SA736GrA SA-736/SA-736M-2023 | Low-Carbon Age-Hardening Nickel-Copper-Chromium-Molybdenum-Columbium (Niobium) Alloy Steel Plates

1. Scope

1.1 This specification covers low-carbon age-hardening alloy steel plates for welded pressure vessels and piping components. The specification covers nickel-copper-chromium-molybdenum-columbium (niobium) steel.

1.2 Plates under this specification are available as follows:

1.2.1 Available in Grade A, Class 3 only.

1.2.1.1 Quenched and precipitation heat treated with a minimum specified tensile strength of 85 ksi for thinner plates and 75 and 70 ksi for thicker plates, with the minimum tensile strength dependent upon the plate thickness. The maximum thickness of Grade A, Class 3 plates is limited only by the capacity of the chemical composition and heat treatment to meet the specified mechanical property requirements.

1.3 This specification is expressed in both inch-pound units and in SI units. However, unless the order specifies the applicable "M" specification designation (SI units), the material shall be furnished in inch-pound units.

1.4 The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents. Therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with this specification.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

2. Referenced Documents

2.1 ASTM Standards:

A20/A20M Specification for General Requirements for Steel Plates for Pressure Vessels
A435/A435M Specification for Straight-Beam Ultrasonic Examination of Steel Plates
A577/A577M Specification for Ultrasonic Angle-Beam Examination of Steel Plates
A578/A578M Specification for Straight-Beam Ultrasonic Examination of Rolled Steel Plates for Special Applications

3. General Requirements and Ordering Information

3.1 Material supplied to this material specification shall conform to Specification A20/A20M. These requirements outline the testing and retesting methods and procedures, permitted variations in dimensions, and mass, quality, and repair of defects, marking, loading, and ordering information.

3.2 In addition to the basic requirements of this specification, certain supplementary requirements are available when additional control, testing, or examination is required to meet end use requirements. The purchaser is referred to the listed supplementary requirements in this specification and to the detailed requirements in Specification A20/A20M.

3.3 If the requirements of this specification are in conflict with the requirements of Specification A20/A20M, the requirements of this specification shall prevail.

4. Materials and Manufacture

4.1 The steel shall be killed and shall conform to the fine austenitic grain size requirement of Specification A20/A20M.

5. Heat Treatment

5.1 The plates shall be quenched in a liquid medium from a temperature in the range from 1600 to 1700°F [870 to 930°C].

6. Chemical Requirements

6.1 The steel shall conform to the chemical composition requirements shown in Table 1.

TABLE 1 Chemical Requirements
Element	Composition, %
Element	Grade A
Carbon, max
Heat analysis	0.07
Product analysis	0.09
Manganese
Heat analysis	0.40–0.70
Product analysis	0.35–0.78
Phosphorus, max^A	0.025
Sulfur, max^A	0.025
Silicon, max
Heat analysis	0.40
Product analysis	0.45
Chromium
Heat analysis	0.60–0.90
Product analysis	0.56–0.94
Nickel
Heat analysis	0.70–1.00
Product analysis	0.67–1.03
Molybdenum
Heat analysis	0.15–0.25
Product analysis	0.12–0.28
Copper
Heat analysis	1.00–1.30
Product analysis	0.95–1.35
Columbium (Niobium),^B min
Heat analysis	0.02
Product analysis	0.01
^A Applies to both heat and product analyses. ^B Columbium and niobium are interchangeable names for the same glement and both names are acceplable in A01 specifications.

7. Mechanical Properties

7.1 Tension Test:

7.1.1 The plates, as represented by the test specimens, shall conform to the requirements given in Table 2.

TABLE 2 Tensile Requirements
Plate Thickness	Yield Strength, min	Tensile Strength
¾ in. and under [20 mm and under]	75 ksi [515 MPa]	85-105 ksi [585-725 MPa]
Over ¾ to 1 in., incl [Over 20 to 25 mm, incl]	75 ksi [515 MPa]	85-105 ksi [585-725 MPa]
Over 1 to 2 in., incl [Over 25 to 50 mm, incl]	75 ksi [515 MPa]	85-105 ksi [585-725 MPa]
Over 2 to 4 in., incl [Over 50 to 100 mm, incl]	65 ksi [450 MPa]	75-95 ksi [515-655 MPa]
Over 4 in. [Over 100 mm]	60 ksi [415 MPa]	70-90 ksi [485-620 MPa]

TABLE 2 (continued) Additional Requirements
Property	Requirement
Elongation in 2 in. [50 mm], min, %^A	18

^A See Specification A20/A20M for elongation adjustment.

7.1.2 For nominal plate thicknesses of ¾ in. [20 mm] and under, the 1½-in. [40-mm] wide rectangular test specimen may be used for the tension test, and the elongation may be determined in a 2-in. [50-mm] gage length that includes the fracture and shows the greatest elongation.

7.2 Notch-Toughness Test:

7.2.1 Charpy V-notch impact tests shall be made in accordance with Specification A20/A20M.

7.2.2 The test results of 10 by 10-mm specimens shall meet an average minimum value of 20 ft·lbf [27 J] at -50°F [-45°C].

8. Keywords

8.1 alloy steel; alloy steel plate; pressure vessel plate; low-carbon; age hardening; pressure vessels; piping components; precipitation heat treated; nickel-copper-chromium-molybdenum-columbium (niobium)

SUPPLEMENTARY REQUIREMENTS

Supplementary requirements shall not apply unless specified in the purchase order.

A list of standardized supplementary requirements for use at the option of the purchaser is included in Specification A20/A20M. Those that are considered suitable for use with this specification are listed below by title.