 – 38 | 34 |
| Cr | 19 – 21 | 20 |
| Cukey for sulfuric acid resistance | 3 – 4 | 3.5 |
| Mo | 2 – 3 | 2.5 |
| NbCb (+Ta) ≥ 8×C; stabilization against sensitization | ≤ 1 | 0.5 |
| C | ≤ 0.07 | 0.03 |
| Mn | ≤ 2 | 0.6 |
| Si | ≤ 1 | 0.4 |
| P | ≤ 0.05 | — |
| S | ≤ 0.04 | — |
| Febalance, approx. 35% | balance | — |
Alloy 20 Annealed — frequently asked
What is Alloy 20 Annealed used for?
Alloy 20 Annealed is typically used for sulfuric acid tanks and vessels, chemical process pumps and impellers, valve bodies for acid service, heat exchanger tubing and tubesheets, pickling line fixtures and racks and mixing tank agitators and shafts. In short: best chemical resistance.
What is the yield strength of Alloy 20 Annealed?
Alloy 20 Annealed has a typical yield strength of 310 MPa (45 ksi) and a tensile strength of 620 MPa (89.9 ksi) — weaker than 63% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is Alloy 20 Annealed easy to machine?
Not especially — machinability is rated fair (38/100, better than 63% of stainless steel grades). Machines like a tough austenitic: rigid setups, positive-rake sharp carbide, heavy constant feed, low-to-moderate speed and flood coolant to avoid work-hardened glazing; rating ≈ 40% of B1112.
Can Alloy 20 Annealed be welded?
Yes — weldability is rated very good (80/100). Readily welded by GTAW/GMAW/SMAW with matching 20Cb-3 or ENiCrMo-3/ERNiCrMo-3 filler; keep heat input and interpass temperature low, no preheat, PWHT normally unnecessary thanks to Nb stabilization.
What surface finishes work on Alloy 20 Annealed?
Pickle (HNO3-HF) and passivate per ASTM A967 after hot work or welding; electropolishing gives the smoothest acid-service surface; not anodizable, plating rarely used.
Can Alloy 20 Annealed be formed, bent or molded?
Good cold formability with high work-hardening — allow extra springback and interstage annealing at 925–1010 °C; hot work at 1040–1180 °C and quench after forming.
What is the maximum service temperature of Alloy 20 Annealed?
Alloy 20 Annealed 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.
Can FabDigit make parts in Alloy 20 Annealed?
Yes — Alloy 20 Annealed is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM B463 — UNS N08020 Plate, Sheet and Strip — ASTM International (2020)
- ASTM B473 — UNS N08020 Bar and Wire — ASTM International (2020)
- ASTM B464/B729 — UNS N08020 Welded and Seamless Pipe/Tube — ASTM International (2020)
- Carpenter 20Cb-3 Stainless Alloy Technical Datasheet — Carpenter Technology (2020)
- Alloy 20 (N08020) Data Sheet — Rolled Alloys / Sandmeyer Steel (2021)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
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.