Steel A203-SR (Stress relieved)
Heat-treated state
ASTM A203 · UNS K21590
Condition after 595–635 °C post-weld heat treatment of formed heads and welded shells; slightly lower yield, restored toughness.
Values for the SR condition
Other A203 tempers and conditions
A203 is listed in 6 conditions; see the grade overview at A203.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Grade A | Lowest-strength 2.25%Ni plate for vessels down to about −59 °C where weight is not critical. | 290 | 490 | 28 | 140 HB | 40 W/m·K |
Grade D | Standard 3.5%Ni plate for cryogenic vessels and piping down to about −101 °C at moderate design stress. | 295 | 490 | 28 | 143 HB | 35 W/m·K |
Grade B | Choose when 2.25%Ni toughness is enough but a 70–90 ksi tensile class is needed to cut wall thickness. | 320 | 530 | 25 | 152 HB | 39 W/m·K |
GR-E-NDefault Grade E | Most commonly stocked A203 plate: 3.5%Ni toughness to −101 °C with the higher 70–90 ksi tensile class. | 325 | 535 | 25 | 156 HB | 35 W/m·K |
SRThis page Stress relieved | Condition after 595–635 °C post-weld heat treatment of formed heads and welded shells; slightly lower yield, restored toughness. | 335 | 520 | 28 | 152 HB | 7.5 % IACS |
Grade F | Pick when the highest A203 design stress (55 ksi yield) is needed together with −101 °C toughness; Q&T supply only. | 630 | 745 | 22 | 21 HRC | 35 W/m·K |
What is A203-SR?
A203-SR is A203 heat treated to SR — condition after 595–635 °C post-weld heat treatment of formed heads and welded shells; slightly lower yield, restored toughness. A203-SR has a yield strength of 335 MPa (48.6 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of steel grades. Elongation at break is 28% and the elastic modulus is 205 GPa (29.7 Msi). A203-SR has a density of 7.87 g/cm³ (0.284 lb/in³), heavier than 92% of steel grades. It melts at 1,415°C (2,579 °F). GR-E-N is the default condition FabDigit quotes; SR is available on request or by drawing note.
Advantages
- Tough — resists crack growth — 160 MPa·√m (145.6 ksi·√in), better than 98% of steel grades
- Ductile — tolerates forming and impact — 28%, better than 89% of steel grades
- Forms and bends easily — 68/100, better than 83% of steel grades
- Readily welded — 72/100, better than 75% of steel grades
Limitations
- High embodied carbon — 2.7 kg CO₂/kg, worse than 89% of steel grades
- Low strength — 335 MPa (48.6 ksi), worse than 77% of steel grades
A203-SR properties
Typical room-temperature values for A203-SR; 23 are specific to this condition. Other listed values are A203 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
A203-SR has a density of 7.87 g/cm³ (0.284 lb/in³), heavier than 92% of steel grades. It melts at 1,415°C (2,579 °F).
Mechanical16
A203-SR has a yield strength of 335 MPa (48.6 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of steel grades. Elongation at break is 28% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A203-SR is rated for continuous service to 340°C (644 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 11.2 µm/m·K (6.22 µin/in·°F).
Electrical3
A203-SR conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of A203-SR takes about 36 MJ of energy and emits 2.7 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 28%.
Manufacturability7
A203-SR's machinability is good (58/100, better than 75% of steel grades); weldability very good (72/100); formability good (68/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with A203-SR
Is A203 easy to machine?
Machines like a 160–190 HB low-alloy steel — use rigid setups, sharp positive-rake carbide and generous coolant; the nickel makes chips gummier than plain carbon plate so run moderate speed with heavier feed.
Can A203 be welded?
Readily welded by SMAW/SAW/GTAW with matching 2.5Ni or 3.5Ni low-hydrogen consumables; preheat 100–150 °C for thick sections, control interpass and heat input, and PWHT at 595–635 °C where the code requires it, verifying weld-metal CVN at the design temperature.
Can A203 be formed, bent or molded?
Hot form above 900 °C then re-normalize, or cold roll/press heads with generous bend radii (≥2t) and re-heat-treat if cold strain exceeds 5 % to restore low-temperature toughness.
What surface finishes work on A203?
No anodizing possible; blast to SA 2.5 and apply epoxy/zinc-rich paint, metallizing or cladding for wet and marine service — the base steel corrodes like ordinary carbon steel.
A203 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 |
|---|---|---|
| CGrade A/D ≤0.17, Grade B ≤0.21, Grade E/F ≤0.20 (heat analysis; limits rise slightly with thickness) | ≤ 0.2 | 0.17 |
| Mn0.80 max for Grade F and for heavier plate | ≤ 0.7 | 0.6 |
| P | ≤ 0.03 | 0.01 |
| S | ≤ 0.03 | 0.01 |
| Si | 0.15 – 0.4 | 0.28 |
| NiGrades D/E/F; Grades A/B are 2.10–2.50 % Ni | 3.25 – 3.75 | 3.5 |
| Fe | balance | — |
A203-SR — frequently asked
What is A203-SR used for?
A203-SR is typically used for cryogenic pressure vessels, LNG/LPG storage tanks, low-temperature piping heads and refrigeration equipment. In short: nickel plate for cryogenic vessels; tougher than carbon steel plate; weldable with matching Ni consumables.
What is the yield strength of A203-SR?
A203-SR has a typical yield strength of 335 MPa (48.6 ksi) and a tensile strength of 520 MPa (75.4 ksi) — weaker than 77% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is A203-SR easy to machine?
Reasonably — machinability is rated good (58/100, better than 75% of steel grades). Machines like a 160–190 HB low-alloy steel — use rigid setups, sharp positive-rake carbide and generous coolant; the nickel makes chips gummier than plain carbon plate so run moderate speed with heavier feed.
Can A203-SR be welded?
Yes — weldability is rated very good (72/100). Readily welded by SMAW/SAW/GTAW with matching 2.5Ni or 3.5Ni low-hydrogen consumables; preheat 100–150 °C for thick sections, control interpass and heat input, and PWHT at 595–635 °C where the code requires it, verifying weld-metal CVN at the design temperature.
What surface finishes work on A203-SR?
No anodizing possible; blast to SA 2.5 and apply epoxy/zinc-rich paint, metallizing or cladding for wet and marine service — the base steel corrodes like ordinary carbon steel.
Can A203-SR be formed, bent or molded?
Hot form above 900 °C then re-normalize, or cold roll/press heads with generous bend radii (≥2t) and re-heat-treat if cold strain exceeds 5 % to restore low-temperature toughness.
What is the maximum service temperature of A203-SR?
A203-SR is rated for continuous use to about 340°C (644 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A203 GR-E-N and A203 GR-F-QT?
GR-E-N is the default condition — most commonly stocked A203 plate: 3.5%Ni toughness to −101 °C with the higher 70–90 ksi tensile class. GR-F-QT: pick when the highest A203 design stress (55 ksi yield) is needed together with −101 °C toughness; Q&T supply only. Yield strength is 325 MPa in GR-E-N versus 630 MPa in GR-F-QT.
Sources
- ASTM A203/A203M — Pressure Vessel Plates, Alloy Steel, Nickel — ASTM International (2022)
- ASME BPVC Section II Part A / Part D — SA-203 material and allowable stresses — ASME (2023)
- ASME BPVC Section VIII Div.1 UCS/UHA impact-test requirements — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- Low-temperature nickel steel plate datasheets (2.25Ni / 3.5Ni pressure-vessel plate) — Dillinger / NSSMC / Baosteel (2022)
- GB/T 3531 (comparison grades 09MnNiDR / 3.5Ni) — SAC (2014)
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.