Steel A372 Grade D
ASTM A372 Grade D
A372 Grade D is the highest-strength of the basic carbon grades in ASTM A372, quenched and tempered to give maximum allowable stress in thin-walled pressure vessel forgings.
Reference datasheet — A372 Grade D 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 QT condition
A372 Grade D tempers and conditions
A372 Grade D is supplied in 3 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 3 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition, used for rough machining or deep boring of shells before final Q&T of the finished forging. | 310 | 570 | 23 | 6 HRC | 10 % IACS |
Normalized | Grain-refined pre-heat-treat condition of rough forgings before the final quench and temper; not acceptable as final Grade D delivery state. | 350 | 640 | 20 | 11 HRC | 9.8 % IACS |
QTDefault Quenched and tempered | The standard delivery condition for Grade D forgings; use when full specified 690/515 MPa pressure-vessel properties are required. | 550 | 725 | 18 | 20 HRC | — |
What is A372 Grade D?
A372 Grade D is the highest-strength of the basic carbon grades in ASTM A372, quenched and tempered to give maximum allowable stress in thin-walled pressure vessel forgings. Typical properties are 550 MPa yield, 725 MPa tensile, 18 % elongation, 215 HB and 20 HRC, with normalized and annealed conditions also on file for machining and forming stages. Ductility and cold formability are the lowest in the group, service is limited to 400 °C, and the carbon equivalent near 0.6 means preheat and PWHT are mandatory; welding after quench-and-temper requires requalification. Choose Grade C where fabrication ease outweighs the extra strength. A372 Grade D 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 D has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 71% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
What is A372 Grade D used for?
- High-pressure gas cylinders
- Rocket motor cases
- Pressure vessel forgings requiring max strength
Advantages
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
A372 Grade D properties
Typical room-temperature values for A372 Grade D-QT; bars are the position among steel grades.
Physical3
A372 Grade D 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).
Mechanical17
A372 Grade D has a yield strength of 550 MPa (79.8 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 71% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A372 Grade D is rated for continuous service to 400°C (752 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
A372 Grade D conducts electricity at 9.5 % IACS, better than 75% 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 D takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
A372 Grade D's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (40/100); formability poor (25/100).
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 D is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A372 Grade D
Is A372 Grade D easy to machine?
Machine in the annealed or normalized state where possible; at 200–250 HB use rigid setups, carbide inserts at ~120–180 m/min and generous coolant to control work hardening on bores.
Can A372 Grade D be welded?
Weldable with low-hydrogen consumables but the ~0.6 carbon equivalent demands 150–260 °C preheat and PWHT; any welding after quench-and-temper needs re-qualification of properties.
Can A372 Grade D be formed, bent or molded?
Shaped by hot forging/back-extrusion of thin-walled shells at 1100–1200 °C; cold forming of the Q&T material is essentially limited to light straightening.
A372 Grade D 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 |
|---|---|---|
| Cmedium-carbon; heat analysis per ASTM A372 carbon grades | 0.35 – 0.5 | 0.45 |
| Mn | 0.6 – 1.1 | 0.85 |
| Sikilled steel | 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 D?
No corrosion resistance of its own — shot blast then paint, zinc-rich primer, phosphate-and-oil or plating; keep plating baths and pickling controlled to avoid hydrogen embrittlement and bake after plating.
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 D cost?
A372 Grade D is a standard-cost steel ($$), cheaper than about 71% 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 D — frequently asked
What is A372 Grade D used for?
A372 Grade D is typically used for high-pressure gas cylinders, rocket motor cases and pressure vessel forgings requiring max strength. In short: strongest basic A372 carbon grade; Q&T high-pressure forging steel; lowest-ductility A372 grade.
What is the yield strength of A372 Grade D?
A372 Grade D has a typical yield strength of 550 MPa (79.8 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 71% of steel grades. Strength varies by condition: see the 3 listed tempers.
Is A372 Grade D easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the annealed or normalized state where possible; at 200–250 HB use rigid setups, carbide inserts at ~120–180 m/min and generous coolant to control work hardening on bores.
Can A372 Grade D be welded?
With care — weldability is rated fair (40/100). Weldable with low-hydrogen consumables but the ~0.6 carbon equivalent demands 150–260 °C preheat and PWHT; any welding after quench-and-temper needs re-qualification of properties.
What surface finishes work on A372 Grade D?
No corrosion resistance of its own — shot blast then paint, zinc-rich primer, phosphate-and-oil or plating; keep plating baths and pickling controlled to avoid hydrogen embrittlement and bake after plating.
Can A372 Grade D be formed, bent or molded?
Shaped by hot forging/back-extrusion of thin-walled shells at 1100–1200 °C; cold forming of the Q&T material is essentially limited to light straightening.
What is the maximum service temperature of A372 Grade D?
A372 Grade D is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between A372 Grade D-QT and A372 Grade D-A?
QT is the default condition — the standard delivery condition for Grade D forgings; use when full specified 690/515 MPa pressure-vessel properties are required. A: softest condition, used for rough machining or deep boring of shells before final Q&T of the finished forging. Yield strength is 550 MPa in QT versus 310 MPa in A.
How much does A372 Grade D cost?
A372 Grade D is a standard-cost steel ($$), cheaper than about 71% 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)
- 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)
- ASTM A370 — Mechanical Testing of Steel Products (hardness conversion tables) — ASTM International (2022)
- ASME BPVC Section II Part D / Section VIII Div. 1 — ASME (2023)
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.