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This specifiation covers the standard requirements for Grades 42 [290], 50 [345], 55 [380], 60 [415], and 65 [450] of high-strength low-alloy columbium-vanadium structural steel shapes, plates, sheet piling, and bars for applications in bolted, welded, and riveted structures in bridges and buildings. The alloy shall conform to the required contents of columbium, vanadium, titanium, and nitrogen. Permissible values for the product thickness and size is given. Tensile requirements (including yield point, tensile strength, and minimum elongation) and alloy content are also specified. General delivery and test report requirements are also cited.

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1.1 This specification covers five grades of high-strength low-alloy structural steel shapes, plates, sheet piling, and bars. Grades 42 [290], 50 [345], and 55 [380] are intended for riveted, bolted, or welded structures. Grades 60 [415] and 65 [450] are intended for riveted or bolted construction of bridges, or for riveted, bolted, or welded construction in other applications.

1.2 For applications, such as welded bridge construction, where notch toughness is important, notch toughness requirements are to be negotiated between the purchaser and the producer.

1.3 Specification A588/A588M shall not be substituted for Specification A572/A572M without agreement between the purchaser and the supplier.

1.4 The use of columbium, vanadium, titanium, nitrogen, or combinations thereof, within the limitations noted in Section 5, is required; the selection of type (1, 2, 3, or 5) is at the option of the producer, unless otherwise specified by the purchaser. (See Supplementary Requirement S90.)

1.5 The maximum thicknesses available in the grades and products covered by this specification are shown in Table 1.

1.6 When the steel is to be welded, a welding procedure suitable for the grade of steel and intended use or service is to be utilized. See Appendix X3 of Specification A6/A6M for information on weldability.

1.7 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 is to be used independently of the other, without combining values in any way.

1.8 The text of this specification contains notes or footnotes, or both, that provide explanatory material. Such notes and footnotes, excluding those in tables and figures, do not contain any mandatory requirements.

1.9 For structural products produced from coil and furnished without heat treatment or with stress relieving only, the additional requirements, including additional testing requirements and the reporting of additional tests, of A6/A6M apply.

TABLE 1 Maximum Product Thickness or Size

Grade
Yield Point, min
Maximum Thickness or Size
Zees and Rolled
Tees
ksi
[MPa]
Plates and Bars
Structural Shape
Flange or Leg
Thickness
Sheet Piling
in.
[mm]
in.
[mm]
42 [290]^A42[290] 6[150]allall allall 50 [345]^A50 [345] 4^B[100]^B allallallall 55 [380]55 [380] 2 [50]allallallall 60 [415]^A60 [415] 1¹/₄^C [32]^C2[50]all all 65 [450]65 [450] 1¹/₄ [32]2[50]not availableall

^A In the above tabulation, Grades 42, 50, and 60 [290, 345, and 415], are the yield point levels most closely approximating a geometric progression pattern between 36 ksi [250 MPa], min, yield point steels covered by Specification A36/A36M and 100 ksi [690 MPa], min, yield strength steels covered by Specification A514/A514M.

^B Round bars up to and including 11 in. [275 mm] in diameter are permitted.

^C Round bars up to and including 3½ in. [90 mm] in diameter are permitted.

TABLE 2 Chemical Requirements^A
(Heat Analysis)

Diameter, Thickness,
or Distance
Between Parallel
Faces, in. [mm]
Plates and Bars
Structural Shape
Flange or Leg
Thickness, in. [mm] Grade
Carbon,
max, %
Manganese,^B
max, %
Phosphorus,
max, %
Sulfur,
max,
%
Silicon Plates to 1¹/₂ in. [40 mm] Thick,
Shapes with
Flange or Leg
Thickness to 3 in.
[75 mm] inclusive,
Sheet Piling,
Bars, Zees, and
Rolled Tees^CPlates Over 1¹/₂ in.
[40 mm] Thick and
Shapes with Flange Thickness
Over 3 in.
[75 mm]
max, %
range, %
6 [150] all42 [290]0.211.35^D0.04 0.050.400.15–0.40 4 [100]^E all50 [345]0.231.35^D0.04 0.050.400.15–0.40 2 [50]^F all55 [380]0.251.35^D0.04 0.050.400.15-0.40 1¼ [32]^F≤2 [50]60 [415] 0.261.35^D0.04 0.050.40^G >½ – 1¼ [13–32]>1-2 [25-50]65 [450]0.231.65 0.040.050.40^G ≤½ [13]^H
≤ 1^H 65 [450]
0.26
1.35
0.04
0.05
0.40
^G

^A Copper when specified shall have a minimum content of 0.20 % by heat analysis (0.18 % by product analysis).

^B Manganese, minimum, by heat analysis of 0.80 % (0.75 % by product analysis) shall be required for all plates over ³/₈in. [10 mm] in thickness; a minimum of 0.50 % (0.45 % by product analysis) shall be required for plates ³/₈ in. [10 mm] and less in thickness, and for all other products. The manganese to carbon ratio shall not be less than 2 to 1.

^C Bars over 1½ in. [40 mm] in diameter, thickness, or distance between parallel faces shall be made by a killed steel practice.

^D For each reduction of 0.01 percentage point below the specified carbon maximum, an increase of 0.06 percentage point manganese above the specified maximum is permitted, up to a maximum of 1.60 %.

^E Round bars up to and including 11 in. [275 mm] in diameter are permitted.

^F Round bars up to and including 3½ in. [90 mm] in diameter are permitted.

^G The size and grade is not described in this specification.

^H An alternative chemical requirement with a maximum carbon of 0.21 % and a maximum manganese of 1.65 % is permitted, with the balance of the elements as shown in Table 2.

TABLE 3 Alloy Content

Type^AElementsHeat Analysis, %
1
Columbium^B0.005–0.05^C 2
Vanadium0.01–0.15
3 Columbium^B
Vanadium
Columbium plus vanadium0.005-0.05^C
0.01–0.15
0.02–0.15^D 5 Titanium
Nitrogen
Vanadium0.006-0.04
0.003–0.015
0.06 max

^A Alloy content shall be in accordance with Type 1, 2, 3, or 5 and the contents of the applicable elements shall be reported on the test report.

^B Columbium shall be restricted to the following thicknesses and sizes unless killed steel is furnished. Killed steel shall be confirmed by a statement of killed steel on the test report, or by a report on the presence of a sufficient quantity of a strong deoxidizing element, such as silicon at 0.10 % or higher, or aluminum at 0.015 % or higher. See table below.

^C Product analysis limits = 0.004 to 0.06 %.

^D Product analysis limits = 0.01 to 0.16 %.

Grades
Maximum Plate, Bar, Sheet
Piling, Zees, and Rolled Tee Thicknesses, in. [mm]

Maximum Structural Shape Flange or Leg Thickness,
in. [mm]
42, 50, and 55¾ 1.5 [290, 345, and 380][20][40] 60 and 65½ 1 [415 and 450][13][25]

TABLE 4 Tensile Requirements^A

Grade
Yield Point, min
Tensile Strength, min
Minimum Elonga-
tion, % ^B,C,D
ksi
[MPa]
ksi
[MPa]
in 8 in.
[200 mm]
in 2 in.
[50 mm]
42 [290]42[290]60 [415]2024 50 [345]50[345]65 [450]1821 55 [380]55[380]70 [485]1720 60 [415]60[415]75 [520]1618 65 [450]65[450]80 [550]1517

^A See specimen Orientation under the Tension Tests section of Specification A6/A6M.

^B Elongation not required to be determined for floor plate.

^C For wide flange shapes over 426 lb/ft [634 kg/m], elongation in 2 in. [50 mm] of 19 % minimum applies.

^D For plates wider than 24 in. [600 mm], the elongation requirement is reduced two percentage points for Grades 42, 50, and 55 [290, 345, and 380], and three percentage points for Grades 60 and 65 [415 and 450]. See elongation requirement adjustments in the Tension Tests section of Specification A6/A6M.