Steel A372 Grade A
ASTM A372 Grade A
A372 Grade A is the lowest-strength carbon steel forging grade of the ASTM A372 series, used for thin-walled pressure vessels such as gas cylinders where moderate strength is sufficient.
Reference datasheet — A372 Grade A 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 N condition
A372 Grade A tempers and conditions
A372 Grade A is supplied in 5 conditions, soft to hard. N 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 |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition for heavy machining, deep cold forming or re-forging; strength may fall below the A372 spec minima until re-normalized. | 250 | 460 | 32 | 130 HB | — |
As-forged | Intermediate mill condition only — properties are non-uniform and A372 requires subsequent normalizing or Q&T before acceptance. | 290 | 520 | 22 | 160 HB | 10 % IACS |
Normalized and tempered | Pick when residual stresses and hardness scatter must be tightened (e.g. NACE hardness cap, machining stability). | 295 | 510 | 28 | 148 HB | 10 % IACS |
NDefault Normalized | Standard supply condition for A372 Grade A thin-walled cylinder forgings; uniform fine grain, meets 485/248 MPa minima. | 300 | 530 | 26 | 155 HB | — |
Quenched and tempered | Optional for thin sections where higher yield and better toughness than normalized are wanted while keeping Grade A chemistry. | 420 | 600 | 23 | 185 HB | 9.5 % IACS |
What is A372 Grade A?
A372 Grade A is the lowest-strength carbon steel forging grade of the ASTM A372 series, used for thin-walled pressure vessels such as gas cylinders where moderate strength is sufficient. Typical properties are 300 MPa yield, 530 MPa tensile, 26 % elongation and 155 HB (82 HRB), with conditions on file covering normalized, normalized-and-tempered, annealed, quenched-and-tempered and as-forged. Weldability is good for the family (score 75), but service is limited to 425 °C and the steel rusts quickly without a coating. A372 Grade B or C gives higher allowable stress in the same forging route. A372 Grade A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). A372 Grade A has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 86% of steel grades. Elongation at break is 26% and the elastic modulus is 200 GPa (29 Msi).
What is A372 Grade A used for?
- Gas cylinders
- Thin-wall pressure vessel forgings
- Accumulator shells
Advantages
- Easy to machine — 62/100, better than 89% of steel grades
- Conducts heat well — 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades
- High electrical conductivity — 10 % IACS, better than 83% of steel grades
- Ductile — tolerates forming and impact — 26%, better than 82% of steel grades
- Readily welded — 75/100, better than 76% of steel grades
Limitations
- Low strength — 300 MPa (43.5 ksi), worse than 86% of steel grades
A372 Grade A properties
Typical room-temperature values for A372 Grade A-N; bars are the position among steel grades.
Physical3
A372 Grade A has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
A372 Grade A has a yield strength of 300 MPa (43.5 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 86% of steel grades. Elongation at break is 26% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
A372 Grade A is rated for continuous service to 425°C (797 °F). It conducts heat at 50 W/m·K (28.9 BTU/hr·ft·°F), better than 87% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
A372 Grade A conducts electricity at 10 % IACS, better than 83% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of A372 Grade A takes about 26 MJ of energy and emits 2 kg of CO₂ — less than 64% of steel grades. Typical recycled content is 30%.
Manufacturability8
A372 Grade A's machinability is good (62/100, better than 89% of steel grades); weldability very good (75/100); formability good (60/100).
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 steel family
Yield strength against density for every steel grade FabDigit runs. A372 Grade A is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A372 Grade A
Is A372 Grade A easy to machine?
Machines like normalized 1030–1035: ~60 % of 1212, carbide inserts at 150–200 m/min, good chip control in the normalized state.
Can A372 Grade A be welded?
Readily welded by SMAW/GMAW/SAW with E70-class consumables; CE ≈0.45 so preheat 100–150 °C for sections over ~25 mm and PWHT per ASME as required.
Can A372 Grade A be formed, bent or molded?
Hot forged 1100–1250 °C then normalized; cold expansion/necking of thin cylinder walls is feasible in the annealed or normalized state with generous bend radii.
A372 Grade A 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 |
|---|---|---|
| Ccarbon-steel Grade A | ≤ 0.35 | 0.3 |
| Mn | 0.6 – 0.9 | 0.75 |
| Si | 0.15 – 0.35 | 0.25 |
| P | ≤ 0.03 | 0.02 |
| S | ≤ 0.03 | 0.02 |
| Fe | balance |
What surface finishes work on A372 Grade A?
No anodizing — protect with shot blast + zinc/epoxy paint, phosphate or electroless nickel; bare surfaces flash-rust within hours in humid air.
Surface treatments FabDigit runs on 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).
Organic Coating
Black / Phosphate
Thermal Spray
How much does A372 Grade A cost?
A372 Grade A is a budget-cost steel ($), cheaper than about 90% 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.
A372 Grade A — frequently asked
What is A372 Grade A used for?
A372 Grade A is typically used for gas cylinders, thin-wall pressure vessel forgings and accumulator shells. In short: most weldable A372 grade; lowest-strength A372 forging; easiest-forming cylinder steel.
What is the yield strength of A372 Grade A?
A372 Grade A has a typical yield strength of 300 MPa (43.5 ksi) and a tensile strength of 530 MPa (76.9 ksi) — weaker than 86% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A372 Grade A easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machines like normalized 1030–1035: ~60 % of 1212, carbide inserts at 150–200 m/min, good chip control in the normalized state.
Can A372 Grade A be welded?
Yes — weldability is rated very good (75/100). Readily welded by SMAW/GMAW/SAW with E70-class consumables; CE ≈0.45 so preheat 100–150 °C for sections over ~25 mm and PWHT per ASME as required.
What surface finishes work on A372 Grade A?
No anodizing — protect with shot blast + zinc/epoxy paint, phosphate or electroless nickel; bare surfaces flash-rust within hours in humid air.
Can A372 Grade A be formed, bent or molded?
Hot forged 1100–1250 °C then normalized; cold expansion/necking of thin cylinder walls is feasible in the annealed or normalized state with generous bend radii.
What is the maximum service temperature of A372 Grade A?
A372 Grade A is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A372 Grade A-N and A372 Grade A-QT?
N is the default condition — standard supply condition for A372 Grade A thin-walled cylinder forgings; uniform fine grain, meets 485/248 MPa minima. QT: optional for thin sections where higher yield and better toughness than normalized are wanted while keeping Grade A chemistry. Yield strength is 300 MPa in N versus 420 MPa in QT.
How much does A372 Grade A cost?
A372 Grade A is a budget-cost steel ($), cheaper than about 90% 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 A372/A372M — Carbon and Alloy Steel Forgings for Thin-Walled Pressure Vessels — ASTM International (2020)
- ASME BPVC Section II Part D — Material Properties — ASME (2023)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASTM A370 — Mechanical Testing of Steel Products (hardness conversions) — ASTM International (2022)
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.