Steel A372 Gr E
ASTM A372 Gr E
A372 Grade E is a high-strength quenched-and-tempered forged and bored alloy steel, typically Cr-Mo-V, used for thick-wall pressure vessel components; the specification covers Class 55, 65 and 70 strength levels.
Reference datasheet — A372 Gr E 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 CL70-QT condition
A372 Gr E tempers and conditions
A372 Gr E is supplied in 5 conditions, soft to hard. CL70-QT 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 | Soft intermediate condition supplied for rough boring/machining before final quench and temper — not a certified A372 delivery class. | 370 | 590 | 26 | 170 HB | — |
Normalized and tempered | Used where section size prevents effective liquid quenching; gives Class 55-level properties with more uniform through-thickness structure. | 415 | 640 | 23 | 12 HRC | 8 % IACS |
Class 55 | Lowest strength class — pick for thicker walls, best toughness and easiest machining/welding. | 420 | 630 | 24 | 187 HB | — |
Class 65 | Intermediate strength/toughness balance for medium-wall cylinders and rings. | 485 | 700 | 22 | 18 HRC | — |
CL70-QTDefault Class 70 | Most commonly ordered class — highest strength of Grade E for thin-wall, high-pressure gas cylinders and accumulators. | 515 | 725 | 20 | 20 HRC | — |
What is A372 Gr E?
A372 Grade E is a high-strength quenched-and-tempered forged and bored alloy steel, typically Cr-Mo-V, used for thick-wall pressure vessel components; the specification covers Class 55, 65 and 70 strength levels. Engineers select it for seamless forged cylinder shells and heavy rings because it combines 515 MPa yield, 725 MPa tensile and 20 % elongation at about 217 HB (20 HRC) with reasonable machinability (55/100). Service temperature is limited to roughly 400 °C, weldability is moderate (45/100) and pressure-boundary welds are normally designed out; wet H2S service requires hardness held at or below 22 HRC. A372 Gr E 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 Gr E has a yield strength of 515 MPa (74.7 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 66% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
What is A372 Gr E used for?
- High-pressure gas cylinders
- Forged pressure vessel rings
- Compressor components
A372 Gr E properties
Typical room-temperature values for A372 Gr E-CL70-QT; bars are the position among steel grades.
Physical3
A372 Gr E 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 Gr E has a yield strength of 515 MPa (74.7 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 66% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
A372 Gr E is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
A372 Gr E conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of A372 Gr E takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability7
A372 Gr E's machinability is good (55/100, better than 62% of steel grades); weldability fair (45/100); formability poor (30/100).
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 Gr E is highlighted; hover a dot for its name, or open the interactive family chart.
Working with A372 Gr E
Is A372 Gr E easy to machine?
Bore and turn in the annealed or as-Q&T condition with carbide tooling, ~120–180 m/min, rigid setups; finish machine after heat treatment to hold cylinder wall tolerance.
Can A372 Gr E be welded?
Weldable with low-hydrogen E80xx-B2/ER80S-D2 consumables, 200–300 °C preheat and 620–680 °C PWHT; pressure-boundary welds on cylinders are generally avoided by design.
Can A372 Gr E be formed, bent or molded?
Hot forged/pierced at 1050–1200 °C then liquid quenched and tempered; cold forming is impractical at these strength levels.
A372 Gr E 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 |
|---|---|---|
| CCr-Mo grade, 4130/4135-type carbon level | 0.28 – 0.35 | 0.32 |
| Mn | 0.75 – 1.05 | 0.9 |
| Si | 0.15 – 0.35 | 0.25 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Cr | 0.8 – 1.15 | 0.95 |
| Mo | 0.15 – 0.25 | 0.2 |
| Febalance; verify exact ranges against current ASTM A372 edition | balance |
What surface finishes work on A372 Gr E?
Shot blast, then phosphate + paint, zinc or electroless-Ni plating; avoid hydrogen-charging plating without bake-out, and keep hardness ≤22 HRC for wet H2S service.
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
Equivalent designations
Standards and trade names that resolve to Steel A372 Gr E in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- ASTM
- A372 Grade E
How much does A372 Gr E cost?
A372 Gr E 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 Gr E — frequently asked
What is A372 Gr E used for?
A372 Gr E is typically used for high-pressure gas cylinders, forged pressure vessel rings and compressor components. In short: high-strength forged pressure steel; Q&T in three strength classes; better machining than P91/P92.
What is the yield strength of A372 Gr E?
A372 Gr E has a typical yield strength of 515 MPa (74.7 ksi) and a tensile strength of 725 MPa (105 ksi) — stronger than 66% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is A372 Gr E easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Bore and turn in the annealed or as-Q&T condition with carbide tooling, ~120–180 m/min, rigid setups; finish machine after heat treatment to hold cylinder wall tolerance.
Can A372 Gr E be welded?
With care — weldability is rated fair (45/100). Weldable with low-hydrogen E80xx-B2/ER80S-D2 consumables, 200–300 °C preheat and 620–680 °C PWHT; pressure-boundary welds on cylinders are generally avoided by design.
What surface finishes work on A372 Gr E?
Shot blast, then phosphate + paint, zinc or electroless-Ni plating; avoid hydrogen-charging plating without bake-out, and keep hardness ≤22 HRC for wet H2S service.
Can A372 Gr E be formed, bent or molded?
Hot forged/pierced at 1050–1200 °C then liquid quenched and tempered; cold forming is impractical at these strength levels.
What is the maximum service temperature of A372 Gr E?
A372 Gr E 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 Gr E CL70-QT and A372 Gr E-A?
CL70-QT is the default condition — most commonly ordered class — highest strength of Grade E for thin-wall, high-pressure gas cylinders and accumulators. A: soft intermediate condition supplied for rough boring/machining before final quench and temper — not a certified A372 delivery class. Yield strength is 515 MPa in CL70-QT versus 370 MPa in A.
How much does A372 Gr E cost?
A372 Gr E 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 Standard Specification for Carbon and Alloy Steel Forgings for Thin-Walled Pressure Vessels — ASTM International (2021)
- ASTM A370 Standard Test Methods and Definitions for Mechanical Testing of Steel Products (hardness conversions) — ASTM International (2022)
- 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)
- Machinery's Handbook (machinability ratings) — Industrial Press (2020)
- ANSI/NACE MR0175 / ISO 15156 — Materials for H2S-containing environments — NACE/ISO (2015)
- 35CrMo/42CrMo — Mysteel / 1688 (2026)
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.