ASTM A516 Grade 70
Killed, fine-grain carbon-manganese pressure-vessel steel plate · ASTM A516/A516M-25 — Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature Service · ASTM A20/A20M-20 — General Requirements for Steel Plates for Pressure Vessels · ASME BPVC Section II, Part A, SA-516/SA-516M — code material counterpart where invoked
ASTM A516 Grade 70 is the highest-strength grade in the A516 family of weldable, killed, fine-grain carbon-steel pressure-vessel plate. It combines a specified tensile range of 70–90 ksi [485–620 MPa] with a minimum yield strength of 38 ksi [260 MPa]. Its suitability for a particular vessel depends not only on the grade, but also on plate thickness, heat-treatment condition, impact-test requirements, construction code, design temperature, welding procedure and any service-specific controls such as carbon equivalent, ultrasonic examination or resistance to hydrogen-induced cracking.
- 70–90 ksi [485–620 MPa]Specified tensile strength · Mandatory ASTM A516/A516M Grade 70 tension-test range.
- 38 ksi [260 MPa]Minimum yield strength · Determined by the 0.2% offset or 0.5% extension-under-load method.
- Normalizing mandatory above 1.50 in. [40 mm]Heat treatment threshold · Thinner plate is normally supplied as-rolled unless another condition is ordered or required by toughness provisions.
- Killed steel; fine austenitic grain size requiredSteelmaking · These requirements distinguish A516 from less toughness-oriented pressure-vessel plate specifications.
- Not mandatory in the base gradeImpact testing · Charpy test temperature, orientation and acceptance criteria must be established by the purchase specification or applicable construction code.
- Plate onlyProduct scope · The designation does not directly specify pipe, bar, forging, casting or finished pressure-vessel components.
Overview
- Designation system
- ASTM grade designation; Grade 70 is the inch-pound designation and Grade 485 is the corresponding SI designation
- Product forms
- Hot-rolled pressure-vessel plate, Finished plate processed from coil
- Condition
- As-rolled, normally for thicknesses up to and including 1.50 in. [40 mm], Normalized, Stress relieved, Normalized and stress relieved, Accelerated cooled and tempered, subject to purchaser approval and specification requirements
- Density
- 7.85 g/cm³ (Nominal engineering value for carbon steel; density is not a specified acceptance requirement of ASTM A516/A516M.)
What the designation defines
A516/A516M covers carbon-steel plate intended primarily for welded pressure vessels where improved notch toughness is important. Grade 70 identifies the strength level; it is not a statement of allowable design stress, minimum design metal temperature, corrosion resistance, weld procedure, impact energy or finished-vessel compliance. Those matters are controlled by the applicable construction code and project specification.
| Document | Function |
|---|---|
| ASTM A516/A516M | Defines the grade-specific chemistry, steelmaking practice, heat treatment and room-temperature tensile requirements. |
| ASTM A20/A20M | Supplies common requirements for ordering, dimensions, tolerances, testing, retesting, certification, marking, quality, repair and optional supplementary controls. |
| ASME SA-516/SA-516M | ASME BPVC material specification used when the construction specification or code documentation invokes the SA designation. |
| Applicable construction code | Determines permitted materials, allowable stresses, toughness exemptions or tests, PWHT, forming, welding qualification, examination and vessel design rules. |
The material purchase order should identify the required standard edition and whether ASTM, ASME or dual certification is required.
ASTM uses separate inch-pound and SI systems. Grade 70 and Grade 485 designate the corresponding strength levels, but values from the two systems must not be mixed when determining compliance.
Manufacture and delivery condition
| Plate thickness or circumstance | ASTM A516/A516M requirement |
|---|---|
| 1.50 in. [40 mm] and under | Normally supplied as-rolled. Normalizing, stress relieving, or both may be ordered. |
| Over 1.50 in. [40 mm] | Must be normalized. |
| Notch-toughness testing required on plate 1.50 in. [40 mm] and under | Plate must be normalized unless the purchaser specifies otherwise. |
| Cooling faster than air cooling | Permitted for improved toughness only with purchaser approval, followed by tempering at 1100–1300 °F [595–705 °C]. |
Heat-treatment condition must appear on the purchase order and material certificate where it is required by design, toughness or fabrication considerations.
The steel must be killed and must satisfy the fine austenitic grain-size requirements of ASTM A20/A20M. In normal commercial production, Grade 70 develops a ferrite-pearlite microstructure, with grain refinement and microstructural uniformity influenced by rolling practice, section thickness and normalizing. Normalizing is therefore a technically significant condition, not merely a purchasing suffix.
Coil itself is not qualified as A516 plate. Coil-derived material becomes eligible only after processing into individual finished plates, including leveling, cutting, inspection, testing, any required heat treatment, marking and certification. A20/A20M imposes additional testing and reporting provisions where coil-derived plates are furnished without heat treatment or with stress relieving only.
Specified chemical composition
| Element | Plate thickness | Requirement, mass % |
|---|---|---|
| Carbon, max | 1/2 in. [12.5 mm] and under | 0.27 |
| Carbon, max | Over 1/2 to 2 in. [12.5–50 mm], inclusive | 0.28 |
| Carbon, max | Over 2 to 4 in. [50–100 mm], inclusive | 0.30 |
| Carbon, max | Over 4 to 8 in. [100–200 mm], inclusive | 0.31 |
| Carbon, max | Over 8 in. [200 mm] | 0.31 |
| Manganese | All listed thicknesses | 0.85–1.20 |
| Phosphorus, max | All thicknesses | 0.025 |
| Sulfur, max | All thicknesses | 0.025 |
| Silicon | All thicknesses | 0.15–0.40 |
Phosphorus and sulfur limits apply to both heat and product analysis. Product-analysis ranges for manganese and silicon are 0.79–1.30% and 0.13–0.45%, respectively.
For each 0.01 percentage-point reduction below the applicable maximum carbon content, manganese may exceed its specified maximum by 0.06 percentage point, up to 1.50% by heat analysis and 1.60% by product analysis.
The thickness-dependent rise in permitted carbon is important for welding and toughness assessment. Two plates can both comply with Grade 70 while having materially different carbon equivalent, hardenability and preheat needs. Procurement specifications commonly add tighter carbon, phosphorus, sulfur or residual-element limits where weldability, toughness or sour-service performance is critical; these tighter values must not be mistaken for base ASTM requirements.
Room-temperature tensile requirements
| Property | Inch-pound requirement | SI requirement |
|---|---|---|
| Tensile strength | 70–90 ksi | 485–620 MPa |
| Yield strength, minimum | 38 ksi | 260 MPa |
| Elongation in 8 in. [200 mm], minimum | 17% | 17% |
| Elongation in 2 in. [50 mm], minimum | 21% | 21% |
ASTM A20/A20M elongation adjustments apply for relevant specimen dimensions and plate thicknesses. These are acceptance requirements, not guaranteed design values at service temperature.
The grade number is based on the lower end of the tensile-strength range, not the yield strength. Grade 70 therefore does not mean 70 ksi yield. Mill certificates should be checked for both the minimum yield requirement and the upper as well as lower tensile limits, particularly after normalizing or simulated fabrication heat treatment.
Hardness, modulus, Poisson's ratio, fatigue strength, fracture toughness, elevated-temperature strength and creep properties are not acceptance properties in the base A516/A516M grade specification.
Notch toughness and low-temperature use
The phrase “moderate- and lower-temperature service” describes the intended application family, but A516 Grade 70 does not carry a universal Charpy energy or test temperature. Charpy V-notch testing is an optional supplementary requirement. If required, the purchase documents must establish the applicable test temperature, specimen orientation, specimen size, absorbed-energy or lateral-expansion criterion, number and location of tests, heat-treatment simulation and any construction-code requirements.
A vessel's permitted minimum design metal temperature cannot be assigned from “A516 Grade 70” alone. It depends on the construction-code edition, material condition, governing toughness curve or material classification, component thickness, weld details, stress ratio, PWHT, impact-test exemptions and project-specific rules. Normalized plate generally offers more consistent notch toughness than as-rolled plate, but normalizing by itself does not certify a particular low-temperature capability.
Never accept a statement such as “A516 Grade 70 is impact tested” without checking the certificate for test temperature, orientation, specimen size, individual and average results, and the represented plate or heat-treatment lot.
Welding, forming and thermal processing
A516 plate is intended to be suitable for fusion welding, but this does not remove the need for a qualified welding procedure. Preheat, interpass control, heat input, consumable hydrogen classification and PWHT must be selected from the actual plate thickness, joint restraint, heat-analysis chemistry, carbon equivalent, required toughness and applicable fabrication code. The relatively high carbon permitted in thick Grade 70 plate makes the material certificate more useful than a generic grade-based weldability statement.
Cold or hot forming changes plate thickness, local strain and potentially toughness. Forming procedures and any subsequent normalizing, stress relief or PWHT must comply with the construction code. The original plate certificate alone does not demonstrate that a heavily formed head retains all required properties after fabrication.
Where the plate will receive long, severe or repeated PWHT cycles, consider ordering tests from coupons subjected to a simulated fabrication heat treatment. ASTM A516/A516M identifies simulated PWHT of mechanical-test coupons as an available supplementary requirement. The specified simulation should represent the controlling anticipated fabrication cycle, including suitable temperature and time tolerances.
Additional examination and special service
| Requirement | Why it may be needed | Procurement point |
|---|---|---|
| Charpy V-notch testing | Low-temperature or code toughness qualification | Specify temperature, orientation, acceptance values, specimen size and heat-treatment condition. |
| Ultrasonic examination | Detection of laminations or internal discontinuities | Invoke the required method and acceptance level under ASTM A435/A435M, A577/A577M or A578/A578M as applicable. |
| Restricted carbon equivalent | Control of weld hardenability and preheat demand | State the formula, maximum value, applicable thickness and whether based on heat or product analysis. |
| Simulated PWHT testing | Verification after anticipated fabrication thermal cycles | Define the simulated cycle and required post-cycle mechanical or impact tests. |
| Product analysis | Independent verification of composition | Invoke the applicable supplementary requirement and sampling basis. |
| Additional tension testing | Greater plate- or heat-treatment-lot property coverage | Define frequency, location and represented material. |
None of these additional controls should be assumed merely because the plate is sold as pressure-vessel quality.
Base A516 Grade 70 is not automatically hydrogen-induced-cracking-resistant or qualified for wet hydrogen sulfide service. Sour-service procurement may require much lower sulfur, inclusion-shape control, calcium treatment, hardness controls and HIC testing to NACE TM0284, with acceptance ratios and test solution stated by the purchaser. HIC resistance, sulfide stress cracking resistance and general corrosion resistance are separate issues.
A516 Grade 70 is also not a creep-strength alloy or an inherently corrosion-resistant material. Elevated-temperature allowable stresses, oxidation or corrosion allowance, high-temperature hydrogen attack screening and environmental cracking controls must come from the applicable design and service documents rather than from ASTM A516/A516M.
A516/A516M includes a specialized supplementary requirement for carbon-steel plate used in hydrofluoric-acid alkylation service. It adds normalizing, carbon-equivalent and residual-element controls and specific marking. It applies only when explicitly invoked and does not make ordinary Grade 70 plate suitable for that service.
Specifying and verifying a purchase
| Item | What should be stated or verified |
|---|---|
| Designation and edition | ASTM A516/A516M-25 Grade 70 or Grade 485; invoke ASME SA-516/SA-516M and the applicable edition where code certification is required. |
| Units | Use either the inch-pound or M specification consistently. |
| Dimensions | Thickness, width, length and quantity, including permissible dimensional tolerances. |
| Manufacturing route | Discrete plate or coil-derived finished plate where route restrictions apply. |
| Heat-treatment condition | As-rolled, normalized, stress relieved, or normalized and stress relieved, with any project-specific cycle requirements. |
| Chemistry | Heat analysis, any required product analysis, residual-element reporting and contractual CE, P or S limits. |
| Mechanical tests | Required tensile coverage and any simulated-PWHT condition. |
| Impact tests | Test temperature, orientation, energy or lateral-expansion criteria, specimen size and frequency. |
| Nondestructive examination | Required UT standard, class or acceptance level; any surface examination requirements. |
| Certification and traceability | Heat and plate identity, test results, heat-treatment record, specification edition and ASTM/ASME certification status. |
| Special service | HIC testing, HF alkylation requirements, through-thickness properties, hardness limits or other project-specific controls. |
The project material specification and construction code take precedence over customary stock descriptions such as “A516-70 normalized.”
On receipt, confirm that plate markings remain traceable to the material certificate after cutting and forming. Verify that the certificate represents the ordered plate thickness and delivery condition, and distinguish actual test results from specification limits. For code construction, confirm that the certification basis and material specification are acceptable to the authorized inspection and quality-control system before fabrication begins.
Selection and substitution boundaries
Substitution cannot be based on tensile strength alone. A proposed alternative must be reviewed for product form, governing specification, chemistry, heat treatment, thickness-dependent yield strength, impact qualification, allowable stress, weldability, examination, certification and construction-code listing. An EN pressure-vessel grade such as P355GH is not a direct equivalent: its designation logic, strength requirements, elevated-temperature property framework, testing and certification differ substantially.
Likewise, A515 Grade 70 shares a nominal 70 ksi tensile-strength level but is a different pressure-vessel plate specification oriented toward intermediate- and higher-temperature service and does not carry the same fine-grain basis as A516. A516 Grades 55, 60 and 65 belong to the same specification family but have lower strength levels and different chemistry and elongation requirements.
Sources
- ASTM A516/A516M-25 — Standard Specification for Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature ServiceASTM International
- ASTM A20/A20M-20 — Standard Specification for General Requirements for Steel Plates for Pressure VesselsASTM International
- BPVC Section II, Part A — Ferrous Material SpecificationsASME
- BPVC Section II, Part D — Material PropertiesASME
- BPVC Section VIII, Division 1 — Rules for Construction of Pressure VesselsASME
- NACE TM0284 — Evaluation of Pipeline and Pressure Vessel Steels for Resistance to Hydrogen-Induced CrackingAssociation for Materials Protection and Performance
Ask MetalMate about ASTM A516 Grade 70
Discussing: ASTM A516 Grade 70
AI assistant · Responses are generated and can contain errors; verify specifications before acting.