ASTM A516 Grade 65
Killed, fine-grain carbon steel plate for welded pressure vessels · 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 SA-516/SA-516M — related ASME BPVC material specification when ASME Code certification is required
ASTM A516 Grade 65 is an intermediate-strength carbon-manganese pressure-vessel plate intended primarily for welded vessels where better notch-toughness behavior than ordinary structural-quality plate is important. Its defining requirements are a 450–585 MPa tensile range, 240 MPa minimum yield strength, thickness-dependent carbon limits, killed fine-grain steelmaking, and condition rules that make normalization mandatory above 40 mm. Impact performance, ultrasonic examination, simulated post-weld heat treatment and many other service-critical controls are not automatic; they must be invoked through the purchase specification, applicable construction code or project requirements.
- 450–585 MPa [65–85 ksi]Specified tensile strength · Grade 65 and Grade 450 are the customary- and SI-unit designations under the same dual standard.
- 240 MPa [35 ksi]Minimum yield strength · Determined by the 0.2% offset or 0.5% extension-under-load method.
- Over 40 mm [1.50 in.]Mandatory normalization threshold · Thinner plate is normally supplied as rolled unless another condition is ordered; normalization is normally required when notch-toughness testing is specified.
- Killed, fine austenitic grain sizeSteelmaking quality · Required through ASTM A516/A516M and ASTM A20/A20M.
- Not mandatory in the base gradeImpact testing · Charpy requirements must come from a supplementary requirement, construction code or project specification.
- ASTM A516/A516M-25Current ASTM edition · Approved March 1, 2025; verify the contractually invoked edition before ordering or accepting material.
Overview
- Designation system
- ASTM grade designation; Grade 65 is the inch-pound designation and Grade 450 is the SI designation
- Product forms
- Hot-rolled pressure-vessel-quality plate, Finished plate cut from coil, subject to the additional controls of ASTM A20/A20M
- Condition
- As-rolled for plates 40 mm [1.50 in.] and under, unless otherwise ordered, Normalized, Stress relieved, Normalized and stress relieved, Accelerated cooled and tempered, only with purchaser approval and the specified tempering treatment
- Density
- 7850 kg/m³ (Representative density for carbon steel; ASTM A516/A516M does not specify density.)
What the designation covers
A516/A516M is a plate product specification, not a general composition designation. Grade 65 applies to pressure-vessel-quality carbon steel plate produced and tested under A516/A516M together with the common requirements of A20/A20M. It does not by itself cover pipe, tube, forgings, castings, heads made under another material specification, or finished pressure equipment.
The grade number identifies its specified tensile-strength level. “Grade 65” belongs to the inch-pound system; “Grade 450” belongs to the SI system. ASTM requires one unit system to be used independently because the customary and SI values are not treated as exact conversions for conformity purposes.
The phrase “moderate- and lower-temperature service” describes the intended material category. It does not establish a universal minimum design metal temperature, maximum design temperature, allowable stress or required Charpy energy. Those depend on the governing construction code, thickness, heat treatment, joint details, service and project specification.
Specified composition
| Element or thickness range | Heat analysis, mass % | Product analysis, mass % |
|---|---|---|
| C, 12.5 mm [1/2 in.] and under | 0.24 max | 0.24 max |
| C, over 12.5 through 50 mm [over 1/2 through 2 in.] | 0.26 max | 0.26 max |
| C, over 50 through 100 mm [over 2 through 4 in.] | 0.28 max | 0.28 max |
| C, over 100 through 200 mm [over 4 through 8 in.] | 0.29 max | 0.29 max |
| C, over 200 mm [over 8 in.] | 0.29 max | 0.29 max |
| Mn, all thicknesses | 0.85–1.20 | 0.79–1.30 |
| P, all thicknesses | 0.025 max | 0.025 max |
| S, all thicknesses | 0.025 max | 0.025 max |
| Si, all thicknesses | 0.15–0.40 | 0.13–0.45 |
For each 0.01 percentage-point reduction below the applicable maximum carbon content, manganese may be increased by 0.06 percentage point above its stated maximum, up to 1.50% by heat analysis and 1.60% by product analysis.
The increasing carbon limit with thickness helps producers obtain the required strength through heavier sections, but it also means that weldability cannot be judged from the grade name alone. Actual heat chemistry, plate thickness, restraint, heat input, hydrogen control and service requirements must be considered when establishing welding and preheat controls.
ASTM A516/A516M does not impose a general maximum carbon equivalent for ordinary Grade 65 plate. If carbon-equivalent control is needed, it must be stated in the purchase requirements. Supplementary Requirement S54 contains special chemistry and carbon-equivalent provisions specifically for hydrofluoric-acid alkylation service and should not be treated as a generic Grade 65 requirement.
Mechanical requirements and their limits
| Property | ASTM Grade 65 | ASTM Grade 450 | Qualification |
|---|---|---|---|
| Tensile strength | 65–85 ksi | 450–585 MPa | Specified range |
| Yield strength, minimum | 35 ksi | 240 MPa | 0.2% offset or 0.5% extension under load |
| Elongation in 8 in. [200 mm], minimum | 19% | 19% | Subject to ASTM A20/A20M elongation adjustments |
| Elongation in 2 in. [50 mm], minimum | 23% | 23% | Subject to ASTM A20/A20M elongation adjustments |
These are specification acceptance values, not design allowable stresses and not guaranteed typical values at elevated or subzero temperature.
The strength requirements apply to test specimens representing the plate in its specified delivery condition. Actual plate properties vary with thickness, rolling practice, heat treatment and sampling location. Design values must be taken from the applicable construction code rather than inferred from the minimum yield or tensile strength.
The base specification contains no hardness requirement, through-thickness tensile requirement, fracture-toughness value, elevated-temperature tensile requirement or guaranteed reduction of area. Such characteristics should not be assumed from conformance with Grade 65 alone.
Delivery condition and toughness control
| Plate or test situation | Base specification requirement | Practical significance |
|---|---|---|
| Thickness 40 mm [1.50 in.] and under | Normally as rolled; normalization, stress relief, or both may be ordered | The purchase order must identify the required condition if as-rolled plate is unacceptable. |
| Thickness over 40 mm [1.50 in.] | Normalized | The mandatory condition must appear correctly on the material certification. |
| Notch-toughness testing required on plate 40 mm [1.50 in.] and under | Normalized unless the purchaser specifies otherwise | Impact-tested as-rolled material requires an explicit purchaser decision. |
| Accelerated cooling used to improve toughness | Purchaser approval required, followed by tempering at 595–705°C [1100–1300°F] | This is a controlled alternative, not an unrestricted mill processing option. |
| Plate produced from coil without heat treatment or with stress relief only | Additional A20/A20M testing and reporting apply | Coil-source plate must be qualified after processing into finished plate. |
Charpy V-notch impact testing is available through ASTM A20/A20M Supplementary Requirement S5, but the purchaser must define or invoke the applicable test temperature, absorbed-energy or lateral-expansion criterion, specimen orientation, specimen size and retest rules. A statement that the material is “A516 Grade 65” does not demonstrate suitability for a particular minimum design metal temperature.
For vessels receiving substantial post-weld heat treatment, Supplementary Requirement S3 permits mechanical-test coupons to be subjected to a simulated thermal cycle. This is important where long or repeated stress-relief cycles could reduce strength or alter toughness. The anticipated number, temperature and duration of cycles should be established before plate procurement.
Fabrication and service behavior
A516 Grade 65 is intended to be fusion welded using a procedure appropriate to the material, thickness and service. Welding-procedure qualification, filler-metal selection, preheat, interpass temperature, heat input and post-weld heat treatment are governed by the applicable construction code and fabrication specification. Low-hydrogen practice is generally important, particularly for thick, highly restrained or higher-carbon-equivalent plate, but the grade specification itself does not supply a universal preheat temperature.
The plate is routinely cut, rolled and formed into shells, heads and pressure components. Forming strain and thermal cycles can change strength and toughness, particularly at cold-formed regions and in thick plate. Required heat treatment after forming must be determined from the vessel construction code, forming severity, material condition and qualified fabrication procedure rather than from the A516 designation alone.
As an unalloyed carbon steel, Grade 65 has no inherent atmospheric, aqueous or process-corrosion resistance beyond that expected of ordinary carbon steel. Corrosion allowance, coating, lining, cladding, water chemistry and process compatibility are separate design decisions. Sour service, hydrogen service, wet H₂S, hydrofluoric acid and other damage-sensitive environments can require additional chemistry, hardness, cleanliness, examination and fabrication controls.
Neither lamellar-tearing resistance nor internal soundness to a specified ultrasonic acceptance class is included automatically. Highly restrained attachments, thick-wall joints or severe through-thickness loading may justify additional steel-cleanliness, through-thickness-property or ultrasonic requirements.
Examination and supplementary requirements
| Requirement | Purpose | Ordering consequence |
|---|---|---|
| S2 Product analysis | Independent check of finished-product chemistry | Must be specified; otherwise do not assume product analysis is part of the ordered testing package. |
| S3 Simulated post-weld heat treatment | Qualifies mechanical properties after a representative thermal cycle | Define the intended PWHT cycle and number of cycles. |
| S4.1 Additional tension test | Increases mechanical-property sampling | Specify when plate size, criticality or project rules justify extra tests. |
| S5 Charpy V-notch impact test | Demonstrates notch toughness at a specified condition | State acceptance criteria, temperature, orientation and specimen requirements. |
| S6 Drop-weight test | Assesses nil-ductility transition behavior for material at least 16 mm thick | Use only where required by the design basis or project specification. |
| S7 High-temperature tension test | Provides tensile data at an ordered temperature | Not a substitute for construction-code allowable stress values. |
| S8 UT to ASTM A435/A435M | Straight-beam ultrasonic examination | The examination standard and any project acceptance additions must be stated. |
| S11 UT to ASTM A577/A577M | Angle-beam examination | Typically selected for discontinuity orientations not addressed adequately by straight-beam examination. |
| S12 UT to ASTM A578/A578M | Straight-beam examination with selectable acceptance levels | State the required acceptance level and any scanning or reporting additions. |
| S17 Vacuum carbon-deoxidized steel | Permits the alternative chemistry route defined by A20/A20M | Applies only when explicitly invoked. |
| S54 HF alkylation service | Adds normalization, restricted residual elements, carbon-equivalent limits and special marking | Service-specific requirement; verify the complete S54 provisions before ordering. |
Supplementary requirements do not apply unless they are explicitly included in the purchase order or invoked by another controlling document.
Specifying and purchasing Grade 65 plate
A technically complete order should identify the governing standard and edition, Grade 65 or Grade 450 unit system, dimensions and quantity, required delivery condition, applicable construction code, impact requirements, simulated PWHT requirements, ultrasonic examination standard and acceptance level, any chemistry or carbon-equivalent restrictions, required certification, marking, surface condition and dimensional tolerances. If plate produced from coil is prohibited or requires purchaser approval, that restriction should also be stated.
| Check | Why it matters |
|---|---|
| Specification, edition and unit system | A516 Grade 65 and A516M Grade 450 must not be mixed casually in one compliance basis. |
| Plate identity, heat number and traceability | Links the delivered plate to its chemical and mechanical test results. |
| Thickness and applicable carbon limit | The permitted carbon maximum changes with thickness. |
| Delivery condition | Normalization becomes mandatory above 40 mm and may be required by toughness provisions at lower thicknesses. |
| Tensile results and specimen basis | Confirm tensile range, minimum yield and applicable elongation requirement. |
| Impact-test details | Temperature, orientation, specimen size, individual/average values and acceptance basis must match the order. |
| PWHT simulation | Confirm that the certified test coupons received the ordered thermal cycles. |
| NDE reports | Verify the ordered UT method, acceptance level, coverage and plate identity. |
| Actual chemistry or carbon equivalent | Required for welding engineering or special-service evaluation; the base standard does not impose a general CE limit. |
| ASTM versus ASME certification | ASME Code construction may require SA-516/SA-516M certification to an edition accepted by the governing Code. |
Use under ASME and substitution cautions
SA-516/SA-516M Grade 65 is the related material specification adopted in ASME BPVC Section II, Part A. ASTM A516 and ASME SA-516 are closely aligned, but ASTM-certified plate should not automatically be represented as ASME-certified plate. The material specification edition, certification wording, Code adoption tables, permitted product form, design section and project requirements must all be checked.
Grade 60 and Grade 70 are adjacent A516 strength levels, not drop-in substitutes. Grade 60 has lower specified strength and lower thickness-dependent carbon limits; Grade 70 has higher strength and generally higher permitted carbon. Substitution can affect design thickness, welding qualification, forming, toughness and allowable stresses. ASTM A515 Grade 65 is also not equivalent: it belongs to a different plate specification intended for intermediate- and higher-temperature service and does not carry the same specification framework for improved notch toughness.
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
- ASME Boiler and Pressure Vessel Code — Section II, MaterialsThe American Society of Mechanical Engineers
- ASTM A435/A435M — Standard Specification for Straight-Beam Ultrasonic Examination of Steel PlatesASTM International
- ASTM A577/A577M — Standard Specification for Ultrasonic Angle-Beam Examination of Steel PlatesASTM International
- ASTM A578/A578M — Standard Specification for Straight-Beam Ultrasonic Examination of Rolled Steel Plates for Special ApplicationsASTM International
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