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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.

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]^A

42

[290]

   6

[150]

all

all

 all

all

   50 [345]^A

50

[345]

   4^B

[100]^B

all

all

all

all

   55 [380]

55

[380]

   2

 [50]

all

all

all

all

   60 [415]^A

60

[415]

   1¹/₄ ^C

 [32]^C

2

[50]

all

all

   65 [450]

65

[450]

   1¹/₄ 

 [32]

2

[50]

not available

all

^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 3¹/₂ in. [90 mm] in diameter are permitted.

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.

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^C

Plates Over 1¹/₂ in.
[40 mm] Thick and
Shapes with Flange Thickness
Over 3 in.
[75 mm]

max, %

range, %

6 [150]

all

42 [290]

0.21

1.35^D

0.04

0.05

0.40

0.15–0.40

4 [100]^E

all

50 [345]

0.23

1.35^D

0.04

0.05

0.40

0.15–0.40

2 [50]^F

all

55 [380]

0.25

1.35^D

0.04

0.05

0.40

0.15-0.40

1¹/₄ [32]^F

≤2 [50]

60 [415]

0.26

1.35^D

0.04

0.05

0.40

^G

>¹/₂ – 1¹/₄ [13–32]

>1-2 [25-50]

65 [450]

0.23

1.65 

0.04

0.05

0.40

^G

≤¹/₂ [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 ³/₈ in. [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 1¹/₂ 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 3¹/₂ 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.

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.

TABLE 3 Alloy Content

Type^A

Elements

Heat Analysis, % 

1

Columbium

0.005–0.05^B

2

Vanadium

0.01–0.15

3

Columbium
Vanadium
Columbium plus vanadium

0.005-0.05^B
0.01–0.15
0.02–0.15^C

5

Titanium
Nitrogen
Vanadium

0.006-0.04
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 Product analysis limits = 0.004 to 0.06 %.^C Product analysis limits = 0.01 to 0.16 %.

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.

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]

20

24

50 [345]

50

[345]

65

[450]

18

21

55 [380]

55

[380]

70

[485]

17

20

60 [415]

60

[415]

75

[520]

16

18

65 [450]

65

[450]

80

[550]

15

17

^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.

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.